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The surface wave study of crustal and upper mantle structures of mainland China

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The surface wave study of crustal and upper mantle structures of mainland China

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Content THE SURFACE WAVE STUDY OF CRUSTAL AND UPPER MANTLE STRUCTURES OF MAINLAND CHINA by James Ping-Ya Tung A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (Geological Sciences) June 1975 UMI Number: DP28534 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI DP28534 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 UNIVERSITY OF SOUTHERN CALIFORNIA THE GRADUATE SCHOOL. UNIVERSITY PARK LOS ANGELES, CALIFORNIA 90007 G e ' y 5 T~ 2-6 T h is dissertation, w ritte n by James Ping-Ya Tung u nde r the d ire ctio n o f h i.a... D issertation C o m m ittee, and a pp ro ve d by a ll its members, has been presented to and accepted by T he G raduate School, in p a r tia l fu lfillm e n t o f requirem ents o f the degree o f D O C T O R O F P H I L O S O P H Y Dean ... DISSERTATION COMMITTEE « ^ Chairman CONTENTS Page ABSTRACT........................................ xvii INTRODUCTION .................................... 1 General statement ......................... 1 Previous geophysical studies ............... 6 Scope of the present investigation........ 18 PROCEDURE...................................... 24 Data and instrumental considerations • • • • 24 Method...................................... 31 THEORY.......................................... 34 Instantaneous amplitude ................... 34 Multiple filtering ......................... 38 Nature of the bandpass filter............. 38 THEORETICAL CALCULATIONS ....................... 52 Group velocities............................ 52 The inversion process ..................... 53 RESULTS........................................ 62 Group velocities............................ 62 Regionalization ............................ 93 General................................ 93 Calculations and test of the regionali zation ................................ 98 ii Page Application of* the regionalization • • 108 Crustal and upper mantle structures • • • • 113 General statement ..................... 113 Tibetan platform.................... 132 Southeastern China ................... 150 Northeastern China ................... 162 Central China ........................ 165 Northwestern China ................... 182 Mongolia ............. • •••••«• 191 INTERPRETATIONS ................................ 2Q6 Correlations .............................. 206 Tectonic implications ........... • • • • • 229 CONCLUSIONS....................... 239 REFERENCES....................... 242 APPENDICES............................... .. . 248 Appendix I. Derivation of the Time At tenuation by Gaussian Filter 249 Appendix II. Definitions of the duration in the time domain and fre quency domain ••••••• 254 Appendix III. Energy integrals and the partial derivatives of phase velocity.... 256 Appendix IV. Partial derivatives of group velocity and high-order group velocity. 261 Page Appendix V. Seismograms and two-dimensional plots from multiple-filter technique..................... 271 Appendix VI. Computer program lists of multiple filtering ............. 325 ILLUSTRATIONS Figure Page 1. Physiography of Mainland China •••••• 2 2. Fault distribution in China ............... 4 3* The locations of tectonic plates as sociated with China..................... 7 4. Locations of recording stations and the resulting crustal thicknesses of Tseng and Sung (1963) ................. 11 3. Dispersions given by Sung, ejt al. (1965) • l4 6. Bouguer anomaly map of C h i n a............. l6 7. Locations of earthquakes and WWNSS stations around China ............................ 19 8. Wave paths along which group velocities are obtained in the present study........... 22 9* Flow chart showing procedures in obtaining the observed group velocities ........... 27 10. Response of WWNSS long-period and high- gain instrument......................... 29 11. Comparison between the instantaneous amplitude and the real amplitude, and for different periods with different group arrivals................................ 36 12. Comparison of different values of a in the Gaussian filter on the effect of wave interference ....................... 45 13* Result of multiple filtering of NDI vertical component, September 28, 1966 . 49 v Figure Page 14. Measuring group velocities by the peak-and- trough method (period T in seconds, group velocity U in km/sec) •••••••••• 64 15. Result of multiple filtering of SHI N-S component, March 23, 1966 ............... 66 16. Result of multiple filtering of ANP vertical component, February 5, 1966 . • 68 17* Result of multiple filtering of NDI vertical component, September 28, 1966 . 71 18. The seismogram of NDI vertical component September 28, 1 9 6 6 ............ 74 19. Result of multiple filtering of LAH N-S component September 28, 1966 76 20. The seismogram of LAH N-S September 28, 1966 78 21. Result of multiple filtering of NDI N-S component September 28, 1966 •••••• 81 22. Result of multiple filtering of ANP N-S component February 7, 1966 ••••••• 83 23* The seismogram of NDI N-S component September 28, 1966 83 24. The seismogram of ANP N-S component February 7, 1966 •••••••••••• 87 25* Geologic map of China...................... 95 26. Regional division of China and Mongolia . . 99 27* Pure and composite wave—paths of south eastern China............................ 102 28. Comparison of Rayleigh wave group velocities for the low values of Tibetan platform, high values of southeastern China, and intermediate of the average from these two regions ............... 104 vi Figure Page 29* Comparison of Love wave group velocities for the low values of Tibetan platform, high values of southeastern China, and intermediate of the average from these two regions.............................. 106 30, Comparison of Love wave group velocities from calculation by regionalization technique and from composite wave path . 109 31* Comparison of Rayleigh wave group velocities from calculation by regionali zation technique and from composite wave path • • • • • • • • • • .......... 111 32. Comparison of Rayleigh wave dispersions from the China areas found by this study and average values of earth observed by others.................................. 130 33* Location and wave paths of the Tibetan platform................................ 133 3^* Resulting model of the Tibetan platform for wave path 1 in Figure 3 3 ........... 137 35* Resulting model of the Tibetan platform for wave path 2 in Figure 33 ••••*• 139 36. Resulting model of the Tibetan platform for wave path 3 in Figure 3 3 .......... l.h\ 37* Group velocities of representative wave paths of the Tibetan platform........ .. 1 hG 38. Location and wave paths of southeastern China ••••••••••••• 131 39* Rayleigh wave group velocities obtained from multiple filtering for southeastern China ••••• • •• •• ••• •• ••• 133 ^0. Love wave group velocities obtained from multiple filtering for southeastern China 157 Figure Page 41. Resulting model of southeastern China • • • 159 42. Location and wave paths of northeastern China.................................... 163 43# Rayleigh wave group velocities obtained from multiple filtering of northeastern China.................................... 166 44. Resulting model of northeastern China . . . 168 45* Location and wave paths of central China . 172 46. Rayleigh wave group velocities obtained from multiple filtering of central China 174 47* Resulting model of central China (path 3) • 1J6 48. Resulting model of central China (path l) . 178 49. Location and wave paths of northwestern China •••••••• 184 50. Rayleigh wave group velocities obtained from multiple filtering of northwestern China ••••• 186 51* Resulting model of northwestern China . . . 188 52. Location and wave paths of Mongolia • • • • 192 53* Rayleigh wave group velocities obtained from multiple filtering for Mongolia • • 194 54. Resulting model of Mongolia path 1 • • • • 197 55* Resulting model of Mongolia path 2 . . . . 199 56. Resulting model of Mongolia path 3 • • • • 201 57* Correlation between the crustal thickness and the Bouguer anomaly..................... 208 58. Relation of Moho depths of region A and the reference region ............... 211 Figure Page 59* Simplified density model for eastern China, western China and Mongolia, and the reference regions ........................... 215 60. Correlation between mobile regions and earthquakes. h: focal depth, M: mobile region, S: stable region. (Time period from 1500 to 1973, after Shi, e_t al. , 1973, Scientia Geologica Sinica, No. b) . 22b 61. Disturbance of the group velocity dis persions .................................... 227 62. Subduction of plates in the Tibetan plat form given by Chang and Zeng (1973) • • • 231 63* Distribution of subduction zones in China and Mongolia (shaded areas) ................. 235 LIST OF TABLES Table Page 1* Earthquake and recording stations used in our study • •• • •••••• •• •• .. 25 2. Values of derivatives of k with respect to w for the Gutenberg model............... 4l 3. Comparison between the results given by Tacheuchi, e_t al. (1964) and the present calculation for Gutenberg model • • • • • 54 4. Comparison between the results given by Tacheuchi, et al. (1964) and the present calculation for Gutenberg model ......... 55 5. Gutenberg model given by Tacheuchi, et al. (1964).................................. 56 6. Tibetan platform group ........... « • • • 89 7* Eastern China group ........................ 90 8* Central China group ........................ 91 9* Data used for the calculation of pure-path group velocities of northeastern China • ll4 10* Pure path group velocities of northeastern China.................................... 115 11. Pure path group velocities of northeastern China.................................... 116 12. Pure path group velocities of northeastern China.................................... 117 13. Data used for the calculation of pure-path group velocities of central China .... 118 14. Pure path group velocities of central China •• •••••••••••••••• 119 x Table Page 15# Pure path group velocities of central China • • • .................................... 120 16. Pure path group velocities of central China • ••••• ••• •• ••• •• •• 121 17# Data used for the calculation of pure-path group velocities of northwestern China • 122 18. Pure path group velocities of northeastern China •• •• ••• ••••••••••• 123 19* Pure path group velocities of Mongolia and northwestern China ••••••••••• 124 20. Data used for the calculation of pure-path group velocities of Mongolia ...... 125 21. Pure path group velocities of Mongolia • • 126 22. Pure path group velocities of Mongolia • • 127 23# Pure path group velocities of Mongolia . . 128 24. ¥ave-paths from which group velocities for Tibetan platform are obtained •••••• 135 25# Tibetan platform model fit (l) •••••• 143 26. Tibetan platform model fit (2) ...... 144 27* Tibetan platform model fit (3) ••••#. 145 28. Wave-paths from which group velocities for southeastern China are obtained ..... 154 29# Southeastern China model f i t ♦ l6l 30. Northeastern China model fit ••••••• 170 31# Central China model fit (path 3) • • • • . 180 32. Central China model fit (path l) ..... 181 33* Northwestern China model fit . ............ 190 Table Page 34. Mongolia model fit for path 1 ............. 203 33* Mongolia model fit for path 2 ............. 204 36. Mongolia model fit for path 3 ............. 205 37. Correlation between crustal thickness and Bouguer anomaly ............................. 207 38* Variations in crustal thicknesses in each region obtained from correlation of re gional Bouguer anomaly..................... 222 39. Classification of mobile and stable regions in China and Mongolia............... 226 LIST OF SYMBOLS radius of earth phase of velocity duration in the time domain duration in the frequency domain half layer thickness focal depth layer thickness wave number derivatives of wave number k with respect to frequency w path length proportional constants order number in the wave equation order number N2 = n(n+l) epicentral distance time period group velocity angular frequency i = l t 3, • • displacement i = 2, 4 stress xiii a : compressional velocity ( 3 : shear velocity p : density \ i s rigidity X . : Lame’s constant a : roll-off factor in the Gaussian filter xiv ACKNOWLEDGMENTS The author wishes to thank Dr. Ta-Lian Teng for his patient and helpful guidance and instruction during the course of this work. And he wishes to thank Drs. Thomas L. Henyey, Donald A. Palmer, and D. R. Judge for their criticisms and comments on the text. The writer is especially indebted to Dr. Richard 0. Stone for many helpful, inspiring discussions, and above all for his patient guidance on the manuscript. The author also wishes to thank Dr. Kanamori at the California Institute of Technology and Dr. Tsai at Chinese Earthquake Research Center in Taiwan for providing the computer programs to calculate the theoretical dispersions. Help from Mr. Tai-Ling Hong and Miss Linda Seekens of the Geophysical Laboratory at the University of Southern California are appreciated. In addition, the author has been benefited from discussions with Dr. Francis Wu of the State University of New York and Mr. Wei—In Chung of the California Institute of Technology. Finally, the author would like to take this chance to thank his wife, Susanna, for consistent help and en couragement during the course of this work. xv This research is supported by the Air Force Office of Scientific Research Contract Number AFOSR-7^-26o6. Com puter time was partially provided by the Computer Center, University of Southern California, xv i ABSTRACT A multiple filter technique was applied to long- period WWNSS and high-gain seismograms from earthquakes around China to extract group velocity dispersion. Seis— mograms of surface-wave paths crossing the Tibetan plat form, eastern China, western China, and Mongolia were used to obtain the local crustal and upper mantle structures* Digitized seismograms are first transformed using a fast Fourier transform algorithm. After instrumental correction, the complex spectrum is subjected to filtering in the frequency domain by a symmetrical zero-phase shift, Gaussian filter. In order to avoid severe interference between the fundamental mode and later arrivals, the parameter in the Gaussian filter must vary linearly with frequency. Group velocities in the period range of 10 to 120 seconds obtained from wave paths across the Tibetan plat form are low suggesting an unusually thick crust of ap proximately 78 km and lower shear velocities than the average continent in the upper mantle. Group velocities in southeastern China are close to those of an average continental structure with a crustal thickness of about 37 km. Group velocities of wave paths crossing all of southern China are about equivalent in values to those calculated by the path-length weighted mean of the Tibetan platform and those of southeastern China. This result shows the validity of regionalization of surface waves. By using the regionalization technique, pure-path group velocities of northeastern, northwestern, central China and Mongolia are obtained from earthquakes in Mon golia recorded at stations around the southern rim of China. The crustal thickness in northeastern China is ap proximately 30 km, and the upper mantle structure is com parable to that of southeastern China. The crustal thick ness in central China is nearly 40 km, and the low-velocity zone in the upper mantle is at a greater depth but more prominent than in northeastern China. The crustal thick ness in northwestern China is approximately 45 km, and the upper mantle structure strongly resembles that of the Tibetan platform. By correlating geotectonics, seismicity, and gravity with the resulting crustal and upper mantle structures from the present study, it was found that: 1. There are linear correlations between Bouguer anomalies and crustal thicknesses in areas of eastern China and areas of western China and Mongolia, indicating xviii a uniform crust-mantle density contrast in each of the two regions* The equal intercept thickness at the zero Bouguer anomaly, however, suggests a higher average upper mantle density in areas of eastern China than areas of western China and Mongolia* 2* Low Bouguer gravity associated with the Tibetan platform, northwestern China, and Mongolia are consistent with a model of subduction of low density crustal materials into the mantle, and 3* The wide variations of crustal and upper mantle structures in China and Mongolia can be explained by plate subductions. xix INTRODUCTION General Statement China covers one—third of the continent of Asia and an understanding of its crustal and upper mantle structure is therefore essential to any model of the tectonic history of Asia (Fig. l). Owing to the lack of suitable data, however, recent geologic and geophysical studies in the areas of China were limited to the shallow crust, and virtually no data are available about the upper mantle structures. Recent tectonic studies in China reveal the following important elements: 1. The major fault zones strike predominantly north-northeasterly in eastern China and northeast- westerly in western China (Fig. 2). Along these fault zones, crustal thickness and Bouguer gravity show abrupt changes (The Chinese Academy of Science, 197^)# 2. Based on ophiolites found in Mongolia, Zonen- shain (1973) reported that there were ancient oceans as sociated with that region. Chang and Zeng (1973) ob served that there are belts of acidic and ultrabasic intrusions and marine deposits associated with each of the 1 Figure 1. Physiography of Mainland China, o C O \ i d i L2LQ (50 m a jrT T m V P A C IF IC OCEAN fij Mountain Hill Ph y s i o g r a p h y of F i n l a n d c h i n a Scale 0 200 400 600 800 too MILK □ Basin or Plain Figure 2 Fault distribution in China (after Chinese Academy of Science, 197^0* 4 \ < mountain belts to the north of the Himalayas representing successive stages of subduction. In each case, the smaller southern plates plunged beneath the ancient Eurasian plate. 3. By studying first motions of large earthquakes in China, Molnar et al. (1973) concluded that the northward movement of the Indian plate colliding with the Eurasian plate is responsible for the majority of the earthquakes and the present tectonic activity in China (Fig. 3)• Shi et al. (1973)* hy studying seismicity and regional geologic structures in relation to plate tectonics, however, con cluded that both northward movement of the Indian plate and interactions between the Eurasian and the Pacific plates are the major controlling factors for the earth quakes and Cenozoic orogenic belts in mainland China. These studies suggest that crustal and upper mantle structures are complicated beneath the China mainland area. The purpose of this study is to make use of recent earth quake data to delineate the crustal and upper mantle structures for the important physiographic regions of the China mainland. Tectonic differences between these regions are interpreted to be the result of repeated con tinental collisions. Previous Geophysical Studies Using limited seismic refraction data from Russia, 6 Figure 3* The locations of* tectonic plates associated with China. Direction of plate motion. Plate boundaries drawn from /seismicity of the world (iJSGS, w ^ 1967; Molnar et al., 1973)• Convergent plate motion. 0’ « fsiajB t I Llpp/fi the United States Geological Survey (Terman ej; al,, 19^7) inferred the crust and mantle structure of Asia on the as sumption that the crust beneath geologically similar re gions is also similar. Results of their analysis are summarized as follows: (l) The thickness of the crust does not appear to significantly exceed 50 km except in the roots of mountains or beneath high plateaus; (2) The P- wave velocity in the upper mantle is about 8.1 to 8.3 km/sec; (3) The crustal thickness increases gradually from 20 km near the coast of eastern China to about 45 km in the continental interior except under the Himalayas and the Tibetan platform where the crustal thickness is approxi mately 70 km* Gupta and Nasrain (1967)* using both Love and Ray leigh wave dispersion data recorded at World-Wide Network of Standard Seismographic Stations (WWNSS), determined the crustal thickness of the Himalayas and the Tibetan plat form to be 65 to 70 km. Negi and Singh (1973)> using the same data but applying a ray theory technique, reported a 55 km crustal thickness with an average crustal shear velocity of 3*55 km/sec and an upper mantle shear velocity of 4.6l km/sec. The discrepancies between these two studies may be due to the limited data used, and the fact that the crustal thickness was deduced from a wave path comprised of segments which have quite different geologic characteristics. 9 Kaila et al. (1968), using P-vave refraction data from shallow earthquakes in the Himalayas, obtained the crustal structure in the foothill areas of northern India. Their results suggest three layers overlying on an 8.2-0.1 km/sec P -wave upper mantle. The three crustal layers con sist of (l) a sedimentary layer of thickness 6^1 km with a P-wave velocity of 2.7 km/sec; (2) a granitic layer of thickness 8—5 km with a P—wave velocity of 6.2-0.1 km/sec; and (3) a basaltic layer of 14-7 km with a P—wave velocity of 6.9-0.1 km/sec, giving a total crustal thickness of 28^8 1cm. Tseng and Sung (1963) selected the seismograms of two earthquakes from New Britain Islands that were re corded at 12 stations in China to evaluate phase velocit ies by applying the tripartite method first introduced by Press (1956). Locations of epicenters, recording stations, and the resulting crustal thicknesses of their study are shown in Figure h . The number in each triangle indicates the average crustal thickness within the three corner stations. Ding (1965) obtained similar crustal thicknesses by using SP waves from earthquakes in central China re corded at the same stations. The result is less reliable owing to the great uncertainty in the identification be tween the S and SP phase arrivals. Another study by Sung et al. (1965) was concerned with the thickness of the sedi— 10 Figure k Locations of recording stations and the resulting crustal thicknesses of Tseng and Sung (1963)* 11 ! 4 r t > *2 mentary layer. They made use of Rayleigh and Love group velocity dispersion in the period range h to 12 seconds from earthquakes of western China, recorded at the same stations as in the other two studies (Tseng and Sung, 1963; Ding, 1965). Figure 5 reproduces one of their dis persion curves. A Bouguer gravity map of Asia compiled by the United States Air Force (l97l) shows that anomalies in China have considerably greater variability than in other continental areas. Values range from nearly zero on the east coast of China to as low as -375 milligals on the Tibetan platform (Fig. 6). Despite the wide range of Bouguer anomaly values, variations are generally correla tive with the topography. High elevation areas have low Bouguer anomalies, and low elevation areas have relatively high values. Several features of the Bouguer gravity are noteworthy: (l) There is a Bouguer anomaly low of -575 milligals centered on the Tibetan platform with a belt of rapid decrease relative to adjacent areas from -200 to —550 milligals around its periphery; (2) Two important minima occur in the northwest part of the Tarim platform, and in western Mongolia; (3) There is a belt with high gravity gradient extending from 30°N latitude, 110°E longitude to 50°N latitude, 125°E longitude, coincident with the north-northeast mountain belt, (h) Gravity con tours are almost east-west trending in southwestern China, 13 Figure 5* Dispersions given by Sung e^t (1965). VELOCITY ro po T> r n 5 o o 00 ro c / > r n _ o o> ro o ro 4* ro T cn 2.6 (K M /S E C ) ro w 04 b o o ro I I T o o o o Figure 6. Bouguer anomaly map of China. 16 BOUGUER ANOMALY M AP OF CHINACmilligals) R EPRO DUCED FROM'BOUGUER GRAVITY ANOMALY MAP OF A S IA prepared an d c o m p ile d f r o m 1°x 1 ° m e a n B o u g u e r a n o m a lie s by t h e U S A F A e r o n a u tic a l C h a r t an d In f o r m a t io n C e n t e r —A u g . I 9 7 I turning to the north-south trending in Mongolia and eastern China, Scope of the Present Investigation Owing to a lack of adequate geophysical data that sample the deeper parts of the earth’s crust, previous studies in mainland China are limited to either surface geologic or shallow crustal structures. The dispersive nature of surface waves, having a range of appropriate periods, permits one to study the regional earth structure from the surface to successively greater depths. Further more, the dispersion of surface waves persists in areas of relatively complicated crustal structures, whereas the body—wave refraction method, for example, would encounter difficulties such as the lack of regular structural dis continuities and weak first arrivals. However, surface wave dispersion cannot be applied without adequate long—period surface wave data recorded at an adequate epicentral distance for a dispersive wave train to properly develop. Twenty-three World-Wide Network of Standard Seis- mographic Stations (WWNSS) (Fig. 7) are distributed on the rim of Mainland China. More than a hundred earthquakes of magnitude 6 or greater have been recorded since their es tablishment. All of these have epicentral distances rang ing from 2,000 to 4,500 km, thus allowing dispersion of 13 Figure 7* Locations of earthquakes and WWNSS Stations around China, WWNSS 5 fat ion long-period waves to develop. In addition, the wide distribution of earthquakes and recording stations offers numerous possibilities of wave-path combination which would allow a relatively thorough study on both the verti cal and lateral inhomogeneities. With these favorable conditions and the recently developed multiple-fliter surface wave data processing technique (Dziewonski et al., 1969)9 the scope and pro cedure of this study is to: 1. Use the multiple-fliter technique to extract dispersion information from collected WWNSS records for each path shown in Figure 8. 2. Calculate the theoretical dispersion from as sumed earth models so as to delineate the crustal and upper mantle structure corresponding to each of the observ ed dispersions, with emphasis on the shear velocity and layer thicknesses. 3# Make an interpretation of the resulting earth models with special reference to the geology and the plate tectonics of the Mainland China. 21 Figure 8. Wave paths along which group velocities are obtained in the present study. 22 V NGOLI SEA \JA P A N Nev. U 1971 Jon 2 EO Morch 7, ELLO' SEA CHINA SEA iANP OS »«* I) l»44 H O N G K O ! o hCw hkc " S O U T H C H I N A SEA BAY CH BENGA 9 0° to CO PROCEDURE Data and Instrumental Considerations The earthquakes and recording stations were selected so that the major portion of each wave path falls within the areas of China (Fig. 8). Among the potentially useful 100 earthquakes recorded at twenty-three WWNSS stations, the records of twelve large earthquakes in China and Russia were chosen for the present study. The remain ing events were not used because either the wave paths contain a large portion of undesired oceanic areas, or signals could not be recovered due to poor recordings. Locations of the selected earthquakes and stations are given in Table 1. With the exception of three recordings, the selected records generally yielded well dispersed waves. The erratic dispersion of these few cases could be attributed to the interference caused by later arrivals. Before digitizing, a zero-line is visually placed on the seismogram in such a way that (l) it is parallel to the general trend of all the traces on the seismogram, and (2) its distance from the two adjacent traces is equal to the distance between other adjacent traces. The interval of digitizing is predetermined by the epicentral 2k Table 1* Earthquake and recording stations used in our study Earthquake Latitude Longitude Magnitude Recording Station November 13, 1965 43.8°N 87.7°E 6.4o ANP February 5, 1966 26.2°N 103.1°E 6.00 ANP,LAH,NDI,SEO February 7, 1966 29.9°N 69.7°E 6.00 ANP, SEO February 13, 1966 26.1°N 103.2°E 6.20 ANP,NDI,LAH,SEO March 7* 1966 37.3°N 114.9°E 6.00 LAH,NDI,HKC March 23, 1966 23.9°N 122.9°E 6.60 LAH,SHI September 28, 1966 27.5°N 100.0°E 6.10 LAH,NDI January 18, 1967 56.7°N 120.9°E 6.00 CHG,HKC,NDI January 20, 1967 48.1°N 103.0°E 6.4o CHG,HKC,BAG August 30, 1967 31.7°N 100.3°E 6.10 LAH June 15, 1971 4l.5°N 79.3°E 5.60 CHG June 16, 1973 55.0°N 112.6°e 5.40 CHG ro Ui distance so that only the segment of the seismogram cor responding to group velocities from 4.5 km/sec to 2.0 km/ sec is digitized* The length of digitization so determined ranges from 8 minutes to 20 minutes depending on the epi central distance. Digitized seismograms are plotted to compare with the original records for possible tilting or zero-line shifting. The tilting and the shifting can be detected if the initial and final amplitudes are not zero. For the tilting, the amplitude is corrected linearly pro portional to the time. For zero—line shifting, a constant value is added to or subtracted from the amplitudes of shifted seismogram so as to make the initial and the final amplitude zero. The complete procedure is depicted in the diagram shown in Figure 9* Seismograms were taken from recording instruments with two different gain and frequency responses. 1. WWNSS long period records with pendulum periods of 15 seconds and galvanometer periods of 100 seconds. Magnification ranges from 750 to 3*000 for dif ferent stations. 2. High-gain records with pendulum periods of 30 seconds and galvanometer periods of 100 seconds. Magnifi cation ranges from 15*000 to 25*000. Responses of these instruments are shown in Figure 10. It can be seen from this figure that the peak re sponse of the WWNSS long-period instruments is about 15 26 Figure 9 Flow chart showing procedures in obtaining the observed group velocities# 27 Apply multiple-filtering Construct two dimension al plot of energy of group velocities versus periods• Calculate the epicentral distance to determine the digitization range. Convert the digitized seismogram from EBCDIC tape form to BCD tape form and IBM cards. Graphically plot the digitized seismogram to be sure that no severe errors are introduced during the digitization. Choose zero—lines of the seismogram and digitize the seismogram using Calma 303 for the segment corresponding to group velocity interval 4.5 km/sec to 2.0 km/sec. Figure 9* Flow chart showing procedures in obtaining the observed group velocities Figure 10. Response of WWNSS long-period and high-gain instrument. 800 instrumen 30 GC sec 1 00 nst ament er led □no ■ :.5 s>e 200 300 T-wave period in seconds 30 Magnification seconds, and that of the high-gain instruments is about 30 seconds. The response of* long—period instrument for periods beyond 100 seconds are apparently smaller than those periods that are shorter than 5 seconds. Neverthe less, the earth is a low-pass filter for seismic waves and, therefore, information of longer-period waves can be ex tracted from these seismograms. For the present study, the analysis was extended to a period of 120 seconds. The response of the high-gain instruments is still relatively high at periods longer than 200 seconds. A filter of 13 seconds is used in the high-gain instruments, and thus waves of periods shorter than 10 seconds are significantly attenuated (the characteristic noise level is in the period range of 1 to 3 seconds). The noise level of the long—period records is relatively higher than that of the high-gain records, but is lower than 1 percent of the maximum signals. Method Of the two surface wave dispersion methods— phase velocity dispersion and group velocity dispersion-—group velocity was chosen because it is intended to obtain the average structure over the entire path between epicenter and the recording station. Group velocities measured by the peak-and-trough method often suffer from the presence of noise and inter- 31 ference caused by the arrivals of different modes and paths of surface waves. This method also does not permit impul sive surface arrival periods to be clearly defined in the time domain. Recently, new methods of measuring group velocities have been developed (Sato, 1955; Pilant and Knopoff, 1964; Landisman, 1968, 1969; Dziewonski ert al., 1969)• The multiple filter technique has been shown to be most effective in extracting group velocity information from surface wave records of multiple modes (Dziewonski et al., 1969; Mitchall, 1973)* In this procedure, a digitized seismogram is transformed to the frequency domain. After instrument corrections, the complex spectrum is sub jected to filtering in the frequency domain by a sym metrical, zero—phase shift, Gaussian filter of the form: F(w) a Exp(- ( S ^ M 2) o in which, wq is the center frequency, w is the variable frequency, is a parameter which controls the roll-off and the width of the filtering band. It is then inversely transformed to give the amplitude spectrum in the time domain. The arrival time of the maximum amplitude cor responds to the group arrival time for the frequency wq. This same process is repeated for different center fre quencies to yield the corresponding group arrival for each of the center frequencies. This method has several advantages over the peak- 32 and-trough method: (l) the group velocity can be measured as a continuous function of* the period, i.e., the fre quency increment in the analysis can be set as small as one needs, (2) a greater period range of group velocities can be obtained, and (3) waves of different modes are separated on the two-dimensional plot obtained by applying this method. 33 THEORY Instantaneous Amplitude The fact that group velocity represents the velocity of energy transmission has been demonstrated by Lamb (19^5) and Tolstoy (1973)* It is the basis of the peak-and-trough method in measuring the group velocity and also the basis on which the definition of group velocity, U = dw/dk (Ewing et al,, 1957)> was derived when evaluating the complex inverse Fourier integral by the stationary phase approximation. The amplitude obtained from the real part of the inverse Fourier transform does not represent energy arrival; instead, it represents merely the ground displacement or ground particle velocity, depending on the response of the seismometer. In order to evaluate the group arrival from a seismograra of an actual earthquake, the energy arrival must be considered, and consequently, the amplitude from the inverse Fourier transform needs to be redefined. The (energy) spectrum of a time signal is defined as the square of the absolute value of the Fourier trans form of the signal. Thus a signal g(t) has the Fourier transform 3k 0 0 G(f) = J g(t)elwtdt (1) - CO if the integral converges. Parseval’s formula G(f) 2df = J e(t) 2dt (2) 00 states that the total energy in the frequency domain is equal to the total energy of the time domain. Prom the right-hand side of equation (2), it is noted that g(t) is the energy input per unit time, or the instantaneous power. For a real time signal, the instantaneous power is simply the square of the amplitude. However, when the in verse Fourier transform becomes complex, the imaginary part must be taken into account to obtain the equivalent in stantaneous power. If the time signal can be expressed by g(t) = x(t) + iy(t), (3) the instantaneous power is g(t)2 = (x(t))2 + (y(t))2, (4) and g(t) is defined as the instantaneous amplitude (Goodman, i960) for the measurement of the amplitude and the phase from an electronic oscillator. Physically, the instantaneous amplitude represents the envelope of the time signal (Fig. ll)• In this figure, two different periods with different arrivals of instantaneous amplitude maxima are illustrated. It can be seen that the attenua tion or the drop-off of the instantaneous amplitudes are different for different periods, depending upon the para- 35 Figure 11. Comparison between the instantaneous amplitude and the real amplitude, and for different periods with dif ferent group arrivals. 36 t. = group arrival Instantaneous Amplitude Real Amplitude T- s period t9 = group arrival Instantaneous Amplitude Real Amplitude period 37 meter a used in the Gaussian filter. From this definition, it is clear that the instan taneous amplitude reflects the energy arrival at any in stant. The amplitude maximum is, therefore, defined to be the group arrival. Multiple Filtering If we evaluate the instantaneous amplitude from the original Fourier spectrum, the total energy contribu tion from all frequencies is obtained. Xn order to separate energy from different frequencies, multiple filters are designed, with each filter centered at a particular frequency. Hence, when the inverse Fourier transform is performed on the filtered spectrum, the in stantaneous amplitude represents the instantaneous energy for a particular frequency. The maximum of the instan taneous amplitude thus represents the arrival of an energy concentration for this particular frequency. This is pre cisely the definition of group arrival. The ratio of the epicentral distance to the group travel time gives the group velocity for this particular frequency. This pro cess can be repeated for a range of frequencies, each time using a filter of different center frequency. Nature of the Bandpass Filter It was shown by Dziewonski and Hales (1972) and 38 Herrmann (1973) that local amplitude maxima do not always coincide with group arrivals but only true when wave number k is close to a linear function of the frequency w. To satisfy this condition, narrow bandpass filters are de signed (Dziewonski and Landisman, 1969; Herrmann, 1973) so that within the filter band wave number k is indeed a linear function of w or very nearly so. The filter is de fined as: w < w — Band o o /w - w_ x 2 II (w) = e w 7 x 7 o w - Band < w < w + Band (5) o o v 7 w > w + Band o This leads to the question as to how narrow the filter band width must be. To answer this, expand the wave number k in a Taylor*s series 1 • . -.// \ , " (w — w ) k = k + k (w — w ) + k ----o7 + o v o7 21 , / / / (w - w ) t r\ k v— T T ° + .... '6' where , dk 1 , / / d k , , , / / / d3k { = — k = 1— p" and k = -— 5 dw w=w dw 1 w=w dwJ w=wQ By evaluating the relative strength of k*(w - wq), q) . ■ 9 and k*' ^w ~ w q) — we will be able to see 2 I 3 ! whether k is close to a linear function of w. For the 39 j:>urpose of doing this, a group velocity dispersion is ob tained from a continental Gutenberg model, and it is fitted to a fifth order polynomal for the periods from 20 to 110 seconds, namely: U(w) = 3. 52 + 4. 03w + 54. 75w - 796. 86w + 2679. 4w^ -2738. 5w^ (7) 2 3 d k d k From this polynomal, both --^ and --^ can be obtained dw dw by the following formula: d2k d / dk d /I \ _ _L_ du ^ 2 dw \ d w ; dw yu J 2 dw A = A . '-2 3 dw . . - dw 'dw 7 \ u / u 7 u dw u For the Gutenberg model, values of selected periods are shown in Table 2. For the entire period range (20 to 110 seconds), wq = 0.157 (To = 40 sec) and w - w q can be as large as 0.157 (w = 0.314); the relative values of \ . ..(w - w )2 , . ...(w - w )^ k* (w - w ) , lc* 1 v _ 1 o7 , and k* * * v--— — o7 are ' o 2' 3 k" (w - W q )2 k’1 ’ ( w - w ^ (0. 157)2 2 0. 318.(0.0785) „ _ 6 4.053 ------------- = 0.095 / dk _ _d_ /1_\ _1_ \ dw; dw \u J ^2 /d k\ _ d / 1 du\ _ • 1 du\ _ 1 d u 1 /du\ I, 2y dw I 2 dw / 2 dw) 2 2+ 3 Idw/ 'dw 7 \ i i / n 7 n nw n \ 7 1 , . 0.264 1 0.264 — (w-w ) — (w-w ) u 0 u O = 0.063 When the filter bandwidth is taken as / , that is de- V. o/2 fine w-w - w / , it was observed that the maximum ratios o °/2 of second and third terms to the first are reduced to .047 and ,015* respectively. When the filter bandwidth is reduced to only w q/4, the ratios become even smaller, namely .024 and .00394, respectively. Therefore, it is a valid assumption that k is a linear function of w when the 40 Table 2. Values of derivatives of k with, respect to w for the Gutenberg model T.period w,frequency U=dw/dk d2k/dw2 d3k/dw3 20 0. 314 3.201 -0.139 -7.9717 30 0.209 3.497 0.473 -1.525 40 0.137 3.785 0.318 4.053 30 0.126 3.892 0.139 6.019 60 0.105 3.915 0.004 6.619 70 0.089 3.905 -0.095 6.623 80 0.079 3.882 -0.170 6.339 90 0.070 3.856 -0.225 5.915 100 0.063 3.831 -0.267 5.425 110 0.057 3.807 -0.299 4.911 4l filterband is narrower than wq , In the present study, a bandwidth of w0/2 was used, a value also utilized by Dziewonski and Landisman (1969)* The parameter a in the Gaussian filter serves as a damping factor, and also affects the bandwidth in that at the two ends of the filterband, the amplitude is re duced to exp(- i t ) , or less than that of the maximum value. This is done in order to suppress high sidelobes (Landis man et al,, 1969). From the approximation formula given in the Appendix and by Dziewonski and Hales (197^), it is shown that the damping of the amplitude in the time—domain by this filter is exp( - w 02(t - t0 )2/4. 2) (8) Since a is in the denominator, a larger value implies smaller damping for time-domain signals. Because of this property of the bandpass filter, we cannot let a become too large. According to the uncertainty principle (Papoulis, 1962), the duration of a signal in the time- domain is approximately a reciprocal of the duration in the frequency domain for a function comparable to the Gaussian function (the definitions of the duration in the time and frequency domains are given by Papoulis and are listed in Appendix II), If the duration in the frequency domain is narrow, the duration in the time domain will be very broad. For a single mode, monotonic dispersion with k2 out later arrivals, the broadness of the time pulse does not affect the position of the amplitude maximum, or group arrivals. On most seisinograms of actual earthquakes, how ever, both higher-mode waves and later arrivals are pre sent. Those arrivals will give several amplitude maxima in the time-domain. The broadness of each of these maxima depends on the frequency, the damping effect of the earth and the damping factor . in the Gaussian filter. If the duration of each of these maxima is long, and their rela tive arrival times are close to each other, interference could occur (Dziewonski and Landisman, 1969; Herrmann, 1973)* in fact, Herrmann (1973) observed that in order for two signals not to severely interfere with each other, the arrival time difference t^ of the two signals should satis fy the conditions (9) which is derived from the condition (10) That is, at a time ~-d away from the arrival of the signal, we require that the amplitude reduces to exp(- ) of the maximum amplitude for the waves with frequency wq. From 9t can be put in the following form: (11) 43 which, states that if* the two modes arrive at t^ time apart, a should be equal to or less than the value given by (ll) to avoid severe interference. Notice also that in (ll) the choi e of a is frequency dependent. In Figure 12 a time function of two single pulses of period h seconds, arriving 5 seconds apart, is Fourier transformed and filtered by the Gaussian filter, with different values of a as indicated in Figure 12, Using formula (ll), a is _ 52 tt < . ^ ( i 2 . ' I a — 77 - 1. 2 ' ' 4. 42 In fact, even is slightly larger, for example a = 2 in Figure 12; the interference is already not significant. If we put -,693 ( = ln(0,5)) instead of - iron the right- hand side of (lO), that is, if the two pulses have their half maximum value added together at middle point between them, the amplitude is likely to exceed the original maxima, and a new amplitude maximum between them will be formed. For this case, the corresponding cyis: 2 2 2 2 V td _______ _ TT . 5______ _ , a 4 To^(0. 693) 4. 42(0. 693) It is seen in Figure 12 that when a is 6 or greater,the original two time pulses gradually become one. From these analyses, we conclude that the choice of a cannot be random but depends on the relative arrival times of different modes, later arrivals and also on fre quency w , kh Figure 12. Comparison of different values of ol in the Gaussian filter on the effect of wave interference. ^5 150.oo: lo -O - « _o o o o o Csi CO <1> J C \ J ....... . V. « P o ■-* " I I I I f 1 II t T T r 1 t I I I I I I I I I I I L I I I ■ I ; j ? , x ? * _ • • - r \ # • i V>'" rrrrr iTi i i i i i iTrrri r i i i in rr^rrrT o o o * o ° - o , \V o . - \ TTTTTn ! t t i i i rr i j r i t t r n i i ; r \ « * L“^- v,-o^>-f^cJ'V^ \ * 2 5» ^ * - ' - tWf » Ci)d : = > 46 .00 4.0C 8. 00 12. 00 18. 00 20. 0.00 4. 00 8- 00 12. 00 16. 00 20 FCT) ft o CD --- r FCT) F C T ) FCT) n n "r.nt Figure 13 illustrates a typical two-dimensional output (a detailed explanation of this output will be given in the chapter on Results). In the short period range (periods less than 20 seconds), there are usually higher modes having group velocities from 3*5 km/sec to 4.1 km/ sec. In the long period range (periods greater than 45 seconds), a considerable amount of energy (indicated by amplitude maxima) arrives with group velocities from 2.5 km/sec to 2.9 km/sec. The latter could come from later refractions, or from the slow attenuation of long period waves. The fundamental mode has a group velocity of ap proximately 2.8 km/sec at a period of 20 seconds, and 3*6 to 4.0 km/sec at the longer periods. The epicentral dis tance was 2529 km. With these data, the relative arrival times for different modes can be calculated. 1. At the short period range (take a 15 second period) 225r^ ( 1 7 ) , - ,2^l9(k/ m) ' = 903(sec) - 684 (sec) = 219 sec (l*0 2. 8(km/sec) 3.7(km/sec) using Tq = 15 sec, t^ = 219 sec, the cor responding upper limit of a from (ll) is 167* 2. At longer period range (period 60 seconds) 2529(km) 2529(km) = 972(gec) _ 665(sec) = 308 sec (15) 2. 6(km/sec) 3. 8(km/sec) and the corresponding CC is 21. These calculations indi cate that, in order to avoid severe interference, the 48 Figure 13* Result of* multiple filtering of NDI vertical component, September 28, 1966. 49 GROUP VELOCITY ( k m / s e c ) PERIOD (second) 11* 12. 13. IS . 18 . 2 2 . 25. 2 8 . 3 3 . 3 9 . 42. 4 6 . 5 0 . 5 5 . 62 . 6 6 . 71 . 76 . 8 2 . 8 9 . <38.108.1 20. NDI vertical component Septem ber 28 1966 4.0 0 3 4 0 3.5 0 4 3.5 2.5 3 • 8. 9. 9. 10. 1 I • 12. 13. 14. 15. 17. 10. 20 • 2: 2 2 . 21 • 21 • 20 • 19. 50 value of should be frequency-dependent* In fact, accord ing to (ll), a should be proportional to the square of frequency* However, if we put this value into (8), the frequency square factor in the nominator is cancelled, and the damping effect in the time domain becomes constant over all frequencies* For this reason, a was chosen as a linear function of frequency in this study. a = m • u ) (l6) Since the relative arrival times depend on the epicentral distance, the constant m in (16) is made pro portional to epicentral distance A . Therefore, a = m' • A • u) (17) In this study, the constant m' in (17) ranged from 0*06 to 0.12 depending on the relative arrival times. 51 THEORETICAL CALCULATIONS Group Velocities The classical calculation of the group velocity U is based on a direct differentiation of phase velocity c with respect to the wave number k, U = dw/dk = c + kdc/dk where the phase velocity is obtained from solving the Ray leigh equation for a layered half space, or calculated through Jean's formula from free oscillation periods for a spherical earth. The phase velocity is not exact be cause of extended numerical calculations, and thus the group velocity could be grossly in error when calculated with an additional numerical differentiation. An alternative method to calculate the group velocity which circumvents the above difficulty is by way of a variational formulation first introduced by Takeuchi and Saito (1962). In this variational method, the funda mental differential equations are transformed into a set of energy integrals with boundary conditions incorporated. Therefore, instead of a numerical differentiation, the new method generates the group velocity through a numerical integration, which has the obvious advantage of reducing 52 the calculation errors. There are altogether eight energy integrals, I to Ig defined by Takeuchi and Saito (1962), and they are given in the Appendix XII. From these integrals group velocities are calculated by the formula: U = i/cl L 3 1 for Love waves (I -21 ) + 2N2(I +21 ) - (aa)2I„ _ Cdi + N X2 The calculated group velocities in the present computer program were tested using the Gutenberg model by the results given by Tacheuchi, Dorman, and Saito (1964). The differences are less than 0.02 km/sec for the Rayleigh waves, and 0.001 km/sec for the Love waves (see Tables 3 and 4). For a twenty-point dispersion curve, the computa tion time on an IBM 370 is approximately one minute for Rayleigh waves and thirty seconds for Love waves. The Inversion Process In the absence of crustal and mantle velocity in formation for Mainland China, we began our inversion pro cess from the continental Gutenberg model (Table 5)• In the present data, observed group velocities were extended to a period of 120 seconds, which corresponds to an effective sampling depth of about 400 km (one wave length). According to previous results (Saito, 1967)* the 53 Table 3. Comparison between the results given by Tacheuchi e_t al. (196k) and the present calculation for Gutenberg Model Love Wave Values n given by Tacheuchi e_t al. T.sec C,km/sec U.km/sec The present T. sec calculation C.km/sec U.km/sec 100 88.23 4.514 4.237 88.247 4.5136 4.2369 120 74.4o 4.465 4.207 74.396 4.4653 4.2072 150 60.34 4.408 4.147 60.339 4.4081 4.1468 210 46.15 4.327 4.008 46.146 4.3265 4.0081 250 37.63 4.247 3.850 37.625 4.2472 3.8507 300 20.33 3.933 3.508 20.332 3.9337 3.5082 • p - Table 4, Comparison between the results given by Tacheuchi et al. (1964) and the present calculation for Gutenberg Model Rayleigh Wave Values n given by Tacheuchi at al, T.sec C.km/sec U.kni/sec The present Tf sec calculation C ,1cm/ sec U,km/sec 100 97.02 4.106 3.836 96.995 4.1065 3.8334 120 81.73 4.065 3.880 81.353 4.0676 3.8652 150 65.97 4.032 3.912 65.977 4.0314 3.9087 200 49.90 4.001 3.891 49.892 4.0017 3.8927 250 40.25 3.970 3.791 40.219 3.9733 3.8161 500 21.70 3.686 3.100 21.789 3.6707 3.1846 Ui Table 5. Gutenberg model given by Tacheuchi et aJL. (1964) Depth., km _________ p g/cm__________ a 3cm/sec_________( 3 km/sec 0- 19 2* 74 6.14 3.55 19- 38 3.00 6. 58 3.80 38- 50 3.32 8.20 4.65 50- 60 3.34 8.17 4.62 60- 70 3.35 8.14 4.57 70- 80 3.3 6 8.10 4.51 80- 90 3.37 8.07 4.46 90- 100 3.38 8.02 4.4l lOO- 125 3.39 7.93 4.37 125- 150 3.41 7.85 4.35 150- 175 3.43 7.89 4.36 175- 200 3.46 7.98 4.38 200- 225 3.48 8.10 4.42 225- 2 50 3.50 8.21 4.46 250- 300 3.53 8.38 4.54 300- 350 3.58 8.62 4.68 350- 4oo 3.62 8.87 4.85 4oo- 450 3.69 9.15 5.04 450- 500 3.82 9.45 5.21 500- 600 4*01 9.88 5.45 600- 700 4*21 10.30 5.76 700- 800 4.40 10.71 6.03 800- 900 4*56 11.10 6.23 900-1000 4.63 11.35 6.32 56 proper starting depth, of integration is about twice the horizontal wavelength. Hence, for a period of 120 seconds, the starting depth of integration should be about 800 1cm, The Gutenberg model consists of 2k layers within this depth. In our fitting process, however, the number of layers varies from 2k to 26 to fit the variations of the group velocity. Realizing that the perturbation of the surface wave dispersion curve depends in a large measure on the changes of shear wave velocity (less so on the changes of compressional wave velocity and rather insensitive on the changes of density), the inversion process was started by seeking a shear wave model to satisfy the Love wave dis persion data. This was accomplished by holding the density structure unchanged while successively modifying the shear wave velocities at various depths. Since group velocities are most sensitive to the structure at a depth corresponding to one-third of their wavelength, the fitting procedure was proceeded from short—period to long- period end, or from shallow to deeper structure. In order to make the group velocity inversion pro cess more effective, partial derivatives of the group velocity with respect to layer parameters were derived in terms of the energy integrals and partial derivatives of the phase velocity with respect to layer parameters. The 57 partial derivatives of the phase velocity were derived by Takeuchi e_t al. (1964). These partial derivatives are listed in Appendices XXI and IV. However, because of the unstable numerical results of the partial derivatives of group velocities, they were not used in the fitting pro cess. Discussions on the numerical values of the partial derivatives and the numerical instabilities are included in Appendix IV. Due to the failure of applying the method of par tial derivatives of group velocities, the fitting process was accomplished essentially by using trial-and—error techniques, nevertheless, the layer parameters were ad justed with the following criteria in mind: 1. The period range in which group velocities in crease rapidly, or the range of steeper slope of group velocity represents the transition from crust to the mantle. Therefore, this criterion was used to determine the thickness of the crust. For example, if the steeper slope ranges from periods of 2 5 to 40 seconds, the cor responding crustal thickness is likely around 30 km. 2. The slopes of group velocity curves for periods longer than 50 seconds reflect the depths and prominence of the low—velocity zone in the upper mantle. A steep negative slope (group velocity decreases with periods) indicates a prominent low—velocity zone (shear 58 velocity reduces 0*25 km/sec or more) at a relatively shallower depth. 3. The slope of the group velocity curve in the short periods (less than 25 seconds) reflects the pre sence and thickness of low—velocity sediments at the earth*s surface. The densities in each model were held unchanged during the fitting process, but they were adjusted to meet the observed Bouguer gravity anomalies (Fig. 6), using an iterative procedure to modify the densities in the top 100 lcm. Before we go into the detailed procedure of fitting, let us digress for a moment to remark on the connection between the density and the Bouguer gravity anomaly. Ac cording to the definition of the Bouguer Anomaly: B.A. = (G - + Ch + ) - theore- v obs topo free air B7 tical. where Gobs : observed gravity value Ctopo: topographic correction . : free air correction free air C . , . , : Bouguer correction J d All the gravity corrections in the parentheses are for the reduction of the observed values to a datum surface as if they were measured there without mass above the datum. Thus, we may call the value obtained from the parentheses, 59 the adjusted observation value. ¥hen the theoretical value is subtracted from this value, the difference indicates the anomalous gravity at the point of observation below the datum as compared with the theoretical value. The anomaly must have been contributed from anomalous density distribu tion below the datum. Let us assume that the theoretical value was calculated from a particular set of densities (by assuming infinite flat layers): Theoretical = ^ G P. H. i 1 1 where P_^ : the density of the i*'*1 layer t h KL : the thickness of the i layer G: the mass-gravity conversion constant. If the isostatic compensation is achieved around a depth of 100 km (Woollard, 1972), then the anomaly must come from the density difference above this depth. Therefore, the fitting is to adjust the densities above 100 km so that the gravity deficiency produced would be equal to the observed Bouguer anomaly. In the calculation, a zero Bouguer anomaly (the theoretical value) was assumed for a typical oceanic model (last model in Fig. 3 of Press, 1970)• During each iteration, a density increment was add ed to or subtracted from each layer, and the gravity was calculated for the top 100 km. Then this value was to com pare with the gravity from the oceanic model for the same depth. When the difference between the two calculated gravities was within 10 milligals of the observed Bouguer anomaly (Fig. 6), the fitting was considered achieved. Final fitting was considered accomplished when the differences between the observed and the calculated group velocities were less than 0.05 km/sec in the period range of 20 to 100 seconds. For periods shorter than 20 seconds and longer than 100 seconds, because either larger errors are in the theoretical calculations or the observed values are less reliable, the calculated group velocities are fitted only as close as 0.2 km/sec. Once the shear velocities have been determined by the Love wave dispersion data, compressional velocities are varied in the model to fit the Rayleigh wave dis persion in the same way as outlined above. For those wave-paths along which there is no Love wave dispersion available, the fitting was accomplished by varying both compressional velocities and shear velocities such that Poisson’s ratio of one-fourth holds. 61 RESULTS Group Velocities Observed group velocities were obtained from both interpretation of the two-dimensional plots of multiple filtering and application of the peak-and-trough method. Results of multiple filtering of each of the seisraograms selected are shown in Appendix V. These plots differ from Dziewonski*s (1969) in that the amplitudes are normalized with respect to the maximum value at each frequency, rather than the maximum value for the entire spectrum. Therefore, the energy distribution reflects seismograms with equal amplitude over all the frequencies. The ad vantage is to amplify the low energy, long-period waves so that the dispersion can be observed more easily. The dis advantage is that it is easy to interpret low-energy noise as signals, especially in the longer-period ranges. How ever, the disadvantage always can be overcome by examining the original amplitude spectrum. In the two-dimensional plots, group velocities were selected in the following manner: 1. All the amplitude maxima were considered pos sible group arrivals. The peak—and— trough method was used 62 to obtain a set of group velocities independently whenever possible (Fig. 14). Amplitude maxima were accepted as group arrivals if their values were within reasonable agree ment with the values measured from the peak-and-trough method. In Figure 15» group velocities obtained by the peak-and-trough method from the seismogram in Figure 14 are marked by crosses. It can be seen that group velocities obtained by taking amplitude maxima from the two-dimension al plot and from the peak-and-trough method are in good agreement. Differences are less than 0.02 km/sec, the increment of group velocity in the plot. The peak-and- trough method can be applied only to measure a few group velocities when each of the peaks and troughs on the seismograms is well-defined, such as shown in Figure 14. By applying the multiple filter technique, not only the group velocity can be measured as a continuous function of the period (the peak-and-trough method can give only group velocities of discrete periods), but also a greater period range of group velocities can be obtained. 2. For those periods where no corresponding values can be measured by the peak-and-trough method, amplitude maxima which can be connected smoothly with those group arrivals found in 1 are taken as group ar rivals. 3. When there are no amplitude maxima available to make smooth connections for some periods (Fig. 16), 63 Figure l4# Measuring group velocities by the peak-and-trough method (period T in seconds, group velocity U in km/sec)* T = 50 U = 3.550 T U 73 3.775 T = 28 U = 3.284 T=4l U=3.4(1)9 T = 53 U = 3.66fr T=39 IT=3.338 T = 44 U = 3.472 T = 24 U = 3.156 1 65 Figure 15* Result of* multiple filtering of SHX N—S component, March 23* 1966. 66 GROUP VELOCITY Ikm/sec) PERIOD (second) 13* 15. IU . 22 . 2 ” 3 3 . 39. 4 2 . «e. *0 . 55 . 6 2 . 6 6 . 7 1 . 7C. 02. 69. 9 6 .1 0 8 .1 2 0 . 120 4 .050 4. 026 4 .0 0 3 3 .9 8 0 3 . 9 57 3.9 35 3 . 9 12 3 . 890 3 .0 6 9 3 • 847 3 .6 2 6 3 .6 0 5 3 • 784 3 .7 6 3 3 . 743 3. 723 3 .6 9 9 3 . 675 3 .652 3 .6 2 9 3. 606 3 . 584 3 .5 6 2 3 .5 4 0 3 . 5 19 3 .4 97 3. 476 3 .4 5 5 3. 435 3 .4 14 3. 394 2. 982 2. 89 7 2 .4 3 6 r l i fe • 99. 0 24 7 1 . 100. 99 . 96 . 00*- 0 0 . 99. 9 0 . 96 . 80*. 70 . M * <J7. 95 • 9 7,,■ — 8 0 . 6 2 * 9 J . 90*. flp*' 6 L*-■^52 . 57. 49. ^73 . 4 3. 5 1 . 4 3. 82- “ T t . 67. /4 2 . 34. 45 . 1 7. "/S. 7 2 . 70 . 6LV 34, 25 . 40 • 32 . 67 . 64 . ft 3*.^ < 6 . 2 8 . 1 9 . 36 , 2H . 577 “ t t : 5 1 • 25 . 1 4. 12 . 24 . 51 . 4 9. 5 1 . 47. 24 . 1 3. 3 0 . 2 2 . 44. 42 • 45 . 43. 24 . 14. 2 7. 2 0 . 36. 35 . 40 . 40 • 25 . 1 6. 2 6 . 19. 29. 20 . 34 . 36. 26 . 1 8. 24 , 1 P. 2 2 . 2 2 . 30. 33. 27. 20. 2 3 . 1 9. 17. 17. 2 5 . 30. 2 6 . 20. 22 . 19 . 12. 1 2. 22. 27. 25 . 20 . 2 1 . 20. e . P. 1 P. 2 1. 23 . 19. 1 9 . 21 • 6 • 6 • 15. 20 • 2 1 • 1 8. 1 S. 2 2 . 6 . 6 . 1 3. 17. 1 8. 15. 16 , 23 . 7. 6. 1 1 • 13. 16. 1 3. 14. 24 . 6 • 7 • 1 0. 10. 1 4 . 19. 1 2. 24 . 9 . 8 • 9 . 1 2 . «, 1 1 • 2 S . 10. 9. 8 • 5. 1 1 • 7, 1 1 • 2 6 . 10. 9. 0 . 1 0. 9. 1 3. 2 7 . 1 0. I 0. 8. 2 . 1 1 • 12. 1 8 . 2 3 . 10. 10 . 9 • 4 • 12. 15. 1 9. 29 • 10. 1 0 • 9. 7. 1 4 . 1 9 . 22 • 10. 1C. 11 • 1 C. 10. l r. 23 . 2 6 . 31 • 11 • 1 1 • 13. 20 . 27. 2 9 , 3 2 . 9. 1 0. 1 2 . 16 • 24 . 3 1 • 31 . 1 3 • 0. 10. 1 3. 1 8. 26. 33. 3 3 . 31 . 7 . 9 . 1 3 • 19. 2 9. 36. 34 . 32. 6. 0 « 1 2. 2 0. 30 . 37. 34 . 3 1 . 5. 7 . 1 1 . 20 • 3 1 . 37. 3 3 . JO, 4 . 6 • 10 . 19. 3 1 • 37 . J1 • 27 . 3. 4 • 9 • 10. 31 . 3 5 . 2 0 . 24 • 2 • 3. 8 • 17. 29 . 33. 24 • 21 • 1 • 2 • 6 . 1 5 . 2 3. 11 • 1 9 • 1 7 • 1 . 1 • 1 3. 26. 2 9 . 18. 1 1, 1 • 1 • 4. 12. 28. 27 . 12. 1 0 . 2. i • 3 . t 1 • 24 . 26 . 1 1 • 9 . 2 . i • 2. 1 0 • 23 . 26. 1 2. 1 0. 2. l • 2 . 1 0 • 22 • 2 5 . 1 5. 12. 3. 3 • I 0. 22 • 2 8 . 1 7. 15 . 3. 3. 4. 11 • 2 1 . 24 . 1 M. 1 7. 4 , 4 . 6. 12. 21 . 2 J . 1 P. 1 0 . 4 • 5. 7. 1 2 . 20 . 2 1 • 1 7 . 1 9 . 4 . 8 . 12. 1 P • IS . 1 8. 1 9. 5. 6. 3. 12 • 16 . 15. 1 1 • 1 9 . 4 . 6 . 6. 1 1 • 1 5. 12. 7. 1 9 . 4 . 6 • 7. 1 o • 1 3. 1 1 . 4 , 1 9 . 4 , 5 . 7. p . 1 2 • 1 1 • 6 • 20 . 3. 4 . 6. 10. 1 1. 1 2. 2 1. 2. 4 . 5 . 3 . 9 , 1 6 • 1 P • 2 5 , 2 . 9 . 20 . 23 . 2 0. 1 • 3 • 5 • 4 • 1 1 • 24. 20 • 31 • 1 • J . 6 . P . IS . 20 , 32 . 3 3. 2. 4 , 7. 1 1 • 2 0. 32 • 3 8 . 33 . 3. 9 . 15. 2 5. 36. 36. 32 . 4 • 6 • 1 0 • 1 7. 2 9 . 3 H , 35 . 29 . 5 . 7. I 1 • 19. 31 • 39. 1 3. 24 . 5. 7 • 1 1 • 19 . 32. 39. 2 9 . IP . 6. 1 c • 18. 32 . 30 . 28 . 12. 4 . 5 • 7. 1 5. 3 1 • 3 0. 2 1 • 5 • 4. 4 . 4 . 1 3 • 3 0 . 35 . 19. 1 . 4 . 3 . 1 • 1 1 • 3 0. 35 . 19 . 4 . 4 • 4 . 3. 1 2 • 3 0 . 35. 2 0 . 7. 4 . 5 • 6 • IS . 3 1 • IS • 20 . 7 . 4 . 6 • 9. 1 0. 3 3. 3 6 . 2 0 . 6 . 3 . 6 • 1 1 • 20. 34 . 36. 2 0 . 5. 3. 6 . 1 1 • 21 • 34. 3 8 , 2 1 • 5 • 2 . 5 • 1 1 • 21 • 33. 38. 2 2 . 2 • 5 • 10. 1 9. 30. 33. 2 3 . 1 2 . 4 . 8. 16. 26 . 3 0 . 23 . 18. 2 . 3. 7. 1 3. 2 1 . 25 « 21 . 1 6 . 2 • J • 5. 9 • 16. 19. 10. 1 5 . 1 • 2 • 3 • 6. 1 0. I 4 , 13. 12 . SHI N-S march 23 Component 1966 67 Figure 16. Result of* multiple Filtering of ANP vertical component, February 5, 1966. GROUP VELOCITY (km/sec) PERIOD (second) 15 40 65 120 3 • 1,7<7 7*7 07 ).'.7H 3 . ? 41 7 . 2 1 1 .1 'Ki 3.174 1 • I * * ' 1 ? . 1.1 2 7.111 7.0 r*0 3 .0^0 1.A40 ?.71fl 2 .7 22 2./>OH Pmt r>? 2 . * ic ?.fon 2 • b 2.5**. *> .£-44 2.t>21 2.£^3 ?.•>«> 2 .4 £* 2. 431 4.5 4.0 3.5 30 2.5 A N P v e r t ic a l c o m p o n e n t February 5 1966 69 dashed lines were drawn through adjacent group arrivals to obtain the approximate group arrivals for these periods. This is feasible because in an average continental dis persion, there are only two group—velocity minima, one at periods of about 15 to 2 5 seconds, and the other at periods of about 250 seconds. On some plots, the distribution of amplitude maxima clearly represent the group arrivals of the funda mental mode (Fig. 17). In those cases, a measurement from the peak—and—trough method is redundant even if applic able. For this reason, group arrivals were chosen from amplitude maxima directly and particularly for periods longer than 80 seconds despite the fact that no waves of such periods can be visually observed on the seismograms. Xn most instances, group velocities were obtained without applying the third step. Values of the group velocities interpreted from the two-dimensional plots are listed in the tables in Appendix V. These two-dimensional plots provide an efficient way of obtaining the observed group velocities since energies from different modes and later arrivals are separated, and structural changes or disturbances along the wave paths can be detected. These characteristics can be demonstrated by the following example: 1. On the plot of NDI, vertical component (Fig. 70 Figure 17. Result of multiple filtering of NDX vertical component, September 28, 1966. GROUP VELOCITY ( k m / s e c ) PERIOD (second) 1 4 35 4 9 6 3 ao 09 9 7 1 0 0 90 94 09 02 NDI vertical component Septem ber 28 1966 ioa.i2o« 120 1 3 • 4. 1 4 . 4 . 14 . 4. 1 0 10. 19 12. 2 1 1 3. 22 15. 24 1 7. 25 1 0. 27 20. 20 21 • 29 22. 30 23 . 3 I 24. 32 25. 32 25 . 33 26. 32 26. 32 26. 31 2 6 . 30 25. 29 25 . 20 24 . 26 23. 25 23 . 23 22. 21 21. 1 9 2 0 . 1 7 1 9. 15 19. 1 4 16. 1 1 1 7. 0 16. 6 16. 5 16. 6 17. 9 10. 12 1 9. 15 21 • 19 24. 23 27 . 27 30. 31 34. 35 30 . 40 4 3 . 45 47 . 49 52 . 60 63 . 64 6 0 . 68 73 . 73 70. 77 32 . 01 06. 04 09 . 60 93 . 94 97. 97 9 9. 99 U * 99. 99 96 . 95 91. 90 as. 04 79. 77 72. 70 65. 61 57. 53 49. 44 41 . 36 34. 29 27. 22 21 • 1 7 15. 1 2 10. 0 7. 7 5. 7 5. 0 6. 4 .2 13 4.1 0 2 4. 1 51 4.1 2 0 4 • 09C 4.061 4 .0 3 2 4 .0 0 3 4 Q 3.575 3. 547 3. 91 9 3. 392 3 .8 6 5 3.0 3 9 3.8 1 3 3.7 0 7 3 .7 6 2 3.7 3 7 3.712 3.66 3 • 640 3.61 7 3. 594 3.571 3 .5 4 3 3.526 3.5 0 4 3 5 3.4 32 2.4 9 9 2.5 9a . 72 17)9 September 28, 1966, small amplitude maxima in the periods of 11 to 15 seconds appear on the upper left—band corner. They are isolated from the slower maxima of the fundamental-mode waves in the lower half of the plot, and are considered higher—mode waves. They correlate to small amplitude, short-period arrivals at the beginning of the fundamental-mode-wave train on the seismogram (Pig. 18). On the lower right-hand corner of the plot, amplitude maxima of longer periods (longer than 50 seconds) also are present. These may be later arrivals or results of slower attenuation of the longer—period waves after the shorter- period waves have diminished. In either case, they can not be observed on the seismogram due to stronger shorter- period waves superimposed on them. 2. On the plot of LAH, N-S component, September 28, 1966 (Pig. 19)9 because of the absence of amplitude maxima to make smooth connections, the dispersion curve is dashed from periods of 28 to 50 seconds. This is be cause waves of these periods arrive with slower velocities as shown in Figure 20* One explanation is that correspond ing to the wavelength of these waves the structure along the wave-path has been disturbed* Therefore, most of the wave energy has taken a non-least-time path and travel with apparently slower velocities. 3. Another correlation between the seismogram and 73 Figure 18. The seismogram of NDI vertical component September 28, 1966. 75 Figure 19# Result of multiple filtering of LAH N—S component, September 28, 1966. 76 GROUP VELOCITY (km /sec) 4. 4-2 5 4. 304 4* 164 4* 334 4* 104 4 • 275 4 • 2 47 4*213 4. 4* 167 4 • 1 36 4.109 4 • 082 4. 05 5 4. O iO 4* 10 5 3 • 96 0 3 • '255 3 • 9 30 3. 0*6 3.932 3* 851 3* 815 1.812 1 • 789 3. 767 3. 74 4 4.0 ► 63 7 . SI 6 , 5^6 3.5 5 . < 4 2 3 . 4 60 3. *47 3.0 2 . T i l 2 . 2^1 2 . 0 ' 1 2 • 7=>9 2 . 77 4 2 . 7 5 0 2.5 ’ • 302 >. 37 > : 114 3 LAH N-S September 28 component 1966 PERIOD (second) 20. 17. 12. 7. 7. d. 0. 13. 2T • 21. 18. 12. 7. 7. 8. 10. 13. 21. 21. 18. 11. 6. 7. 8. 10. 13. 21. 22. 18. 12. 6. 6. 8. 0. 13. 22. 27. 18. 11. 5. 6. 6. 9. 13. 22. 22. 18. 11. 4. 6. 7. 9. 13. 23. 21. 17. 10. 4. 6. 7. 9. 12. 23. 2 0. 16. 9. 3. 5. 7. 8. 12. 23. 19. J.5. 9 . 2. 5. 7. 7. 11. 24. 17. 14. 8 . 2. 5. 6. 7. 10. 24. 15. 17. 7. 1. 5. 6. 6. 9. 24. 1 * . 12. 7. 1. 5. 6. 5. 9. 25. 1 1 . 1 1 . 6. 1. 5. 6. 4. 8. 2 5. 9. IT . 5. 1. 5. 5. 3. 7. 76. 7. 5. 5. 2. 5. 8. 3, 7. 27. 6. 8. 4. 2. 5. 6. 3. 9. 29. 4." 7. 6 . 2. 5. 6. 4. IT . 30. 7. 7. 3. 2. 6. 7. 5. 11. 12. 1. 6. 3. ?• 6. 7. 7. 14. 74. 1. 6 . 3. ?. 6. 8. 9. 16. 77. 7. 5. 3. 3. 7. 9. 11. 19. 39. 7. 5. 3. 3. 8. 1 ). 14. 23. 42. 7. 5. 3. 9. 12. 16. 26. 45. 4. 4. 4. 3. 10. 14. 19. 29. 48. 4. 4. 4. 7. 11. 16. 22. 32. 51. f + . 4. 4. 4. 12. 13. 25. 36. 5 3 . / 4. 3. 4 . 3. 1 3. 20. 28. 39. 5 6./ 4. 3. 5 . 3. 15. 2?. 31. 43. 69./ 4. 7. 5» £• 1 7. 25. 74. 4 6 . 6 1 / 4. 2 . 6. 1. 19* ?6. 7 *. 5 f. 6>* j 4. 7 . 7 . r.. ^ 1 • 3 1. 4 i . S3, / b . i 9 * 4 . P. 7. 24. 36. 45. " 7 . / 6 S. o, 5 . 27. ■ » 9. 49. 6C / 6^ . 3® 3. 11. 8. 31. 42. 5 9 . A • I f . 11. 14. 12. 35. 46. 56. >65. 7rD . / 1 *• 15. 13. 17. 19. 5 ). 6 8./ 19. 2? • 24. 25. 46. 57, /< 5 . 67J '’ 7. 3^ . 15. 3<- • 54. 7 ^ r 75, *61 35, 4 1. 43. 4 5. 6 ^ / 7 0 o. 7 8 • o /, -7 . 53. 5 5. 5 6 - ^ 71* . 7 X * • 5 9. 6 4 . ^ 7 T T T . 7 ^ 8 3 . 85. 83J./64. "71. 7> . 7 8. 7 8 8. 9 0 . 8cU 87. 91. 9 7. 93. 8 91. 9^* 26. 94, 95. 96. 9 6. 921 74.1 ^7, 98. 99. 99. ^8 . 9 5 .X ^ 9 .\ 79* 1 Cl • 1 C'0. 1 00. 1 Oo. op. > 5 ^ 0 6. 7 . 99. i r o . m p . i r o . oo. j i ,6 . 8 5. 8 9. 94.1C0.1 -~rrr\ a r . 3 6 * 7 ^ 7 9 V *^ S 3 . 9 • ‘‘ 7 .1 4 3. 29. 24. 31 , V 6 • 72. 77>v64. ) 4 • 7 7 • 21 o 13. 42. TT*—>5rZ>^Z2s 7^ X P B • 31 o 16. 6 . 34. 89. 57. . M2. >7. ! 3. 7. 27. 42. 5 C. 55. 2 7. 1 -. 11. 21. 36. 4 "a. 47. 54. 5H* 2 9. 15. 15. 16. 30. 3 7. 40. 46. 34. 19. 19. 12. 26. 3 2. 33. 38. 53. 4 *. 25® ’ 1 * 10. 23. 26® 27. 31. u7. 4 7 3 3 f. 2 7. 10. 21. ^4. 21. 24. u1 . •_,4. 34. 2b. '13. 2). 22. 16a 18. 76. * v« , 0 . 76. 15; 19c 2 0* 12? 13- -»P. 65. j >0 26. 18, 19, IB . 17. 9. 79. - O *9. 24. 21. 2 1. 13. 9. 8. 28. 7 . J7 . 22. 9 3. LV • 18. 11. 9. 27. 7 ‘ . ? ^ , 1 °. 24. 71. 19. 13. 1 *. 26. 67. 2 9. 14. 25. 21. 19. 16. 16. ? ^ • c*® 2'3 a 1^. 25. o1# ? ? # ip . 19. 27. " . *» * o 17. 24. 21. 27. 2 . 21. 76® 77 Figure 20• The seismogram of LAH N-S September 28, 1966* 78 ! m — . -A h CQ M P j?_a T. IS ^J20_rRM 3 MOT J i 79 66 36 th.e two-dimensional plot is tiiat tile rate of amplitude change with time on the seisinogram partly reflects the rate of group velocity change with period* This is depicted by the plots of NDX, N-S component, September 28, 1966 (Fig. 2l) and ANP, February 7> 1966 (Fig. 22) for the period range of 11 to 28 seconds. The slope of the group velocity in Figure 21 is steeper than that in Figure 22. The cor responding seismogram of Figure 21 shows slower amplitude descent (Fig. 23) than that of the corresponding seismogram in Figure 24. From the two-dimensional plots and tables of group velocities, it is noted that group velocities obtained from different wave—paths show quite divergent values, whereas those observed from similar wave-paths are not significant ly different from one another. The differences and similarities can be partly illustrated by comparing the following values on each plot: (l) the maximum value of group velocities, (2) the minimum value of group velocities and (3) period range of steeper slopes of group velocities and changes of group velocities in these periods. Values of these items are listed on Tables 6 to 8. For an easy comparison they have been separated into three groups ac cording to their geographic locations. These are: eastern China, Tibetan platform, and central China groups. An examination of these tables discloses the following: 80 Figure 21. Result of multiple filtering of NDX N-S component, September 28, 1966. GROUP VELOCITY Ikm/sec) PERIOD (second) . 7 i . 39 . m . /if,. 15 40 65 120 4.0 3.5 3.0 NDI N -S com ponent Sept. 2 8 1 9 6 6 82 Figure 22. Result of multiple filtering ANP N-S component, February 7 1966. GROUP VELOCITY (km/sec) PERIOD (second) 28m 31 . 3 5 . 4?. 4 6 . 50 . 5 5 . 6 2 . 6 6 . 71, «9 . 9 8 . | o n . 1 2 0 . 120 4 .0 9 6 3 .9 44 2 .7 7 0 ANP N-S Component February 7 , 1966 84 Figure 23 # The seismogram of NDI N-S com ponent, September 28, 1966. 85 ~STA M Di COMP M -s DATF %F 14b trap T . 1 5 - T n 1 C - G RKD MQ7.± Figure 24. The seismogram of4 ANP N—S ponent, February 7* 1966. com— 87 88 Table 6. Tibetan platform group Rayleigh Wave Maximum G.V. Minimum G.V. Compo- Velocity Period Velocity Period Wave Path nent (km/sec) (second) (km/sec) (second) Velo. range Per. range LAH Feb. 5, 1966 Z 3.617 76 2.594 13 2.617-3.484 15 - 50 NDI Feb. 5, 1966 Z 3.770 98 2.772 13 2.793-3.581 22 - 39 LAH Sept. 28, 1966 Z 3.595 120 2.314 11 2.314-3.496 11 - 89 LAH Aug. 30, 1967 Z 3.468 89 2.601 28 2.601-3.411 33 - 76 CHG June 15, 1971 z 3.489 120 2.658 18 2.658-3.435 22 - 66 NDI Sept. 28, 1966 z 3.684 98 2.6l4 18 2.628-3.640 22 - 76 NDI Jan. 18, 1967 z 3.583 98 2.753 13 2.879-3.413 25 - 46 Love Wave NDI Sept. 28, 1966 N-S 3.846 108 2.763 12 2.763-3.694 12 - 55 LAH Sept. 28, 1966 N-S 3.722 ___ ..3.Q&7_ 13 3.069-3.701 „ 13 - 62 oo ^0 Table 7. Eastern China group Rayleigh Wave Compo nent Maximum G.V. Minimum G.V. Velo. range Per. range Wave Path Velocity (km/sec) Period (second) Velocity (km/sec) Period (second) IiKC Jan. 18, 1967 Z 3.829 120 2.817 13 3.17 -3.700 25 - 40 SEO Feb. 13, 1966 z 3 • 668 76 2.847 15 2.90 -3.500 22 - 42 SEO Feb. 5, 1966 z 3.386 ANP Feb. 5, 1966 z '3.768 62 2.900 15 3.00 -3.620 33 - 46 ANP Feb. 13, 1966 z 3.680 55 2.854 15 2.85 -3.600 15 - 46 HKC Jan. 20, 1967 z 3.720 62 2.871 12 2.915-3.640 18 - 50 Love Wave HKC Jan. 18, 1967 E-W 4.17 76 3.0 11 3.34 -4.04 25 - 50 ANP Feb. 5, 1966 N-S 4.086 108 3.150 12 3.172-3.914 13 - 46 ANP Feb. 13. 1966 N-S _ ^223...- ___ ... 3.290 . 23 . . 3.336-3.964 18 - 50 vo o Table 8. Central China group Rayleigh Wave Compo nent Maximum G.V. Minimum G.V. Velo. range Per. range Wave Path Velocity (ion/sec) Period (second) Velocity (km/sec) Period (second) LAH March 7, 1966 Z 3.533 108 2.820 12 3.092-3.^55 39 - 66 ANP Feb. 7, 1966 Z 3.849 76 2.621 11 2.621-3.826 11 - 71 SEO Feb. 7, 1966 Z 3.580 76 2.728 11 2.771-3.556 11 - 66 CHG June 16, 1973 Z 3.5H 62 2.911 15 3.105-3.488 18 - 46 CHG Jan. 18, 1967 Z 3.670 120 2.895 39 2.939-3.647 42 - 98 CHG Jan. 20. 1967 z . . . 3.592 89 2.951 15 2.995-3.523 18 - 71 Love Wave LAH March 23, 1966 N-S 4.065 108 3.137 13 3.220-4.024 18 - 89 SHI March 23, 1966 N-S 3.912 120 2.962 13 3.024-3.699 13 - 62 ANP Feb. 7, 1966 N-S 4.070 120 3.072 12 3.293-3.803 28 - 50 CHG June 16, 1973 0 • CO - " 3 76 3.303 15 3.327-3.832 28 - 55 CHG Jan. 20, 1967 E-W . . 3.075 . 120 2.827 11 2.827-4.055 11 - 98 V v0 H 1. Group velocities in the eastern China group are, in general, higher than the other two groups with the maximum values of group velocities in the neighborhood of 3#70 km/sec for the Rayleigh wave and 4.10 km/sec for the Love wave. Minimum values are in the vicinity of 2.83 km/ sec for the Rayleigh wave and 3*1 km/sec for the Love wave. Steep slopes of group velocities are in the period range from 20 to 43 seconds. 2. Group velocities in the Tibetan platform group are usually the lowest among all three groups with the maximum values of group velocities in the neighborhood of 3.35 km/sec for the Rayleigh wave, and 3.77 km/sec for the Love wave. The minimum values are approximately 2.63 km/ sec for the Rayleigh wave and 2.9 km/sec for the Love wave. The steep slopes of group velocities in this group on the average range from 18 to 63 seconds, which is broader than the other groups. The change of group velocities in this range is approximately 0.8 km/sec which also is greater than the other two groups. 3. Group velocities and all the characteristics in the Central China group are, almost without exception, intermediate to those high values of eastern China group and low values of Tibetan platform group. More detailed descriptions of these two-dimensional plots will be presented in a subsequent chapter when the structure of each region is discussed. 92 Regionalization General Regionalization was first proposed by Toksoz and Anderson (1966) in dividing a wave-path into oceanic, shield, and mountain-tectonic regions because these regions have different effects on the average of phase and group velocities* They noted that shield areas raise the average phase velocity; tectonic and mountainous areas have the opposite effect* Moreover, they proposed that the tectonic-shield distinction is equally as important as the more obvious continental-oceanic distinction* Xt was mentioned in the preceding section that group velocities obtained from wave—paths crossing different re gions of China show quite divergent values* This must be a result of dissimilar tectonic characteristics in the various regions. In order to analyze regional variations, the idea of regionalization is adopted so as to derive pure-path group velocities in each region* To achieve this end, not only the availability of the group velocit ies from composite wave-paths is necessary, but also the proportion of each region in the composite path has to be predetermined* Regional boundaries in China are drawn on the basis of the following: (l) Bouguer gravity distribu tions, (2) physiography, and (3) group velocity data from available wave—paths. 93 1. Bouguer gravity distribution; As noted in the introduction, wide variations of Bouguer anomalies are present in the areas of China (Fig. 6). Because the Bouguer anomaly reflects the mass deficiency below the sea level, its variation indicates the change in mass distri bution below the sea level, which implies the change in crustal and upper mantle structures. Therefore, zones of high Bouguer gravity gradients are considered structural boundaries. On this basis, two regional boundaries (Fig. 6) are obvious: one is along the north and east side of the Tibetan platform where values of the Bouguer gravity change rapidly from —550 to -200 milligals toward the north and east. The other is along a north—northeast trending mountain—belt in eastern China from latitude N 30° to N 45° where Bouguer anomalies change rapidly from -40 to —lOO milligals toward the west. 2. Physiography: It is evident from the physio graphic map (Fig. l) and geologic map of China (Fig. 25) that the regional boundaries defined by the Bouguer gravity changes are also physiographic boundaries. In the Tibetan platform and northeastern China, the Bouguer gravity gradient coincides with the transition from mountainous areas to topographic basins. Likewise, a new regional boundary can be drawn for the same physiographic transition at 30° N latitude and striking east—west. Furthermore, this boundary can be extended westward to con- 94 1 T1 " P ‘ ' C r g o 1 o ■ ■ r ri c ol rh .nc 95 geology OF mainland china r e p r o d u c e d f r o m t h e t e c t q n ic m a p o f c h in a AND MONGOLIA PUBLISHED BY THE U.SG s I B 74 < P Z U N G A R I A N \ i v % » " ^ V r „ T X 1 | M JktSffeife' ^ 7 ® d 4 -.V' F , f-£v*‘>V ',' 'i/' - 1 ' / ' 'J -.^ iw , fdM-S1 ®7 / / / ' ' l ' / / / Z . C D 0 > • **F^f ’i ‘ •;^h ysy > ' ' ? / / ■ <u9 f &i%v J * ■^ T A R I M S T A B L E BL O C K ® . v ® : • ALA 5 H s t a b l e b l o c k '■ c-L-.?'*;.'. '•.’- ." • . v % ^ s , ORDOS , . . ^ r I b a s i n . y / ' ’ t' 1 ' I* " : . ' / 4 0 if** T ' b e Ta n . , y ; , S Z E C H W A N 8AS-4-N - l l | T o r r e a t r is l b a s a lts & sn d o s its Geem D epoeite-continent A elastic de po sits G eosynclinal Deposits marine sediments T e r r a a t r ia l r h y o llte e F©ia»c igneous intrue y'\ granites igneoue SCALE I 5 .0 0 0 .0 0 0 *19 . < H i ii _ _ _ ii i n u aim != » » '9.9... ■ iiia m ii ,n u ,„? L ..iP # □ O u flte rn e ry & T e rtia ry loaee and allu visl deposits O r Jure ssic & C re ta ce o u s deposit in ea ste rn C hins J IW eekly m etam orphosed rocks ] U ltra m a fic [ V V r ^ j slates. Pfyllites* I ^ ✓ | .ntru3ives S tro ng ly m etam orphosed rocks ^ « l • _ | • 4 _ ScWsts, gneiss * ^✓PnlOlltCS nect with, the regional boundary on the north edge of* the Tibetan platform. In northern China, physiographic and structural contrast can be seen along the southern rim of Mongolia, where intensely faulted Precambrian and Paleozoic meta- morphic and basic igneous rocks in Mongolia merge with dominantly more acidic igneous rocks to the east and Quaternary sedimentary rocks to the south* Therefore, the border between Mongolia and northern China is considered a regional boundary* 3# Group velocity data from available wave-paths: If there are no pure—path group velocities for some com ponent regions, characteristics for individual regions can not be studied even if group velocities of composite wave- paths are available* Fortunately, pure-path group velocities are available for the Tibetan platform and the southeastern China areas. Using these data and group velocities of composite wave-paths across northwestern, northeastern, and central China, pure-path group velocities of individual regions can be deduced* Furthermore, if data from several wave-paths are available for a region, estab lished boundaries can be adjusted and new boundaries may be defined. This is true because pure-path group velocities deduced from different wave-paths for the same region should be compatible. Using this approach, central China (latitude 30° to 97 40°) are divided into two regions because pure-path group velocities for central China deduced from wave-paths east of 100° E longitude are appreciably greater than those deduced from wave-paths west of the same longitude line* Xn summary, on the basis of the three criteria con sidered, China and Mongolia are divided into six distinct regions as shown in Figure 26, They are: Region I: Tibetan Platform Region IX: Southeastern China Region XII: Northeastern China Region IV: Central China Region Y: Northwestern China Region VI: Mongolia Calculations and Test of the Regionalization In using the regionalization, it has been assumed that over-all group velocity is the path—weighted linear sum of each of the regional group velocities (Toksoz and Anderson, 1966), That is, if a composite wave—path, with path—length L, consists of two regions, each has a group velocity U^, Ih, and a path-length of , then the over all group velocity is given by the relation: L/U = L1U1 + L2/U? ox- l/U = L1/L/U1 + L2/L/U2 = P1/U1 + P2/U2 Figure 26. Regional division of China and Mongolia. 99 \ < f e rQ I path, percentages of each region. Conversely, a regional group velocity can be calculated from this formula if group velocities of one region and the over-all are known. The present data, because of the availability of separate wave-paths across the Tibetan platform, southeast China, and across the entire southern China (Fig. 27)» provides a chance to test the linearity of the regionaliza tion for possible variation due to boundary effect. Previously it was observed that group velocities obtained from wave-paths crossing the Tibetan platform are very low, and paths crossing eastern China are relatively high. Xf the boundary effect is not severe, then group velocities obtained from wave-paths crossing both regions should be intermediate between the high values of eastern China and the low values of the Tibetan platform. It is shown in Figure 28 that this is indeed the case. Values of ANP February 7* 1966 (representing average of two regions, path 3 in Figure 27) are between those low values of CHG June 11971 (representing the Tibetan platform, path 4 in Figure 27) and those high values of ANP February 5, 1966 (representing southeastern China, path 1 in Figure 27)• Similar results are shown in Figure 29 for Love waves. To pursue this analysis one step further, over—all Love-wave group velocities for southern China are calculat ed by the relationship (l) using the results of ANP Febru ary 5* 1966 as 45 percent path—length, and NDX September 28, 101 Figure 27* Pure and composite wave-paths of southeastern China, 102 103 v i ■ EPICENTER i O WWNSS MONGOLIA y Y E L L O ^ SEA SHANGHAI CHINA SEA >ANP O S O HOW HKC SOUTH CHINA SEA BAY OF CH$ BENGAL 90 100 Figure 28. Comparison of* Rayleigh wave group velocities for the low values of Tibetan platform, high values of southeastern China, and intermediate of the average from these two re gions. 104 GROUP VELOCITY (k m /sec) RAYLEIGH WAVE DISPERSION 4.25 4 .0 0 3.75 3.50 3.25 3.0 0 2.75 0 20 4 0 6 0 8 0 100 I2C PERIOD (sec) ......1 ......1..“T" D ~1 □ □ □ □ 0 ......i....... ...._i........... — OO ° o □ □ _ O O ° 0 0 e 0 ° ° e ° O — □ 0 © o © ' 0° n ° c □ © _ o° 6 oResult of ANP vertical comp Feb 5, 1966 oResult of ANP vertical comp Feb 7, 1966 © ©Resuit of CHG vertical ~ J_- J ___1 _ comp June 15, 1971 1 i - l __i 1 i 1 i 105 Figure 29# Comparison of Love wave group velocities for the low values of Tibetan platform, high, values of southeastern China, and intermediate of the average from these two re gions . 106 GROUP VELOCITY (k m /s e c ) LOVE WAVE DISPERSION 4.4 4.0 0 © © © © • * 0°?o 0 0 o o §00 © o 3.6|— # Q 0 0 a O 0 ^ ® Result of N-S comp ANP Feb. 5,1966 - z o L O 0 ^ 0 Resu^ N-S comp LAH *** 0 ° March 23, 1966 Q 0 Result of N-S comp NDJ *0 Sept. 28,1966 2.8 0 20 40 6 0 80 100 120 PERIOD (sec) v . O <1 1966 as 45 percent path—length, and NDI September 28, 1966 as 55 percent path—length. Comparison of calculated values with those observed over—all values of LAH March 23, 1966 (path 5 in Fig* 27) are shown in Figure 30* Apparent are the differences, yet in general they are less than 0,1 km/sec or 2,5 percent. In Figure 31, similar comparison is shown for the Rayleigh waves. Differences commonly are less than 0.2 km/sec or 5 percent. Considering the 1 per cent error in determining the observed group velocities and a possible amplification of error in the calculations, these differences are tolerable. However, divergent differences in different periods may have resulted from inhomogeneities in each region and diffractions across regional boundaries. These results indicate that the regionalization by the relationship (l) is an approximately valid scheme in dividing the over—all group velocities of a wave—path into its component regional group velocities. Application of the Regionalization No pure—path group velocities are available from direct observations for the northeastern, central, north western China, and the Mongolia regions. Therefore, re gionalization was utilized to deduce the pure—path group velocities from composite wave—paths for these regions. They were calculated in the following manner: repre sents the over-all or composite group velocity, and U is 108 Figure 30* Comparison of Love wave group velocities from calculation by re gionalization technique and from composite wave path.. GROUP VELOCITY (km /sec) 4.4 2.8 LOVE WAVE DISPERSION 4 . 0 - ' + + + + + _ o 0 * , o O + o * + ■ 3.6 h + + o + Result of LAH N-S + 0 comp March 23,1966 32I — + ° ° 0 Calculated from NDI N-S * + Sept. 28, 1966 and ANP N-S comp Feb. 5, 1966 by using path-weighed regionalization I I I _____I_____I__ 0 25 50 75 100 125 150 PERIOD (sec) O Figure 31, Comparison of Rayleigh wave group velocities from calculation by re gionalization technique and from composite wave path. Ill t+t t 1 A A Result of ANP Vert. Comp. February 7» 1966 Calculated from LAH Vert. Comp. August 30, 1967 and ANP Vert. Comp. February 5, 1966 the unknown pure—path group velocity to be calculated. Xf we assume has path—length percentage , and U has path-length P, then we have 1/U2 = + p/u or P/U = 1/U2 - V U1 u/p = i/(i/u2 - Pj/up or U = p/(i/u2 - I^up P and P^ can be measured from a map once the regional boundaries are defined, and and are obtained from the two-dimensional plots. Therefore, the unknown pure—path regional group velocity U can be calculated. Tables 9* 139 15* and 20 give the relevent data used in the region alization computation for, respectively, the northeastern China, central China, northwestern China, and Mongolia. Their corresponding calculated group velocities are given in Tables 10 to 12, lb to 16, 18 to 19* and 21 to 23* Crustal and Upper Mantle Structures General Statement From physiographic expressions, Bouguer gravity, and group velocity dispersion information, we have divided the mainland China into five regions having characteristi cally different crustal structures. Each of these regions plus Mongolia was investigated by use of surface wave dis persion data obtained in previous sections. Particular 113 Table 9* Data used for the calculation of pure-path group velocities of northeastern China (Region 111) Over—all Wave Path Other Regional Wave Path Path per centage Path—length percentage of this region (Region III) HKC J an. 18, 1967 ANP Feb. 13, 1966 (Region IX) hy/o 57 ° / o HKC Jan. 18, 1967 ANP Feb. 5, 1966 h3°/o 57 ° / o SEO Feb. 13, 1966 ANP Feb. 13, 1966 Ukfo 56$ 11^ Table 10. Pure path, group velocities of* northeastern China Rayleigh Wave Period U1 U2 U 120. 5 3.710 3.852 3.906 107.8 3.651 3.829 3.898 97.5 3.623 3.805 3.876 89.0 3.593 3.762 3.827 81.9 3.540 3.741 3.820 75.9 3.513 3.719 3.800 70.6 3.513 3.698 3.770 66.1 3.567 3.698 3.748 62.1 3.623 3.698 3.726 55.4 3.680 3.719 3.733 50.0 3.651 3.719 3.744 ^5.5 3.595 3.698 3.737 41.8 3.460 3.677 3.763 38.6 3.288 3.635 3.780 32.5 3.198 3.516 3.648 28.1 3.101 3.213 3.256 24.7 3.060 3.192 3.243 22.0 3.001 3.192 3.268 18.1 2.872 3.085 3.171 15.4 2.837 3.037 3.117 13.4 2.917 2.817 2.782 11.8 2.963 2.858 2.822 10.6 2.944 2.901 2.886 U = Northeastern China, 73* Ux = ANP February 13, 1966, 26.7° / ° U2 = HKC January 18, 1967, 100^. 115 Table 11. Pure path group velocities of northeastern China Rayleigh Wave Period U1 U2 U 120.5 3.710 3.647 3.599 107.8 3.651 3.626 3.607 97.5 3.623 3.647 3 • 666 89.0 3.593 3.668 3.729 81.9 3.540 3.668 3.775 75.9 3.513 3.668 3.780 70.6 3.513 3.668 3.780 66.1 3.567 3.647 3.712 62.1 3.623 3.647 3.666 55.** 3.680 3.647 3.621 KJ\ o • o 3.651 3.626 3.607 45.5 3.595 3.606 3.615 41.8 3.460 3.556 3.635 38.6 3.288 3.498 3.683 32.5 3.198 3.361 3.501 28.1 3.101 3.210 3.301 24.7 3.060 3.094 3.121 22.0 3.001 2.945 2.902 18.1 2.872 2.873 2.874 15.4 2.837 2.847 2.855 13.4 2.917 2.847 2.794 11.8 2.963 2.986 3.004 lO. 6 2.944 2.986 3.020 U = Northeastern China, 56^> • = ANP Vertical Component February 13, 1966, 44 ° / o . = SEO Vertical Component February 13, 1966 , 100? ; 116 Table 12* Pure patb group velocities of northeastern China Love Wave Period ui U2 u 120.5 107.8 4.026 97.5 4.070 89.0 4.051 81.9 4.016 4. l4l 4.24o 75.9 3.921 4.141 4.323 70.6 3.981 4.115 4.222 66.1 3.981 4.115 4.222 62. l 3.981 4.115 4.222 55.4 3.964 4.089 4.188 50.0 3.931 4.037 4.120 45.5 3.866 3.963 4.039 41.8 3.787 3.868 3.931 38. 6 3.697 3.799 3.879 32.5 3.543 3.608 3.658 28.1 3.451 3.485 3.5H 24.7 3.401 3.358 3.326 22.0 3.353 3.262 3.197 18.1 3.283 3.257 3.238 15.4 3.183 3.230 3.266 13.4 3.183 3.224 3.255 11.8 3.152 3.182 3.205 10.6 2.945 3.182 3.386 U = Northeastern China, 57°/°• V± = ANP February 5, 1966, hy/o. U2 = HKC January 18, 1967, IOO° / o 117 Table 13. Data used for the calculation of pure-path group velocities of central China (Region IV) Over—all Wave Path Other Regional Wave Path Path per centage Path-length percentage of this region (Region XV HKC Jan. 20, 1967 ANP Feb. 13, 1966 (Region II) 50% 50 f a NDI March 7, 1966 June 15, 1971 (Region X) 57/£ hy/o CHG Jan. 20, 1967 June 15, 197X 60 ° / o kOc / o 118 Table 14. Pure path, group velocities of central China Rayleigh Wave Period U1 U2 u 120.5 3.710 3.465 107.8 3.651 3.563 3.479 97.5 3.623 3.614 3.605 89.0 3.593 3.640 3.688 81.9 3.5^0 3.640 3.746 75.9 3.513 3.666 3.833 O • 3.513 3.666 3.833 66 • 1 3.567 3.693 3.828 62.1 3.623 3.693 3.766 55.4 3.680 3.666 3.652 0 • 0 m 3.651 3.6l4 3.578 45.5 3.595 3.563 3.532 41.8 3.460 3.513 3.568 38.6 3.288 3.465 3.662 32.5 3.198 3.396 3.620 28.1 3.101 3.351 3.645 24.7 3.060 3.007 2.956 22.0 3.001 2.983 2.965 H • 00 H 2. 872 2.893 2.914 15.4 2.837 2.915 2.997 13.4 2.917 2.871 2.826 00 • H H 2.963 2.871 2.785 \D • O H 2.944 2.515 U = Central China, 50 ° / o0 V± = ANP February 13, 1966, 50 ° / o . U2 = HKC January 20, 1967, 100°/o. 119 Table 15* Pure path group velocities of* central China Raleigh Wave Period ui U2 U 120.5 3.489 3.573 3.692 107.8 3.458 3.573 3.739 97.5 3.458 3.594 3.793 89.0 3.458 3.594 3.793 81.9 3.458 3.616 3.851 75.9 3.458 3.616 3.851 70.6 3.458 3.594 3.793 66.1 3.435 3.573 3.775 62.1 3.369 3.531 3.772 55.4 3.305 3.444 3.649 50.0 3.217 3.318 3.463 b5.5 3.140 3.202 3.289 41.8 3.091 3.093 3.096 38.6 2.986 2.987 2.988 32.5 2.881 2.939 3.020 28.1 2 . 840 2.804 2.757 24.7 2.799 2.783 2.762 22.0 2.750 2.762 2.778 18.1 2.658 2.762 2.914 15.4 2.635 2.783 3.008 13.4 2.635 2.848 3.192 11.8 2.635 2.870 3.257 10 . 6 2.848 U = Central China, k2.86°/o. V ± = June 15, 1971, 57.14$. U2 = NDI March 7, 1966, 100$. 120 Table 16. Pure patb group velocities of central China Rayleigh ¥ave Period ui U2 U 120.5 3.489 107.8 3.458 97.5 3.458 3.592 3.814 89.0 3.458 3.592 3.814 81.9 3.458 3.569 3.750 75.9 3.458 3.546 3.687 70.6 3.458 3.523 3.625 66.1 3.435 3.500 3. 602 62.1 3.369 3.456 3.595 55.4 3.305 3.413 3.589 50.0 3.217 3.371 3.632 45.5 3. l4o 3.330 3.662 41.8 3.091 3.251 3.525 38.6 2.986 3.214 3.630 32.5 2.881 3 • l4l 3.633 28.1 2.840 3.000 3.277 24.7 2.799 2.990 3.247 22.0 2.750 2.950 3.3H 18. 1 2. 658 2.946 3.518 15.4 2.635 2.957 3.621 13.4 2.635 3.021 11.8 2.635 3.H1 10.6 2.840 U = Central China, 40?o. = CHG June 15, 1971, 60° / o . U2 = CHG January 20, 1967, 100^. 121 Table 17* Data used for the calculation of pure-path group velocities of northwestern China (Region V) Over—all Wave Path Other Regional Wave Path Path per centage Path-length percentage of this region (Region V) ANP Nov. 13, 1965 ANP Feb. 13, 1966 55% hy/o NDI Jan. 18, 1967 June 13, 1971 22.8$ 27.8$ Mongolia 50$ 122 Table 18. Pure path, group velocities of northeastern China Rayleigh Wave Period U1 U2 U 120. 5 3.710 107.8 3.651 97.5 3.623 89.0 3.593 81.9 3.540 3.510 3.481 75.9 3.513 3.510 3.487 70.6 3.513 3.531 3.549 66»X 3.567 3.531 3.496 H • CM VO 3.623 3.531 3.444 55. 4 3. 680 3.531 3.394 50.0 3.651 3.531 3.419 45.5 3.595 3.510 3.429 00 • H 3.460 3.484 3. 508 38.6 3.288 3.288 3.288 in • CM cn 3.198 3.H0 3.027 28.1 3.101 3.069 3.038 24.7 3.060 2.931 2.812 O • CM CM 3.001 2.931 2.864 18.1 2.872 2.906 2.931 15.4 2.837 2.975 3.127 13.4 2.917 3.024 3.139 00 • H H 2.963 3.113 3.279 10.6 2. 944 3.089 3.249 U = Northwestern China, h5°/o. V± = ANP February 13, 1966, 55^. U2 = ANP November 13, 1965, 100G / o . Table 19* Pure path group velocities of Mongolia and northwestern China Rayleigh. Wave Period U1 U2 u 120.5 3.489 3.594 3.625 107.8 3.458 3.594 3.635 97.5 3.458 3.583 3.620 89.0 3.458 3.561 3.592 81.9 3.458 3.539 3.563 75.9 3.458 3.517 3.534 " ' ■ i 0 • ON 3.458 3.517 3.534 66.1 3.435 3.4-96 3.514 62.1 3.369 3.496 3.534 55.4 3.305 3.475 3.527 50.0 3.217 3.454 3. 528 45.5 3.140 3.413 3.500 41.8 3.091 3.393 3.490 38.6 2.986 3.389 3.525 32.5 2.881 3.297 3.439 28.1 2.840 3.161 3.266 24.7 2.799 2.900 2.930 22.0 2.750 2.879 2.918 18.1 2. 658 2.858 2 . 921 15.4 2.635 2.776 2.819 13.4 2.635 2.753 2.765 11.8 2.635 2. 816 2.872 10.6 2.900 U a s Mongolia and Northwestern China, 77.8%. V ± = June 15, 1971 (Tibetan), 22.2%. = NDX January 18, 1967* 100%. 124 Table 20. Data used for tbe calculation of pure-path group velocities of Mongolia (Region Vi) Over—all Wave Patb Other Regional Wave Path. Path per centage Path-length percentage of this region (Region VI) CHG June 16, 1973 CHG Jan. 20, (Region X and 1967 IV) 62.5 % 37. y/o CHG June 18, 1967 CHG Jan. 20, (Region I and 1967 XV) 66.7° / ° 33.3°/° CHG June 16, 1973 CHG June 15, 1971 zy/o 62. y/o Central China 12.5$ 125 Table 21. Pure path, group velocities of Mongolia Rayleigh Wave Period U1 U 2 U 120.5 3.670 107.8 3.647 97.5 3.592 3.624 3.640 89.0 3.592 3.601 3.606 81.9 3.569 3.557 3.551 75.9 3.546 3.513 3.497 70.6 3.523 3.471 3.446 66»1 3.500 3.409 3.365 62.1 3.456 3.316 3.250 55.4 3.413 3.202 3.106 O • O in 3.371 3.116 3.002 45.5 3.330 3.031 2.901 41.8 3.251 2.939 2.804 38.6 3.214 2.895 2.758 32.5 3.141 2.920 2.821 28.1 3.152 2.916 2.811 24.7 3.152 2.984 2.907 22.0 3.H7 3.054 3.023 H 00 H 2. 946 3.116 3.209 15.4 2.957 3.137 3.235 13.4 3.021 3.158 3.231 C O • H H 3.1H 3.163 3.190 V O • O H 2. 840 3.099 3.247 U = Mongolia, 33*3/^. U.^ = CHG January 20, 1967* 66.7/£. = CHG January 18, 1967* 100^. 126 Table 22. Pure path group velocities of Mongolia Rayleigh Wave Period ui U2 U3 U 120.5 3.489 3 . 5 H 107.8 3.458 3 . 5 H 97.5 3.458 3 . 5 H 3.814 3.477 89.0 3.458 3 . 5 H 3.814 3.477 81.9 3.458 3 . 5 H 3.750 3.488 75.9 3.458 3 . 5 H 3.687 3.499 70.6 3.458 3 . 5 H 3.625 3.510 66.1 3.435 3 . 5 H 3.602 3.524 62. 1 3.369 3 . 5 H 3.595 3.554 55.4 3.305 3 . 5 H 3.589 3.585 50.0 3.217 3 . 5 H 3.632 3.619 45.5 3.140 3.488 3.662 3.614 oo « H 3.091 3.397 3.525 3 . 5 H 38.6 2.986 3.375 3.430 3.509 32.5 2.881 3 . 3 H 3.433 3.456 28.1 2.840 3.290 3.277 3.516 t- • CM 2.799 3.250 3.247 3.475 22.0 2.750 3.133 3.331 3.277 18.1 2.658 3.130 3.518 3.291 15.4 2.635 2.911 13.4 2.635 2.994 11.8 2.994 vo • o H 3.082 U = Mongolia 62.5#. V± = CHG June 15, 1971, 2 5%. U2 = CHG June 16, 1973, 100 ° / o . U„ = Central China, 12. 5 % J 127 Table 23. Pure path, group velocities of Mongolia Love Wave Period u i U2 U 120*3 *1.075 107.8 4.075 97.5 4.055 89.0 3.995 ON • H 00 3.910 3.874 3.815 75.9 3.854 3.874 3.908 70*6 3.775 3.874 4.051 66 * 1 3.698 3.874 4*208 62.1 3.674 3.853 4*194 55.4 3.601 3.833 4*294 50.0 3.555 3.677 3.900 45.5 3.459 3.553 3.722 00 • H 3.450 3.529 3.669 38.6 3.437 3.505 3.625 32*5 3.243 3.4l4 3.743 28*1 3.193 3.370 3.713 24*7 3.224 3.327 3.514 22*0 3.157 3.307 3.591 18.1 3.121 3.317 15.4 3.019 3.306 3.668 13.4 2.934 3.300 11*8 2.848 3.245 10*6 2.913 3.220 U = Mongolia, 37.5%. = CHG January 20, 1967, 62*3%• U2 = CHG June l6, 1973, 100%* 128 emphasis, of course, is placed on the nature of their crustal and upper mantle structures. Where a pure—path configuration is possible, like the Tibetan platform and the southeastern China, the interpretation is straight forward. For the rest of the regions, where only mixed- path surface-wave data are available, it is then necessary to make use of the idea of regionalization as discussed in the preceding section. When group velocities are being inverted for an earth*s structure, model fitting process for a pure—path case were made to within 0.04 km/sec of the observed group velocities, whereas for a mixed—path case, because of pos sible error in the calculation of pure—path velocities, 0.2 km/sec is the usual standard error of fitting. These correspond to about 1 percent and 6 percent in precision, respectively. Observed group velocities in China and Mongolia are, in general, appreciably lower than those of average con tinental structure (Fig. 32), which corresponds to a thicker crust in some regions (Tibetan platform, north western China, and Mongolia), and more prominent low— velocity zones at shallower depths in others (Tibetan platform, southeastern China, and northwestern China). Lateral inhomogeneities in crustal structures are present in each of the six regions. For lack of sufficient data, however, no attempt was made to further divide these 129 Figure 32. Comparison of Rayleigh wave dis persions from the China areas found by this study and average values of earth observed by others. 130 GROUP VELOCITY (km /sec) _ !>♦ ♦ A*' >v CF 1 l 1 <0‘ o « — < > * > 0 0 • Q ° a l V BODOTP'^ L • - o o 0" o < $ 0 ^ 0 > 0 * » . 4 * • • n o 0 f t o0 < ^ v HJS D°1 • [o 0 A . » 0 * 1 G3 6 1 1 D i k ( 5 “ * )D MAN coV TLE • p * f (. Contnlenti a l 1 i “ < > o _ $ 'Ocearl i e Oc Co Me e c n t i n i n i n t l ( i c - Ewing ental-Pres Ewing a and P s , Ewii nd Pr< ress ig-i ;ss 1 1 9 n p 952 54 ress — a 0 Res Res s u i t s u i t Mil I 1 ill from NDI vertical component Sept 28,1? from CHG vertical component June 15,I S 111! ... 1.d__L . _L_L_ 36 I 6 ( 6 10 50 100 500 1000 PERIOD (sec) I — 1 C O regions into subregions* Tibetan Platform This region is characterized by the low Bouguer gravity and high topographic altitude represented by east- west trending mountain belts, turning to north—south direction on the east side. This region is bounded by the Himalayas to the south and the Kun-Lun mountain range to the north; its western and eastern rims are more or less parallel to the 80°E and 103°E longitude, respectively (Fig, 33)* The boundary of this region is essentially coincident with the —400 milli- gals contour line of the Bouguer gravity anomaly. This region represents one of the major Bouguer gravity lows in the world with the lowest value being —575 milligals at the center of this region. Three earthquakes which occurred at the eastern boundary (Fig. 33) are used where four distinct wave paths are sampled by nine surface wave trains of both Rayleigh and Love types (Table 24). Group velocities obtained from these wave paths are found to be unusually low as compared with available published data. A comparison was given in Figure 32 where group velocities of Rayleigh waves from paths 1 and 3 were plotted against the average dispersion curves given by Ewing, et al. (1957)* is immediately clear that the Rayleigh wave group velocity of the Tibetan 132 Fignre 33* Location and wave paths of the Tibetan platform. 133 134 100* l30‘ lot:1 1 0 0 ' 1 I0 ‘ Table 24. ¥ave-paths from which group velocities for Tibetan platform are obtained Patb Earth quakes Record ing Station Com ponent Dispersion Disturbance Period Range (second) Wave Type 1 June 15, 1971 CHG Z Rayleigh 2 August 30, 1967 LAH Z Rayleigh 3 Sept. 28, 1966 LAH Z 65-85 Rayleigh Sept. 28, 1966 LAH N-S 28-50 Love Feb. 5, 1966 LAH Z 25—4o Rayleigh 4 Sept. 28, 1966 NDX z Rayleigh Sept. 28, 1966 NDX N-S Love Feb. 5, 1966 NDX z 28-40 Rayleigh Feb. 5, 1966 NDX N-S 40-50 Love 135 platform is at least 10 percent lower than that of the con tinental average value and this difference persists to a period as long as 120 seconds. This latter period is particularly significant because it indicates a correspond ing depth below which the structural difference between the Tibetan platform and the average continent disappears. Since the period is about 60 seconds at which the con tinental and oceanic dispersion curves merge, the fact that the Tibetan dispersion curve merges into the normal con tinental dispersion curve at the period of 120 seconds indicates that the abnormal structure of the Tibetan plat form reach deeply into the upper mantle. Theoretical models which fit the observed Rayleigh wave data of paths 1 to 3 are given in Figures 34 to 36 and Tables 25 to 27. The quality of these fit are shown in Figure 37. It can be seen that not only the structures of the Tibetan platform are distinctly different from Guten berg model and Canadian shield found by Brune and Dorman (1963)9 but also considerable differences in velocities are present along various paths. Path 3 crosses the southern edge of the Tibetan platform (Fig. 33) and the resulting model T3 shows a four—step increase of shear velocity before the velocity reaches the maximum value of 4.5 km/sec at a depth of 55 km* A four—layered crustal model was proposed because four—layer is the lowest number of layers that gives satisfactory fitting. The first layer 136 Figure 3^* Resulting model of the Tibetan plat form for wave path 1 in Figure 33* 137 138 1.5 . 2.5 SHEAR VELOCITY , km/sec 3.0 3.5 4.0 4.5 ■■■ Tv Tibetan Platform G : Gutenberg C: Canadian Shield i • T , gH c r* i i r 40 60 -8 0 -100 -120 -140 J l6 0 E D E PTH Figure 35# Resulting model of tlie Tibetan plat form for wave path. 2 in Figure 33* 140 SHEAR VELOCITY , km/sec 1.5 , 2.5 ~T— * — 3.0 — I — 3.5 ■ET 4.0 -------- ,---------- 4.5 5.0 0 20 40 60 80 100 120 140 160 V Tibetan Platform G: Gutenberg C: Canadian Shield }— L------------1 ------------ L t “[ I I I I L _ -----1 Gr I ^ - 1 rm i r D E P TH Figure 36. Resulting model of tlie Tibetan plat form for wave path 3 in Figure 33* 141 SHEAR VELOCITY , km/sec 1,5 4 2,5 3.0 4.0 , - k . T3: Tibetan Platform G: Gutenberg C: Canadian Shield 't ~ l I i I i L _ T 3 — ^ 4.5 i - 1 r* i i . j r GrJ C 0 20 40 60 80 100 120 140 160 D EPTH Table 25# Tibetan platform model fit (l) (for wave path l) H(km) a (km/sec) 6(km/sec) P(e/cm3) 3 2.7 1.56 2.35 18 5.89 3.40 2.75 25 6.23 3.60 2.95 25 6.58 3.80 3.15 30 7.53 4.35 3.30 105 7.10 4.10 3.31 143 Table 26. Tibetan platform model Tit (2) (for wave path. 2) 1 1 ( km) ___ a(km/sec) 3(km/sec) o p i s /cm ) 14 5# 55 2. 80 2.70 14 5.60 3.18 2.90 25 6.40 3.30 3.00 25 6.60 3.80 3.15 35 7.90 4. 55 3.30 25 7.10 4.10 3.35 25 7.10 4.10 3.36 10 7.10 4.10 3.38 25 7.10 4.10 3.39 144 H(ki 2 18 25 25 20 20 10 25 10 10 25 25 Tibetan platform model fit (3) NDX September 28, 1966 (for wave path. 3) :m/sec ) 3(km/sec) p (&/cm 3.00 1.56 2.40 5.55 3.20 2.80 6.40 3.60 2.90 O O • 4.00 3.20 7.90 4.55 3.33 7.50 4.30 3.33 O H • 1> 4.10 3.30 O H • P- 4.10 3.36 7.17 4.10 3.37 O H • 4.10 3.38 O H • t- 4.10 3.39 O H • 4.10 3.41 145 Figure 37# Group velocities of representative wave paths of the Tibetan platform. 146 DQji E 3 & g • h J r ' I v i o d e l fit | i June 15, 1 971(1) J | J AH August 30, !9'"'?(2) i S NDI September 28, 1966(3) S JL f - / 0 > w .' O ^ /f'\ rra s ? i t s r > 1 * * * J M <1 with, shear velocity of 2.8 km/sec can be considered a sedi mentary layer which agrees with the report by Mu, et al. (1973) that thick sedimentary rocks were found in Mount Jolmo (Himalayas). The second and third layers with shear velocities of 3*2 and 3*6 km/sec fall into the velocity ranges of granitic and basaltic rocks (Steinhart and Meyer, 196l). However, laboratory measurements (Simmons, 1964) show a great variety of composition for these velocities. Therefore, velocities alone cannot determine uniquely the rock types. The fourth layer with shear velocity of 4.0 km/sec deserves special attention because this velocity is slightly higher than that for an average crustal material, and yet is not great enough to be mantle material (Stein— hart and Meyer, 1961). According to Simmon's laboratory results (1964), a crustal material of a shear wave velocity of 3*36 km/sec at a pressure of 1 bar can have a shear wave velocity of 3*94 km/sec at pressure of 10 kilobars. At the depth of 50—70 km, the pressure is approximately 20 kilobars, and hence the shear wave velocity increase be yond 4.0 km/sec is possible. Nevertheless, allowing the opposite effect of higher temperature at greater depth on the velocity, a crustal material with shear wave velocity of 4.0 km/sec at the depth of 50—70 km is feasible. In the upper mantle, shear wave velocities of this model are not only lower than those of Gutenberg model and of the Canadian shield, but the low-velocity zone is more 148 prominent as well. This may suggest a higher degree of partial melting in the upper mantle (Anderson, et al. , 1972), and imply either high temperatures or low melting point of materials in the upper mantle. Path 1 crosses the Tibetan platform in northwest- southeast direction (Fig. 33) » and results in the model T^ (Fig. 37). The entire path 2 is inside the Tibetan platform in a east—west direction, and crosses almost entirely through the areas with the lowest Bouguer gravities. This cor responds to a model T^ of even thicker crust of nearly 80 km. Less confidence, however, is placed on the result of this wave path than on the other two because of possible interference. It should be mentioned that the fitting for this path is poorer than those for the other two wave paths owing to the irregularities on the dispersion curve, which may suggest that there are more velocity variations than the resulting model implies. Comparing these three resulting models, it can be inferred that the crustal thickness increases gradually from the southern edge of the Tibetan platform to the center where the Bouguer gravity is the lowest. Similar gradations occur in the crustal velocities. Despite differences in crustal structures found along paths 1, 2 and 3* the upper mantle structures are all similar to one another with a low—velocity zone. 149 In the last column of Table 24, disturbances of the group velocity dispersions are indicated on four of the wave paths across the Tibetan platform. These disturbances were observed from the corresponding two-dimensional plots where energy distributions are not smoothly continuous. If we consider surface wave dispersion to be the result of the constructive interference through a regular velocity structure, then disturbance on the dispersion implies the irregularities on the structure. The structural irregulari ties occur in such a way that waves of certain periods were shifted into later arrivals. The dimension of the struc tural irregularities correspond to the wavelengths of the disturbed waves. Southeastern China This region is characterized by the high Bouguer gravity (ranges from O to —125 milligals) and much lower regional topographic relief than the Tibetan platform with north—south trending low mountains and small basins (Fig. l). It is bounded on the west side by the longitude 103°F and on the north side by the latitude 30°N. It extends to the Pacific Ocean on the south and east (Fig. 38). The western boundary, given by the —400 milligals Bouguer anomaly contour, is parallel to a north—south trending mountain belt. The northern boundary, as mentioned pre viously, coincides with the petrological contact between 150 Figure 38* Location and wave paths of* south eastern China. 151 Q- i n 152 Precarabrian metamorphic rocks and Holocene sedimentary rocks. Wave-paths from which group velocities were ob tained are shown in Figure 38 and Table 28. Seismograms and the two-dimensional plots are shown in Appendix V. Group velocities obtained from these wave—paths for the southeastern China are close to those of an average continental structure. Xn Figures 39 and 40, group velocities for this region and for Gutenberg model are plotted for comparison. They show an overall difference of less than 0.2 km/sec* Furthermore, the shapes of the two dispersion curve are very similar to each other, indicating that the structure of the southeastern China is very similar to that of the Gutenberg model with but slightly lower velocities. For this reason, Gutenberg model was taken as the starting model for the fitting process. Re sults of fitting are shown in Figure hX and Table 29* quality of the fitting is shown by the solid lines in Figures 39 and 40 (Love wave dispersions were first fitted to obtain the model fit of Figure 40, then compressional wave velocities were adjusted to fit the Rayleigh wave dis persions for the model fit in Figure 39). As expected, the resulting model for the southeastern China is similar to the Gutenberg model except with lower shear velocities in the crust and in the upper mantle. Observed group velocities are deduced from wave paths that cover a narrow belt across the entire south- 153 Table 28. Wave paths from which, group velocities for southeastern China are obtained Path Earthquake Recording station Component Dispersion disturbance (periods) 1 Feb. 5, 1966 ANP N-S Feb. 5, 1966 ANP Z 33-39 sec 2 Feb. 13, 1966 ANP z Feb. 13, 1966 ANP N-S 154 Figure 39* Rayleigh, wave group velocities ob tained from multiple filtering for southeastern China. ANP FEBRUARY 5,1966 ANP FEBRUARY 13, 1966 MODEL FIT GUTENBERG MODEL Figure 40. Love wave group velocities obtained from multiple filtering for south eastern China. 157 GROUP VELOCITY (km/sec) 4.4 4.0 3.6 3.2 0 ' 20 4 0 60 8 0 100 120 PERIOD (sec) LOVE WAVE DISPERSION .99 o Gutenberg Result of N-S comp ANP Feb. 5,1966 Model fit H C J i 00 Figure 4l. Resulting model of southeastern China, 160 1.5 . 2.5 t— r SHEAR VELOCITY , km/sec SE: G: C: Southeast C hina Gutenberg Canadian Shield 3.5 4.0 - k . i~i i i i i S E 4.5 r r 1 5.0 0 20 40 60 80 -120 140 160 D E PTH Table 29. Southeastern China model fit (for both Love and Rayleigh wave) H(km) a(km/sec) 3(km/sec) P (e/cm3) 2 O O • 2.90 3.00 IO 5.00 O H • 3.05 25 6.00 3.55 3.20 12 8. 10 4.65 3.32 25 8.05 4.55 3.34 25 7.80 4.15 3.37 25 O 00 • 4.15 3.38 15 7.90 4.40 3.39 25 7.90 4.40 3.41 25 7.90 4.40 3.42 161 eastern China region (Fig. 38). Strictly, the foregoing results represent merely the structure along the wave paths. Nevertheless, from the small difference in the observed velocities of ANP February 5* 19^6 and ANP Febru ary 13 9 1966 and small variation in the topography, it may be inferred that the structural variations are not signi ficant within southeastern China as compared with the Tibetan platform. So that, the resulting crustal and upper mantle structure may still give an adequate repre sentation of the entire region. Northeastern China Physiographically, this region is essentially a basin surrounded by mountain belts on both east and west sides. It is bounded on the south by the latitude 31°N and extends to the border of China on the east and north (Fig. 42). The western boundary, which was drawn on the —70 milligals Bouguer anomaly contour, coincides with petrological contact between Precambrian metamorphic rocks and Holocene sedimentary rocks. Wave-paths from which pure-path group velocities deduced for this region are shown in Figure 12 and Tables 9 to 12. Pure—path group velocities deduced from the com posite wave—paths using regionalization are slightly great er than that of Gutenberg model for the periods shorter than 35 seconds, and slightly less in the period—range of 16 2 Fifpjire 42. Location and wave paths of north eastern China. 16 3 164 35 to 95 seconds. For the periods longer than 95 seconds, group velocities of this region are greater than that of the Gutenberg model (Fig, ^3)« This dispersion corresponds to a structure of a thinner crust, deeper and less pro minent low-velocity layer in the upper mantle than that of the Gutenberg model (Fig, hh and Table 30)• Petrologic and topographic changes are shown within this area north of the latitude 40°N (Fig, 25 and l), Pos sible lateral variations are, therefore, conceivable to exist. However, from Rayleigh wave phase velocity study, Tseng and Sung (1963) have concluded that the crustal thickness in at least the south portion of this region is quite uniform, except perhaps in region along the Yantze river basin. Yet the crustal thickness from the present group velocity analysis is about 31 km, which is appre ciably thinner than that derived from phase velocity data (see Fig, 4). Central China This region is characterized by predominently north—south trend mountain belts with basins on the north west, It is defined on the north side by the border between China and Mongolia, and on the east side by the —70 milli— gals Bouguer anomaly contour (Fig, 6) where Precambrian metamorphic roclcs are in contact with Holocene sedimentary rocks (Fig, 25). It extends south to the latitude of 31°N 165 Figure 43# Rayleigh, wave group velocities ob tained from multiple filtering of northeastern China. 16 6 167 RAYLEIGH WAVE PERSiON Vi \ . r ' ^ ^ ^ •«-w . . • * ! V I < / - ” 5 * . ? ru | O i v. ; s , i - i i • • • • i1 - L* ■ 5 . - ! > —> .lwVj r\ \ >v a 0 j AV/ 0 A 0 PATH 1 PATH % f MODEL FIT • GUTENBERG MODEL © iuL-‘ 7 u , 0 - . %*u, i ' i t 'ie J ? 1 (S8S) « J f « > P ! » a ^ Figure kk0 Resulting model of* north-eastern China. SHEAR VELOCITY , km/sec 1.5 , 2.5 £ 3.0 3.5 4.0 --■U, l~i i i JL_ I L _ N E: Northeastern China G: Gutenberg C: Canadian Shield I 1 M II ne| 4.5 Gr i ^ A J r~ i i . j r c 5.0 0 20 40 60 80 100 120 140 160 D E PTH Table 30* Northeastern China model f*it H(km) a(km/sec) { 3 (km/sec) p ( g/cm3J_ 1 3.00 1.50 2*75 5 5.55 3.30 3.00 23 6.50 3.60 3.10 23 8.05 4.42 3.33 10 8.02 4.21 3.34 10 7.90 4.20 3.35 10 7.90 4.20 3.36 10 7.95 4.30 3.37 30 8.00 4.32 3.38 20 8.00 4.35 3.39 23 8.05 4.40 3.40 170 where Pleitocene sediments are in contact with Precambrian metamorphic rocks and Paleozoic igneous rocks* The western boundary, mainly defined on the basis that group velocities observed for this region are different from areas on the west, was drawn along the longitude 98°E. Wave—paths from which pure-path group velocities are deduced for this region are shown in Figure 43 and Tables 13 to l6. Group velocities from different wave — paths (Fig. ^3, paths 1, 2, and 3) are somewhat different from one another. Those obtained from path 3 (Table 13) are appreciably lower than that obtained from the other two paths in the periods less than 30 seconds. For this reason, group velocities from path 3 were fitted into a separate model. Despite minor differences in group velocity values between paths 1 and 2, common features can be observed from Tables l4 and l6. Group velocities in crease considerably from periods of about 23 to 30 seconds, and then decrease slightly at a period about 40 seconds. Xn Figure 46, group velocities of this region are compared to the Gutenberg model. The corresponding structures obtained from model fitting are shown in Figures 47, 48 and Tables 31 and 32. For the model fitting of paths 1 and 2, it shows a crust of about 38 km thick with shear velocities slightly lower than that of the Gutenberg model in the upper mantle. However, the resulting model for the path 3 shows a crust of about 48 km with lower 171 Figure ^5# Location and wave paths of Central China. 172 Figure 46. Rayleigh wave group velocities ob tained from multiple filtering of central China. 174 1/ MODEL FIT A PATH 1 0 PATH 2 □ PATH 3 # Gutenberg model Fif^ure - i 7 • Resulting model of central Cliina (path 3), 176 177 1.5 . I — { 2.5 SHEAR VELOCITY , km/sec 3.0 3.5 4.0 4.5 C C : Central C hina G: Gutenberg C: Canadian Shield 1~I I i I i L _ I Lj i r~ R _ _L r 5.0 0 20 40 60 80 100 120 140 160 D E PTH Figure ■ > 4 8. Resulting model of central China ( pa th P. 178 179 1.5 . 2.5 ■* SHEAR VELOCITY , km/sec 3.0 3.5 4.0 4.5 0 20 40 C C . Central C hina G: Gutenberg C: Canadian Shield ■ tH ------------ 1 -------- T i-i i i C C I J. r r V GrJ C 80 100 120 140 160 D EPTH Table 31* Central China model Tit (patb 3) H(ltm) a (km/sec) 3(km/sec) O (g/cm ) 29 6.14 3.20 2.74 19 6.58 3.60 3.00 12 8.20 4.55 3.32 10 8.17 4.52 3.34 10 8.14 4.47 3.35 10 8.10 4.51 3.36 10 8.07 4.46 3.37 25 8.02 4.41 00 CA • CA 25 7.93 4.37 3.39 25 1A 00 • 4.35 3.41 25 7.89 4.36 3.43 25 7.98 4.38 3.46 25 8.10 4.42 U • ■ F - 00 25 8.21 4.46 3.50 180 km 19 19 12 10 10 25 25 25 25 25 25 25 25 Central China model fit (path l) a_ . . ( W sec) 6. 14 6. 58 7.60 7.60 7.60 8.10 8.07 8.02 7.93 7.85 7.89 7.98 8.10 g(km/sec) 3.20 3.80 4.40 4.40 4.40 4.20 4.20 4.41 4.37 4.35 4.36 4.38 4.42 P (g/cm 2.74 3.00 3.32 3.34 3.35 3.36 3.37 3.38 3.39 3.41 3.43 3.46 3.48 181 velocities in the second layer, This discrepancy could have come from the following- sources: (l) since paths 1 and 2 are nearly north—south and path 3 is nearly east- west, differences in group velocities could be contributed from structural inhomogeneities along these directions, (2) errors in estimating the path-length percentage in the regionalization, (3) direction—dependent boundary effects in this region, and (4) interference with other modes* Nevertheless, if structural inhomogeneities play a part, they should be restricted to a narrow east-west zone in order not to affect group velocities of paths 1 and 2, and incorrect path length percentage cannot be important be cause group velocities of the composite wave path 3 are low. Therefore, interference with other modes and the boundary effect along the Tibetan platform where Bouguer anomalies have steep gradient were most likely to be re sponsible for the lower group velocities of path 3* Judg ing from the values of the Bouguer anomaly of this region, results of paths 1 and 2 are appropriate to represent the structure of this region as they are discussed in the interpretation section. Northwestern China This region is characterized by the east—west trend of alternating mountains and basins with low Bouguer gravities in the mountainous areas. It is defined on the 182 south, by the — 400 milligals Bouguer anomaly contour, which is parallel to an east—west trending mountain belt (Fig. *+9). Wave paths from which pure—path group velocities are deduced are shown in Figure 49 and Tables 17 to 19. Group velocities obtained for this region are plotted in Figure 50 with that of Gutenberg*s for comparison. Group velocity curve of this region is almost parallel to that of Gutenberg*s. Values of group velocities are on the average about .35 km/sec lower than those of Gutenberg*s. They are also considerably lower than those of central China. This is why a regional boundary must be drawn be tween this region and central China even without other criteria. It is drawn along the places at which Bouguer gravities are higher than the surrounding areas. Because wave path 2 (Fig, 49) crosses only a small portion of this region, group velocities from which were not used to deduce the structure. Result of model fitting is shown in Figure 51 and Table 33* It shows an average crustal thickness of about 45 km, and a comparable upper mantle structure with that of the Tibetan platform. It should be emphasized that, as would be explained in the later section, the variations of Bouguer anomalies and changes in elevations correspond to diverse crustal thicknesses and upper mantle structure. According to 183 Figure 49 Location and wave paths of north western China* 184 © _ o 185 Figure 50. Rayleigh wave group velocities ob tained from multiple filtering of northwestern China. 186 RAYLEIGH WAVE DISPERSION A A PATH 1 IN FIGURE 49 MODEL FIT G u te n b e r g m o d e l 1 0 0 1 5 0 PERIOD (sec) Figure 51# Resulting model of northwestern China# 189 SHEAR VELOCITY , km/sec 2.5 ~T~T 3.0 3.5 4.0 4.5 I I NW : Northwestern C hina G: Gutenberg C: Canadian Shield N W r. \ r r1 GrJ C 5.0 0 20 40 60 80 100 120 140 160 D E P TH Table 33. Northwestern China model fit H(km) a (1cm/sec) 3(km/sec) o p (s/cm ) 5.0 4.16 2.60 2.74 20.0 6.4o 3.20 3.00 20.0 6.60 3.60 3.28 o • o H 7.80 4.35 3.32 30.0 7.80 4.35 3.33 o • o H 7.10 4.10 3.35 25.0 7.10 4.10 3.3 6 10.0 7.10 4.10 3.37 o • o H 7.10 4.10 3.38 25.0 7.10 4.10 3.39 25.0 7.10 4.10 3.41 25.0 7.55 4.3 6 3.43 190 F i g u r e 579 crustal thickness of* this region ranges from 38 km in areas with Bouguer anomaly of —100 milligals, and 47 km in areas with Bouguer anomaly of —200 milligals, Mongolia This region is more complex than all the other re gions described in the preceding sections. It is characterized by an east-west trend mountain belt in the southwest, basins in the east, and a north—south trend mountain belt in the north. It is mainly enclosed by the international borders of Mongolia to China and Russia ex cept on the southwest side by the change of geology from predominently faulted basic and ultrabasic rocks of this region to predominently sedimentary rocks in the north western China areas (Fig, 52). Wave—paths from which group velocities deduced are shown in Figure 52 and Tables 20 to 23* Pure-path group velocities deduced from paths 1, 2, and 3 are appreciably different from each other as can be observed from the plot of Figure 53* Group velocities from path 1 are so low that they are even lower than those of the Tibetan plat form in the periods shorter than 70 seconds. On the other hand, group velocities from paths 2 and 3 are much greater and similar to each other in the same period range, but become divergent to each other in the longer periods where group velocities of path 3 match with those of path 1. This 191 Fij^iire 52. Location and wave paths of Mongolia, 192 193 Jane* Figure 52 Figure 53* Rayleigh wave group velocities ob tained from multiple filtering for Mongolia. 194 195 Figure 53 y MODEL FIT / m o d e l f i t A PATH 1 ( Ml ) □ PATH I (M2 ) O PATH 3 (M3) divergence in group velocities indicates that considerable inhoraogeneities are present in the areas of Mongolia, not only in the crustal conditions but also in the upper mantle• Results of model fitting are shown in Figures 54 to 56, and Tables 34 to 36, The fitted models show that group velocities of path 3 correspond to a structure with the crustal thickness of about 30 km, path 2 correspond to similar crustal thickness with more prominent low-velocity zone in the upper mantle, and path 1 corresponds to a crust of about 60 km thick. Xt is worthy to note that pure—path group velocities deduced from different wave paths are different, which corresponds to a difference on the crustal thickness to as much as 25 km. The wave path 1 from which lower group velocities are derived crosses the same boundary (-400 milligals boundary) at small angles of the Tibetan platform as wave path 3 of central China. Multiple reflections off the structural (tectonic) boundary produce the later arrivals, and therefore lower group velocities result. This leads to the conclusion that lower group velocities are results of boundary ef fects, not structural. For this reason, the crustal thickness of Mongolia is considered to be about 32 km in general with local thickening to about 55 km in areas where Bouguer anomalies reach —300 milligals. 196 Resulting; model of Mongolia path 1 / > r -j \ 197 SHEAR VELOCITY , km/sec 1.5 , 2.5 3.0 3.5 4.0 4.5 Ml: M ongolia G : Gutenberg C: Canadian Shield - k - ’ 1 i i i I i L — Ml GrJ i - A r' i i r r* 5.0 0 20 40 60 80 -100 -120 140 160 D E PTH Figure 55* Resulting model of Mongolia, path. 2 (M2). 199 1.5 , 2.5 -f--i— * ■ SHEAR VELOCITY , km/sec 3.0 M2 : Mongolia G: Gutenberg C: Canadian Shield 3.5 4.0 T 4.5 T“ j i i i L - M 2 r' i i .j r GrJ C 5.0 0 20 40 60 80 100 120 140 160 E O O < N 1 DEPTH Figure 5o# .Resulting model of Mongolia path. to). 201 202 SHEAR VELOCITY , km/sec 1.5 . 2.5 3.0 3.5 4.0 5.0 0 20 40 60 80 100 120 140 160 M 3: " G: Gutenberg C: Canadian Shield --U- ■ n i • M 3 Gr i r- i i . - j r r1 Figure 56 D E P TH 06 Table 34. Mongolia model Tit Tor Path 1 (Ml) H(km) a (km/sec) 3(km/sec) P (g/cm5) 18 6.40 3.20 3.00 22 6.50 3.30 3.10 20 6.60 3.55 3.28 io 7.80 4.30 3.32 30 7.80 4.30 3.33 10 7.80 4.30 3.35 25 7.40 4.20 3.36 20 7.40 4.10 3.37 25 7.80 4.30 3.39 25 7.80 4.30 3.41 y 203 Table 35. Mongolia model f*±t for Path 2 (M2) H(lcm) a (km/sec) 3 (km/sec) p (s/cm3) 1.0 4.16 2.60 2.74 O • m H 6 • 4o 3.00 3.00 O • m H 6. 6o 3.40 3.28 10.0 7.80 4.35 3.32 o • o 7.80 4.35 3.33 o • o H 7.10 4.10 3.35 o • m CM 7.10 4.10 3.36 o • o H 7.10 4.10 3.37 O • o H 7.10 4.10 3.38 25.0 7.10 o H • — 3.39 25.0 7.10 4.10 3.41 25.0 7.55 4.36 3.43 25.0 7.60 4.38 3.46 25.0 8.10 4.42 3.48 204 H( k: 2 8 20 10 30 10 25 10 10 25 25 Mongolia model fit for Path 3 (M3) a (km/sec) 6.40 6.40 6. 6o 7.40 7.50 7.50 7.40 7.40 7.40 7.40 7.40 g (k m / s e c ) 3.20 3.20 3.55 4.30 4.30 4.30 4.20 4.10 4.10 4.30 4.30 p 3.00 3.10 3.28 3.32 3.33 3.35 3.36 3.37 3.38 3.39 3.41 205 INTERPRETATIONS Correlations From tlie present surface wave dispersion study, it was shown that group velocities obtained from various regions in China and Mongolia are different, which cor responds to dissimilar crustal thicknesses and upper mantle velocities. Although, the present data are far from sufficient to provide a complete structural picture, they do reveal regional characteristics. More importantly, those regional characteristics were found to correlate with several other geophysical and geological findings. These are: 1. Crustal thicknesses and the Bouguer anomaly: Comparing structures in each region described in the pre ceding sections with the regional Bouguer anomalies (Fig. 6), it is found that there is a consistent trend that thicker crust corresponds to lower Bouguer anomalies (Table 37 and Fig. 57)* The correlation between the crustal thicknesses and Bouguer anomalies in China and Mongolia are fitted into two straight lines with different slopes and the same intercept crustal thickness at the zero Bouguer anomaly. 206 Table 37* Correlation between crustal thickness and Bouguer anomaly Region Crustal Thickness (km) Bouguer Anomaly (milli^rals) Tibetan platform 76 -550 Southeastern China 37 - 50 Northeastern China 30 - 20 Central China ko -150 Northwestern China ^5 -200 Mongolia (l) 60 -175 (2) 35 -100 207 Figure 57* Correlation between the crustal thickness and the Bouguer anomaly. 208 Crustal Thickness (km) 80- eastern /China western China, and Mongolia -600 -500 -400 -300 0 Bouguer Anomalies (milligals) to o CO Figure 57 Tseng (197^0 noted that if the gravity compensation is achieved mainly in the upper mantle, then the Moho depths would tend to be equal* The wide variation of Moho depths, however, suggests that this is not true, and the major compensation is probably accomplished within the crust* He postulated this on the basis of linear cor relations between the crustal thickness and the topographic elevation in eastern China* Tseng*s hypothesis is supported by our results of linear correlations between crustal thicknesses and Bouguer anomalies* To demonstrate this connection, let us assume that this is true; then if p^ represents the average crustal density of region A with crustal thickness y, and a reference region of average crustal density p with crustal thickness yQ for which the Bouguer anomaly is zero (Fig. 58), then we have the following relation: BA(Bouguer anomaly) = - theoretical where G. , , is the adjusted observation value* Xf we Adob assume infinite homogeneous slabs for the structures of both region A and the reference region, then the Bouguer anomaly of region A can be expressed in a form similar to the Bouguer correction: Figure 58. Relation of Moho depths of region A and the reference region. Region A reference region in which. Bouguer anomaly is zero t P y a A________ Po Moho — — y sea level I Moho y-yo Pm 212 in which. m is the density for upper mantle, and is mass-Bouguer—gravity conversion constant. This result shows that if* the gravity compensation is achieved above the Moho discontinuity, linear correla tion between the crustal thickness and the Bouguer anomaly is a necessary consequence. Inasmuch as the present data show linear correlation between the crustal thickness and the Bouguer anomaly within the areas of western China and Mongolia, and areas of eastern China (Fig. 57), we believe that the gravity compensation is achieved above the Moho discontinuity within each of these two large regions. It should be emphasized, how ever, that since the correlations are fitted into two straight lines instead of one, the gravity compensation is not entirely achieved above Moho within the areas of China and Mongolia as a whole. This can be readily ex plained if we write similar equations for eastern China, and for western China and Mongolia individually: The density contrasts between the crust and the upper mantle, as shown by the slopes of straight lines in Figure 57 $ are different for eastern China and for western China for eastern China 2ir(p -p )GC -BA + ( V ° o ) y for western China and Mongolia o m w 213 and Mongolia* Since on P - j —. > P E w we may conclude that the average crustal density of* western China and Mongolia is smaller than that of eastern China* Nevertheless, the intercept thickness at zero Bouguer anomaly for both eastern and western China and Mongolia are equal to 27 km (Fig. 57)* implying that (P -P ) (p -p ) m o _ m o (p -P ) y0 (D -p ) yo m E m w but this requires p - p = p - p or p = p m E m w E w which contradicts to what was just concluded. Therefore, the only other alternative is to put different mantle densities for each of these regions. Xn other words, we need to rederive a relation that can be applied to both these regions. Referring to Figure 59* let us assume infinite flat slab again and different mantle densities above the depth of compensation for eastern China, western China and Mongolia, and the reference region as p , p , and p . Following the same calculations as me * mw mo before, we have: BA = 2nGC{[p y + (Y -y )p ] - [y P + (Y -y )p ]} E E o E m E o o o o mo for eastern China and similarly BA = 2ttGC{[p y + (Y -y )p 1 - [y p + (Y. -y )p ] } w w o w m w o o o o mo 214 Figure 59* Simplified density model for eastern China, western China and Mongolia, and the reference regions. 215 western China and Mongolia w Moho mw w reference region Moho mo mo Eastern China y E P T?. Moho mE Depth of compensation sea level o 216 for* western China and Mongolia. Rearrange the terms, we have ______B A_______ ^mo^mE * (Po"Pm o ) ( . Ye = 2TTGC<pE -pm E > + ° (pE - > W y° (pE -pm E ) 1 J -D A (P -P ) (P -P ) B A „ mo m w o mo /ir>\ y = A n +Y —------- - — + y ------- : v!9) w 2ttGC-(p -P ) o (p -p ) o (p -p ) w m w w m w w m w by substituting = yQ + Ymo> (l8) and (19) become ^ A (P -P „) (P -P „) _____B A______ mo m E o m E / ^ ^ = 2nGC(PE -pm E) ym° (pE-pm E ) Y° (pE-pm E ) T, A (P -P ) (P -p ) B A mo m w o m w (oi \ V = + V---------- ; - + v ------------ V / w 2ttGC(p -p ) mo (P -p ) o (p -p ) w m w w m w w m w From these two equations, we can obtain a similar result as (5): p - p <P -p (22) m E E m w w From the same intercept thickness at the zero Bouguer anomaly for eastern and western China and Mongolia, we have the following relation: (Pmo-pm E ) (po-pm E} _ ^mo^mvP (pQ-pm w ) , x Ymo (p - p ) + yo (p -p ) ymo (p -p ) + Yo (p -p ) E m E E m E w m w w m w Before we discuss the implications of (23) about the densities in the upper mantle, let us digress to examine the general nature of p o , p mQ, oE» P w» P mg mw! 217 since the Bouguer anomaly in most oceanic areas is close to zero, we may consider oceanic areas as the reference region* The crustal thickness of oceanic areas in general ranges from 5 to 10 km with about 5 km water. If we take the average density of oceanic materials as 2.9* then the average density of the oceanic crust would be: _ 2. 9- 10 + 1.1 x 5 ___ p ----- rr------- = 2. 23 o 15 This is certainly much smaller than the average density of continental crust (granite 2.5—2.8, gabbro 2.8-3*l)* Therefore, the average crustal density of ocean (theoreti cal) is less than that of eastern and western China, i.e., p < p an d p <p (24) o E o w For a low average crustal density in the oceanic area, its average upper mantle density must be higher in order to make up for the zero Bouguer anomaly. That is, ^mo V e ^mo *rnw (25) From these considerations, the second term in (20) and (2l) would be negative and the third term would be positive and greater than yQ# In order to hold the equality (23)* one of the fol lowing must be true: 218 Case (a) P -P „ P -P mo m E mo m w (2 6) ^E *~mE ^mw p -p p -p o m E o m w p -P p -p E m E w m w (27) (b) p -P „ P -P 1X10 m E > mo m w (28) p -p p -P E m E w m w P -P „ P -P o m E < o m w (29) p -p__ p -p E m E w m w (c) p -p p -P mo m E ^ mo m w ('30') Ptr"P rp P -P E m E w m w p -p _ P -P o m E ^ o m w > u,. . ^ w ( J p -P p -p E m E w m w i): if (a) is true Prom (22) and (2 6) or p -P | < |P -P mo m E mo m w PmE ^ m w 219 but from (22) and (27) > - 0 m w o or m w which is a contradiction, therefore it cannot be true. Case (ii): if (b) is true From (22) and (28) this is again conflicting. Therefore, the only choice is that (c) is true; from (22), (30) and (31)* for (c) to be true, the average mantle density of eastern China has to be greater than that of western China and Mongolia, That is, or ^ m E ^ m w but from (22) and (29) or m w (32) 2 2 0 This is very interesting and useful results because from the lower values of the Bouguer anomaly of western Cliina and Mongolia comparing with that of eastern China, lower average densities are expected. But, Bouguer anomalies alone fail to discriminate whether the de ficiency in mass occurs in the crust only, or in the mantle only, or occurs both in the crust and in the mantle. From (22) and (32) we may conclude that low Bouguer anomalies in western China and Mongolia are a result of lower densities both in the crust and upper mantle as com pared with eastern China in such a way: p - p < p - p m E E m w w In the present study, correlation between the crustal thickness and the Bouguer anomaly can be used to infer crustal variations from regional Bouguer anomalies where no observed group velocities are available. Re sults of the crustal variations in each region from the correlation are summarized in Table 38. 2. Low-velocity zone in the upper mantle and the seismicity: differences in the depths and velocities of the low-velocity zone in the upper mantle were seen among the six regions from the present results of China and Mongolia. Low-velocity zone has been interpreted as a result of partial melting (Anderson, et al., 1972). Therefore, prominent low-velocity zone (upper mantle shear 221 Table 38* Variations in crustal thickness in each region obtained from correlation of re gional Bouguer anomalies Region Range of Bouguer anomalies (milli^als) Range of Crustal thicknesses ( km) Tibetan platform -400 to -375 63 - 78 Southeastern China O to -125 25 - 38 Northeastern China 0 to - 60 10 - 25 Central China - 90 to -200 35 - ^5 Northwestern China -125 to -4oo 38 - 63 Mongolia -125 to -350 38 - 58 222 velocity less than 4.15 km/sec) suggests a higher percent age of partial melting. The consequence of this is the reduction of resistance for relative movement. Hence, the major movement between the lithosphere and the astlieno- sphere is believed to occur within the low-velocity zone. Consequently, regions with a prominent low-velocity zone are more mobile than regions that do not have a prominent low-velocity zone. For this reason, they are defined as mobile regions and stable regions respectively in this study. Distribution of this division in China and Mongolia is shown in Figure 60 and on Table 39- When the mobile regions interact with the stable regions, because of differential mobility, stresses are likely to ac cumulate along and near the boundary of the mobile re gions. This is the source of earthquakes. In Figure 60, it is seen that this is indeed the case; earthquakes cor relate with the mobile regions, especially deep earth quakes . 3. Dispersion disturbance due to regional boundaries: As mentioned previously, disturbances of group velocity dispersion appear on several of the two- dimensional plots. It is noteworthy that these disturbed dispersions all occur along the wave paths across the Tibetan platform (Fig. 6l). This could imply that the structural changes across these boundaries are more pro minent around the Tibetan platform than any other regions. 223 Figure 60. Correlation between mobile regions and earthquakes. h: focal depth, M: mobile region, S: stable region. (Time period from 1500 to 1973 > after Shi, et aJL. , 1973* Scientia Geologica Sinica, No. 4.) 224 h> 300 -h< 20 0 * ' v . < < . m . . - ' • V -Jt^o * - L S N L ’ > W ' & h A k i Z f l ? ' u v * y r« C7 1500 2 - S 1000 500 0 .x ' h<35 • 35<K<50 4 70<H*;100 a 200<h<300 //r f * 50<h<70 Al00<h<200 ■ h>300 4 Z& Figure 60 225 Table 39* Classification of mobile and stable regions in China and Mongolia Region Classification Tibetan platform Mobile South-eastern China Stable Northeastern China Stable Central China Stable Northwestern China Mobile Mongolia Mobile 22 6 Figure 61. Disturbance of* the group velocity dis persions . Disturbance occurs in periods up to 40 seconds. Disturbance occurs in periods up to 65 seconds. 227 228 J , JAPAN «*»• u if?, EO ELLOW SEA EAST C H I N A S E A i ANP O S JHONGKC 0 W W S S N • EPiCEN TIER O H O W HKC S O U T H CHINA S E A B A Y or B E N G A ^ . 80 9 0 100° Figure 61 NO 120 This correlates with, the distribution of* the subduetive fault zones defined by the Chinese Academy of Sciences (197^0 and shown on Figure 2 in this report. Tectonic Implications We have seen in the areas of China and Mongolia that not only the crustal structures change from region to region, but the upper mantle structures as well. Further more, it was shown in the foregoing section that the variations in structures are correlative to other regional characteristics, such as Bouguer anomaly, seismicity, and the deep fault zones. The linear correlation between the crustal thickness and the Bouguer anomaly indicates a uniform density con trast between the crust and the upper mantle, and that the gravity compensation is achieved above the Moho Discon tinuity for the areas with the same slopes (Fig. 57)* Different slopes and the same intercept thickness at the zero Bouguer anomaly of the areas of eastern China and western China indicate differences not only in the crust— mantle density contrast, but also in the mantle densities, which implies that the structural differences extend into the mantle. Correlation between the seismicity and upper mantle structures indicates that stresses are accumulating un evenly within the earth's interior as a result of 229 structural inhomogeneity. Hence, tine wide structural variations may reveal either the potential for future earthquakes and tectonic movements, or they are a result of the tectonic history. Both these correlations suggest the close relation ships between the tectonics and crustal/upper mantle structures. Correlation between the regional boundaries and the deep fault zones, however, unveil explicitly the intimate associations of the tectonics and structures, Xn consequence, we may assume that the variety of crustal and upper mantle structures in the different regions of China and Mongolia has resulted from distinct tectonic events. Then the question arises, what types of tectonics could produce such a structural variation in these regions? Evidenced by the presence of the ophiolite suite in the Himalayas (Chang and Zeng, 1973)» and north—south trending compressive stresses in the western China (Molnar, et al., 1973)* the underthrusting of India into Eurasia generally has been accepted. Based on several belts of ophiolite suites in the Tibetan platform, Chang and Zeng (1973) suggested several stages of subduction in that re gion (Fig, 6 2 ), The consequence of those subduction events are the exceptionally low Bouguer anomalies (—575 milligals, Fig, 6), the extremely thick crust as shown by the present surface wave data, and lower densities of the upper mantle by the linear correlation between the Bouguer 230 Figure 62* Subduction of plates in the Tibetan platform given by Chang and Zeng (1973). 231 ALTKUN SHEN TUNKULA SHEN HIMALAYA SHEN KUNLUN SHEN GUNDIS SHEN 10-20 M(Y) 344-554 M(Y) 240-280 M(Y) 107-210 M(Y) 30-79 M(Y) M0H0 SURFACE N) OJ t ' O SEDIMENTARY LAYERS ■ ^ z x Z Z Z INTERMEDIATE IGNEOUS I j MOLASSE ] CONTINENTAL CRUST LITHOSPHERE | / 1 SERPENTINITE ROCKS 771 g r a n it e FLYSCH I INDIAN PLATE II SOUTH SI - SANG PLATE III NORTH SI - SANG PLATE IV CH1EN TUN PLATE V TSAIDAM PLATE Figure 62 anomaly and the crustal thickness. These consequences can be explained easily: when two continents collide under compressive pressure, because of the similar densities, the slab would be lifted up instead of sinking into the mantle. The result would not only thicken the crust but also reduce the average mantle densities. In addition, isostatic adjustment would tend to push away the mantle materials in compensating the overlapping of the slabs. Therefore, lower Bouguer anomalies are produced. To establish the close association of the subduction with low Bouguer anomaly and thick crust in a more general fashion, Bouguer anomalies of the entire earth (given by Woollard, 1972) were reviewed. Strikingly, it was found that for nearly all of the continents, Bouguer anomalies most com monly range from —20 to —160 milligals. Exceptions occur in the western portions of north and south America where the Bouguer anomaly reaches a low value of about -250 milligals. In north America, the low Bouguer anomalies are associated with the subduction of the Farallon plate (Atwater, 1970), and in south America low Bouguer anomalies are associated with the subduction of the east Pacific plate. Furthermore, in both these regions thick crust has been reported (Woollard, 1972). From these evidences, we may conclude that the subducting of lower density crustal material into the mantle not only in creases the crustal thickness, but also causes greater mass deficiency in the earth's upper mantle. With, these relationships in mind and then by ex amination of* the Bouguer anomaly distribution in mainland China and Mongolia, one can further infer that there may have been several subduction zones in western China and Mongolia (Fig. 6). Xf we assume that regions with the Bouguer anomaly lower than —2 50 milligals are areas where crustal subduction has occurred, then three subduction re gions can be identified in western China and Mongolia (Fig. 63)* One is associated with the Tibetan platform, the second is associated with northwestern China north of the Tarim platform, and the last is in the western part of Mongolia. This means that there may be at least three ancient plates, each marked by the Bouguer anomaly low trending east—west in the western China areas, and turning to a nearly north—south trend in Mongolia. Bouguer anomaly alone is not sufficient to confirm this inference. Several lines of evidence can further be cited: 1. A Silurian ophiolite suite (Zonenshain, 1973) has been reported in Mongolia and the Tarim platform (re fer to Fig. 25)• It strikes northwest-southeast in western China and are located more or less coincident with the international boundary between China and Mongolia. On this basis, Zonenshain (1973) concluded that there was an ancient ocean at the southern rim of Mongolia. 234 Figure 63 Distribution of subduction zones in China and Mongolia (shaded areas) 235 to C O o ^OUGUER / \ M r t , . . 9o° by the us a ,xf ^ean B^n?repaned and ,n^ ™ ^ c ^ s u -;cA4%aSm*« Figure 63 2. Earthquakes deeper than 200 km were reported in the Tien-Shan regions (Shi, et al., 1973; Fig* 60) . Deep earthquakes usually are associated with subduction zones. In addition, Molnar, et al. (1973) noted that the com pressive stresses trend northeast—southwest in these re gions which is perpendicular to the trend of Bouguer anomaly. From the correlation between the crustal thick ness and the Bouguer anomaly, the structural change occurs in a northwest—southeast trend which is in agree ment with the direction of stress. All the preceding results suggest that crustal and upper mantle structure in China and Mongolia may be de rived from tectonics related to multiple subductions. The subduction process, occurred earliest in Mongolia in the Paleozoic time, is progressively younger to the west and south, and the youngest is at the Himalayas in the Miocene time. It appears that subduction in the eastern part of Mongolia is underthrusting toward the west because of the northward convacity of the ancient ocean in Mongolia (Zonenshain, 1973)* Although there are deep fault zones in eastern China, owing to their present lack of seismic activity, they have been classified into an earlier tectonic cycle (Chinese Academy of Sciences, 197^0 • Furthermore, as suggested by Shi, et al. (l973)» stresses accumulated by the westward 237 movement of the Pacific plate are released in the oceanic areas east to China, consequently east China itself is more stable at the present tectonic cycle. 238 CONCLUSIONS By using the multiple—111ter technique, group velocities for various regions of China and Mongolia are obtained, and the major findings concerning the nature of the numerical filter and the resulting structures are: 1. In order to avoid severe interference between the fundamental mode surface waves and later arrivals, the parameter in the Gaussian filter must vary linearly with frequency• 2. Group velocities obtained from wave paths across the Tibetan platform are low in the period range of 10 to 120 seconds which corresponds to an unusually thick crust of approximately 78 km at the thickest part and to lower shear velocities in the upper mantle. Considerable lateral variations are present in this region. 3. Group velocities in southeastern China are close to an average continental structure with a crustal thick ness of about 38 km. 4. Group velocities of wave paths crossing all of southern China are about equivalent to values calculated by the path—length weighted mean of the Tibetan platform and those of southeastern China. This result confirms the 239 practical validity of regionalization of surface waves. 5. Crustal tliickness in northeastern China is ap proximately 30 km, and the upper mantle structure is com parable to that of southeastern China. 6. Crustal thickness in central China is nearly 40 km, and the low—velocity zone in the upper mantle is at a greater depth but more prominent than that of northeastern China. 7* Crustal thickness in northwestern China is ap proximately 45 km, and the upper mantle structure strongly resembles that of the Tibetan platform. 8. Crustal thickness in Mongolia changes rapidly from about 35 km to 60 km eastward in eastern Mongolia, and the upper mantle structure also is comparable to that of the Tibetan platform. By correlating the geology, seismicity, gravity anomaly, and the resulting crustal and upper mantle structures, the major conclusions concerning the tectonics are: 1. There are linear correlations between Bouguer anomalies and crustal thicknesses in the areas of eastern China and areas of western China and Mongolia, indicating a uniform crust-mantle density contrast in each of the two regions. The equal intercept thickness at the zero Bouguer anomaly, however, suggests a higher average upper 240 mantle density in the areas of eastern China than the areas of western China and Mongolia. 2. Extreme Bouguer anomalies associated with the Tibetan platform, northwestern China, and Mongolia are a result of subduction of low density crustal materials into the mantle, and 3. 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S. and Sung, Z. A. (1963), Phase Velocity of Rayleigh Waves in China: Acta Geophysica Sinica, v. 12, no. 2, p. 148-165. 246 Tseng, J. S. (1974) > Gravity Compensation of the Mohoro- vicic Discontinuity and the Basic Model of Crust Structure: Acta Geophysica Sinica, v. 16, p. 1-5* U. S. Air Force (compiled), A Bouguer Anomaly Map of Asia, 1971* Woollard, G. P. (1972), Regional Variations in Gravity: The Nature of the Solid Earth, p. 463-505* Woollard, G. P. and Strange, W. E. (1962), The Relation of Gravity Anomalies to Surface Elevation, Crustal Structure and Geology: Univ. Wis. Geophys. and Polar Res. Center Rept. 62—9* P* 350. Zonenshain, L. P. (1973)» The Evolution of Central Asiatic Geosynclines through Sea-floor Spreading: Tectonophysics, v. 19> P* 213-232. 247 APPENDICES Appendix I Derivation of th.e Time Attenuation by Gaussian Filter (after Dziewonski and Hales, 1972). 249 APPENDIX I Derivation of the Time Attenuation by Gaussian Filter (after Dziewonski and Hales, 1972) A surface wave train of single mode can be expressed by the following form: f(t) = ~ j" A(w)H(w)ei(kr-Wt+<P)dw - 00 if both amplitude and wave number k can be approximated by first-order Taylor’s series near the vicinity of w q, A(w) = A(w ) + A 1 (w- w ) o o k(w) = k(w ) + k1 (w-w ) o o where A t _ k1 = dA dw dk dw w=w w=w and e-a(w-w0/w0) H(w) = w-w ^ w o o w-w > w o o 250 then r W W - W o 2 r tl v A(w0) | o --o' -(------ ) i(k(w ) r + k (w-w )r-wt+cp) f (t) - — ---- I e w e o o 2 7T I o dw -w o / W ° — of ( Wl^— ) + i [ k7 (w-w )r-wt+cp ] e w o k o dw - w o If we assume that the initial phase 9 can be ignored for our discussion, then w „ #il A(w0) ik(w ) r f ° -a ((-^- ) ^ -2-^-+l)+ik'wr-ik'w r-iwt f (t) = — e o / e w w o 2 ir / o o d w -w o w A(wn) ik(w )r-ik7(w )r C ° -a( —— )^+2g? —— +i(k7 r-t)w+ o? =—r— e o o / e w w 2 tt l o o dw - w o w A(w0) ik(w )r-ik/(w )r f ° [-»(— - ) + (2-^— Hik/r-it)w-a ] =— e o o / e w w , 2 TT / o o dw -w o = A(wn) ik(w0)r-ik,(w0)r f ° - f f [ ( - ^ “ —---— e I e w 2 TT J o W / w )2 -2 W lk rwn itw0 )|1j w za zo ° dw -w o .w A(wo) ik(w )r-ik;(w )r / -c^ _------- e o o / e TT W r - w o r/ w ).(l| ik'rwo ,itw°)]?- W Z<2 Z<2 O - ik-rWQ _ltw^)+1] Z<2 Zff dw 251 Apply the Steepest decent approximation, A(w0) ik(w )r-ik (w )r i , i , lwo ,, / , x >2 ^ e o o tt. 2 +o? | H (k r-t) r-or 2tt (~) e 1 — " 5 zor o A W „ik(wo)r-ik'(w0)r ^ i (k/ r_t))2 (k/_r_t) -IT ( — ) e za o . e a A(w0) eik(wo)r-ik7(w0)r 2 tt ¥ e 2i=a-(k' r-t) TT.-i Of O “ W0 , , / ^2 e— 7^— (k r-t) 4a o Xt is seen from this last expression that the time domain attenuation is ( k' r - t)‘ e 4a o or ( t - t) 2 e 4 a If we define k7 = o u t = u o o o When t = t this factor becomes unity, and f(t) has a maximum at t = t , which is the group arrival time for energy of* frequency w q . 252 Appendix II, Definitions of the Duration in the Time Domain and Frequency Domain, 253 APPENDIX IX Definitions of* the Duration in the Time Domain and Frequency Domain Following Papoulis’s (1962) notation, if* function f'(t) has the Fourier transform F(w) = then the duration of f(t) is defined ass 0 0 D t = J - 0 and function of F(w) is defined t |f(t) I ^dt time Appendix III. Energy Integrals and the Partial Derivatives of* Phase Velocity 255 APPENDIX III Energy Integrals and the Partial Derivatives of* Phase Velocity The detailed derivation is given by Tacheuchi, et al. (1964). For spherical earth, the fundamental equation for Love wave i s: (wa)2^ + I2 - N 2I 3 = 0 (33) I, = J 1 dr 2 o 2 2 I_ = f g_f dr 3 Jo 53 3 where gx= p, g2=g3= n. fx= r\2 , f2= y 2 + 2ryiyi-r2yi 2, 2 2 f - and N = n(n+l) . 256 To obtain the partial derivatives of phase velocity with respect to the layer parameters a, (3, P , the first step is to obtain the partial derivatives of phase velocity with respect to elastic parameters p, a, pi * then use the chain rule of differentiation to carry out a transformation. ^ w a / \ To do this, substitute < - ■ = —r into equation (33) n+ 2 and differentiate with respect to p and u, we have 5C = -C(n+£) lx2 r+e 2(n+i) CI1 r-e f^dr (3*0 9C r+e (C-f2+N2f3)dr (35) 2(n+|-) CI1 r-e where e is the half layer thickness. Then use the trans formations p = p\ = p(32-2(32)pt = p(32 /SC \ = /ac\ /ap\ \ap/p,a \sp / \,pi \B(3/P,a + 257 , 3c v , ac x . 2 „ ,ac , tQz, ac , (ir)o. p = ( _ 8r) x.n (a p ) ( ^r)p . n + p (^rV , 9C = ? 9C_ ( 8or ) p , P P 9 X. p> M - we have , 9C . _ PB______ r r+e . , , ..2 ( d a }D,a (n+ * )<*CL. J ( ' 2 N f3) r p,« Jr_ , SC _ 1 r r+e (3^_____ r r+e ( 3p a , p 2 L ^ 1 r 2(n+ ^ ^ 1 r-e 1 r-e For Rayleigh, waves, the Fundamental equation is (wa)2(I1 + N2I2) - ( I3 + I6) + (2I4- I? )N2-(I5 + 2Ig) N+0 and the energy integrals are: I = f g.f dr for i=l, 2,......8 1 J o 11 2 2 gl=g2 = p’ g3 =g4=g5=X * ^5 = g7 =g8~*^ * fl=r yl * £2 = rZy 3 Z » f3 = (ryi+ 2yi)2 ’ f4 = (ryi + 2yl)y3 ’ f5=y32 ’ f 6 = 2 ( r V + 2ylZ) ’ fr yl2-y32-6yly3+ 2ryly3 + 2 ryly3”2ry3y3 2 2 2 +r y3 and fg-y3 • (37) (38) (39) 258 Similar to the Love wave, we evaluate the partial derivatives of phase velocity with respect to elastic parameters first: Ce (v N % ) d r O p . Cle ( v2 n VA> d r O p. X = ' 2(n+V)^C(i1+N 2I2) dr and use the same transformation as shown in (^), (5)> and (6), we have: ' l r ' - ^ 2 C H i jc,ilt^ i z) /;_+ ; < v n V n“v ' 2(n+^ ^ Cfl^+N^ ^r-e (f3‘2N f4+N V (7T-)a O = - 0,T xCm 2t ' f r + e dr 3p 3 , (3 " 2(1 + N 2I2) / r-e +<9 ~2Pm )----- 2— r / r+e (f,-2N2f +N4f ) dr Zfn+Jt^Cfl +NZI ) 1 r-e 3 4 5 1 U +---- r4““7 ---- 7— T“ I r+0 (f,+N*£_+2N*fQ) dr 2(n+^^C(L+N^I0) J r-e 6 7 8 1 2 259 2(n+f)2C(I1+I2 Appendix IV, Partial Derivatives of* Group Velocity and High—order Group Velocity* 261 APPENDIX IV Partial Derivatives of Group Velocity and High—order Group Velocity Partial Derivatives of Group Velocities Using the notations of Tacheuchi, et al. (196^) given in Appendix III, the partial derivatives of group velocities are derived as follows: For Love waves du dp a, | 3 /3(yci^\ \ 5p /a, = (513/5p)5,B . _J3_ 3C _ i3_ CI1 c^i a,!3 Cl2 \SP/a»P (a, s A [(£ )*.„♦ *(£),. J \d|3/a, in which is partial derivative of group velocity with respect to density while holding a and | 3 constant. 262 Rayleigh, wave case: For briefness, let us define: m = f + N2f2 n2 = f0 - 2N^f. + N4fc 3 4 5 IB = f. + N f + 2N4fD O f O 2 S = I + N I2 2 2 SN = (n + 0. 5) C(I1 + N I ) U1 = (I? = 2I4) + 2N2(i5 + 2lg) - (aa)2I2 then 263 u u l C • S 8p a , (3 8p C • S a , p ^ 3 ( u l ) ^ _ _ u _ 8 C ^ C » S 8 p 06, (3 C 8 p cx, p 8p 06 , P c h ^ i ^ K + <*2-*2> < 1^ > x> C«S8p 8jj, p, \ ) JL(-2c_ C v 8p 06, p u r , 8 S [ < — V , u +,s - 2 p l f 3 ( S ) 3 \ p, p- + P2(-|^ , 9 ( i p, X J 9 (4^r) 8 P p, a 8 P O S p , a _ J , 8 ( u l ) u 8 C C * S 1 8 p p , a ' C 1 8 p p , a S ' 8 p p» 06 2 P p 8 ( u l ) 8 ( u l ) C - S L 3 |a p , X ' 9 X p, | l ] u _ 9 C 2P P u r 9 ( S ) 2 ( — ) C 1 9 P p, a " S 1 1 p, X 9 X p , ^ ] 264 1_ 3(ul) u ac C ( da u c v aA p , p p, P s 2pa a( ui) c. s ( a \ p ,|a u_ _ac c a < a ? 2Pern as . p, ( 3 S a \ p, |a Thus, a group velocity change resulted from a small varia tion in layer parameters can be calculated from these derivatives when contributions are summed over all the layers: through a direct integration of the energy integrals. To check the validity and the practical value of the method of using partial derivatives of the group velocity, we have presented in Tables 1 and 2 group and phase velocity perturbation values calculated from the above two ap proaches, namely, from the partial derivatives and from the energy integrals for a small perturbation of layer i ( 3p * d, p Same group velocity change should be also resulted 265 Table 1. Modification of Gutenberg Model by increasing first layer shear wave velocity by 0.064 km/sec Rayleigh Wave (km/sec) N U(G) u(m) A U A U' C(G) c(m) . . . A C __ .AC* 100 3.83343 3.83753 .0041 .0026 4.10648 4.IO867 .00219 .0027 120 3.86842 3.88222 .01380 .0031 4.06828 4.06839 .00031 .0031 138 3.90318 3.90695 .00377 .0036 4.04299 4.04335 .00236 .0036 150 3.90868 3.91374 .00306 .0038 4.03144 4.03465 .00321 .0037 165 3.91623 3.92454 .00829 .oo4i 4.02124 4.02360 .00236 .oo4i 183 3.90647 3.91143 .00496 .0043 4.00937 4.01239 .00302 .0043 200 3.89268 3.89353 .00083 .0049 4.00165 4.00555 .00390 .0049 230 3.81606 3.83527 .0192 .0704 3.97325 3.97296 .00029 .0064 282 3.70431 3.72050 .01399 .0768 3.94686 3.94772 .00086 341 3.51019 3.32224 .01203 .0109 3.88230 3.88673 .00443 .0109 428 3.28039 3.31201 .03162 .0179 3.76834 3.77538 .00684 300 3.18464 3.23068 . 046 .023 3.67069 3.68572 .01303 .012 AU, AC: Velocities changes calculated from energy integrals. AU',ACf: Velocities changes calculated from partial derivatives. (g ): Gutenberg earth model. (m ): Modified from Gutenberg earth model. to o a Table 2. Modification of Gutenberg Model by increasing first layer density by 0,035 g/cm^ Rayleigh Wave (km/sec) N U(G) .. U(M) AU A Uf _C(G) c(m) A C A Cf 100 3.833^3 3.83121 ,00222. 4.10648 4.10539 .00109 .00102 120 3.86842 3.87506 ,00664 ,0063 4.06828 4.06555 .00273 .00070 150 3.90868 3.90531 .00337 .0080 4.03144 4.03010 .00134 .00070 165 3.91625 3.90051 4.02124 4.02183 .00059 A U, Ac: Velocities changes calculated from energy integrals, AU1, A C1: Velocities changes calculated from partial derivatives, (G): Gutenberg earth model, (M): Modified from Gutenberg earth model. to o o parameter's. In general, the phase velocity perturbation calculated from both approaches are in good agreement with each other. The differences of group velocity calculated from the two approaches are, however, large and unstable. The deviation could be as high as 500 percent. These discrepancies may indicate that while little errors are introduced into the calculated group velocity values when the approximated formula U = dw/dlc is used, yet the numerical differentiation of U would amplify the errors to an untolerable degree so as to make the partial derivative method impractical. Further dis cussions will be given in the next section. High—order Group Velocities To investigate why there are considerable devia tions in group velocity change as calculated from the partial derivatives of group velocity, it is necessary to reconsider the original definition of the group velocity. Group velocities are calculated from the formula dw U = regardless of whether they are obtained from method of differentiation or from energy integrals. This formula dw r / is derived from the relation U = = — (Ewing, et al. , 1957; Lamb, 19^5) when first order approximation is made of wave number k (see Appendix l). If the group velocity 268 is considered as the rate of energy propagation, one should define group velocity by U = r/t (40) and then U t T dk To see why, let us assume that a surface—wave train can be expressed as f (t) = J - f- A (w) e i(kr - Wt + ® >dw.................. (kl) C . T T -co When evaluating this integral by the stationary phase method, one seeks the solution of -7— ( wt - kw) r - cp ) = 0 ................................ (^2) dw x If we expand the wave number k into a Taylor*s series in the neighborhood of w , (^2) becomes 2 2 3 3 d ( 2 , , , dk0 d kQ (w-w0) , d k0 (w-w0) , n ^ !wt - (ko + d^f( W -Wo) — 2— + d ^ — 5- ^ +...]r-«p}=0 o r _ L . [ 4 1 S a _ + (w_ w , + 4 - % i - ( 2 Z 2 2 Q } +. . . .] = 0 r dw dw^ o dw-J 2 From (^+0) we see that 1 dk0 . d^kn , » . d^k^ (w-wn)^ . (^3) 2 + d k o (w.w > + Jw=2 d + r d w^ o dw-3 2 u dw I c if we let k/= — , then dw 2 1 k//(w-wQ ) k///(w-wQ)^ (k//(w-wQ))^ (k/ / / (w-wp)^ ( ) U _ k' ' (k')2 ~ (k')2 (k')3 (k')3 269 dw 1 From this relationship it is seen that U = = — t is indeed a first order approximation. Expression (44) will dw be defined as high—order group velocity, and U = will be termed as first-order group velocity. By virtue that U is the velocity of energy propagation, series (44) must be convergent. The ratios of the second and third terms relative to the first term in equation (43) have been shown in Chapter 3 where the nature of band-filter is dis cussed. In general, the first term is predominant over the other terms. Hence, the error introduced in the first- order group velocity is probably not severe. However, when their derivatives are calculated, the errors can be large because of the omission of higher order terms, which may contribute substantially to the group velocity deriva tives . 270 Appendix V Seismograms and Two-dimensional Plots from Milltiple-fliter Technique 271 APPENDIX V Sexsmograms and Two-dimensional Plots from Multiple—filter Technique In the following pages, seismograms are first list ed, and followed by the corresponding two-dimensional plots# The date of earthquake and the recording station are indicated on each seismogram and plot# 272 Wave Path. Page Number Two Table of Seismo- Dimensional Group gram__________Plot Velocities LAH COMP h February 3* 1966 2 72 273 307 NDI COMP b February 5* 1966 272 27b 307 NDI COMP b September 28, 1966 272 273 307 CHG COMP b June 15, 1971 272 276 307 LAH COMP b August 309 1967 277 278 308 LAH COMP 4 September 28, I966 277 279 308 ANP COMP b February 13* 1966 277 280 308 ANP COMP b February 7* 1966 277 281 308 ANP COMP 5 February 13» 1966 282 283 309 ANP COMP 5 February 3» 1966 282 284 309 NDI COMP 3 September 28, 1966 282 283 309 273 Wave Path.______________________________Page Number Seismo- gram Two Dimensional Plot Tab1e of Group Velocities NDI COMP 5 February 5, 1966 282 286 309 ANP COMP 5 February 7* 1966 287 288 310 LAH COMP 5 September 28, 1966 287 289 310 SHI COMP 5 March 23, 1966 287 290 310 LAH COMP 5 March 23, 1966 287 291 310 SEO COMP U February 5, 1966 292 293 311 HKC COMP k January 20, 1967 292 294 311 SEO COMP h February 7, 1966 292 295 311 HKC COMP 6 January 18, 1967 292 296 311 SEO COMP k February" 13, 1966 297 298 312 ANP COMP h November 13, 1965 297 299 312 274 Wave Path Page Number Two Table of* Seismo— Dimensional Group gram_________ Plot_______Velocities BAG COMP U January 20, 1967 297 300 312 HKC COMP January 18, 1967 297 301 312 CHG COMP k January 20, 1967 302 303 313 CHG COMP h June 16, 1973 302 30k 313 CHG COMP h January 18, 1967 302 305 313 LAH COMP k March 7* 1966 302 306 313 275 r n — I5TA.1AM P .QMP ^ '4) — DATE t-.h-J.rtb, Haj 150 :STA N D I "COMF t i± 2 _ f : f ATF - , pt.^8 .<££___ I 1 5_ ~J_P ^ °NC rjT A C tili-X O M P T <T) f -TATE Zius a.iffl rw, um J : "r 3-Q_ T, .pi GPM ~) MCT i f 276 D$8D GROUP VELOCITY Ikm/sec) 13* \5 . 1 8 . 2 2 * 2 5 . 2P« PERIOD (second) 39. A 2• 46 . £2 . £>6. 7 1 . 7 6 . 8 2 . 8 9 . 9 B . lO 8 . 1 2 0 . 1 5 40 65 120 4.0 3.5 3.0 2.5 LAH vertical component: Fsbnuery 1966 277 GROUP VELOCITY (km/sec) PERIOD (second) 1 1. 12. 13 . 1 5. 1 8 . 2 2 . 2 5 - 2 8 . 3 3 . 39. 42 • * 6 . 5 0 . 5 5 . 6 2 . 6 6 . 71 . 7 6 . 8 2 . 8 9 . 9 8 .1 0 8 .1 2 0 . 4. 1 34 4. 109 4.08 1 4 . 056 4 .0 30 _ _ 4 . 0 0 5 A o 3 .9 80 * ,W 3 . 9 56 3.931 3. 908 3 .6 84 3.86 1 3. 837 3 .8 1 5 3. 792 3. 770 3 .7 4 3 3. 726 3 .7 0 5 3 .6 8 3 3 .6 6 2 3.6 4 2 3. 621 3.601 3.581 3 .5 51 3 .5 2 2 - 2 rr 3 .4 9 3 0 . 0 3. 465 3 .4 3 7 3 .4 1 0 3. 383 3. 356 3 . 3 30 3. 304 3 .2 79 3 .2 54 3 .2 3 0 3 . 206 3 . 182 3 » 158 3. 1 35 3 .1 1 3 3 . 090 3 .0 6 8 3. 046 3 .0 2 5 _ ~ 3 .0 0 4 * (J 2 .9 9 3 ^ 2. 962 2.9 4 2 2 .9 1 5 2.9 8 9 2 .8 6 7 2 .8 4 2 2. 817 2 .7 9 3 2 .7 7 2 2.7 4 8 2. 725 2. 702 2 .6 8 0 2 . €57 2. € 36 2 .6 1 4 2. 593 2 .5 7 3 2.5 5 2 2. 532 2 .5 0 7 2. 483 2 .4 5 9 2. 436 2. 4 13 2. 391 2 .3 6 9 2 .3 4 7 2 .3 2 6 2 . 305 2 .2 95 2.2 6 5 2 . 241 2 .2 1 8 2 . 195 2. 1 73 2 . 1 51 2 . 1 30 2. 109 2.5 N D I vertical component February 5 1966 14 . 3 4 . 4 3 . 4 7 . 5 1 . 5 5 . 5 7 . 5 7 . 5 7 . 5 4 . 4 7 . 4 0 . 3 2 . 2 5 . 15. 3 7 . 4 8 . 5 1 . 5 5 . 5 6 • 4 9 . 4 1 . 3 3 . 2 5. 16. 4 0 . 5 2 . 5 6 j 59> / 5 T . 6 5 . 6 4 . 6 3 . ^ 5 ^ . 5 1 . 4 2 . 3 3 . 25 . 18 . 4 4 . —6UT" 6 * . 6 7 . 6 8 . 6 8 . 6 6 . 6 f \ 5 3 . 4 3 . 3 4 . 2 6 . 19. 4 7 . /6 1 . 6 5 . 6 8 . 7 2 . 7 2 . 7 1 . 69 . 634 5 4 . 4 4 . 3 4 . 26. 2 1 . 5 1 . / 6 5 . 7 0 . 7 3 . 7 5 . 7 6 . 7 4 . 7 2 . 6 5 . \ 5 5 . 4 5 . 3 5 . 26. 2 3 . 5 5 / 7 0 . 7 4 . 7 7 . 7 9 . 7 9 . 7 8 . 74. 6 7 .V 5 6 . 4 5 . 3 5 . 26. 2 5 . 7 4 . 7 3 ^ -8 1 • “a 3 i 7 6 . 6 8 . \ 5 7 . 4 6 . 3 5 . 2 6 . 2 7 . 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P 344 72U ST'S. / f T i 8 6 . 8 5 ^ 8 . 6 S . / 5 4 . 3 9 . 2 7 . 2 2 . 2 1 . f 27j[ 6 8 t R 0 . / 7 0 . 7 2 .V 8 2 . 7 4 . 6 4 / 5 1 . 3 6 . 2 3 . 2 0 . 2 0 . 1 9 .\ 6 4 . / 7 4 / 6 2 . 6 5 . 7 8 . 7 7 . 7 0 . 6f/m 4 7 . 3 3 . 2 0 . 18 . 19. 12. 61 * 6 / 1 « 5 > € 8 . 7 3 . 7 3 . f 5 * / 5 6 . 4 4 . 3 0 . 17. 16. 19. 1 1 • \ 60 J 6 3 . /4 4 . 5>,. 6 9 . 6 8 . 6L< 5 1 . 4 1 . 2 7 . 1 3 . 1 4 . 19. 1 8 .1 6 0 . 8 • / 3 5 . 44V 6 5 . 6 4 . 5 6 . 4 7 . 3 8 . 2 5 . 10. 1 3 . 19. 27 mi 6 1 * *»4 •/ 2 6 . 3 9 .^ 6 1 . &{/• 5 2 . 4 3 . 3 5 . 2 4 . 7 . 12. 2 0 . 3 7 J 631 S i / 1 8 . 3 4 . 5 8 T ^5 6 . 4 7 . 3 9 . 3 3 . 2 3 . 5. 12. 21 . 4 7 / 651 / . 1 3 . 3 1 . 5 5 . 5 2 . 4 2 . 3 5 . 3 1 . 2 2 . 6 . 13. 2 2 . ^ 57 . 6 71 kP. 1 3 . 3 0 . 52 . 4 8 . 3 7 . 3 0 . 3 0 . 2 3 . 9. 15. 24 . 63. 68 1 IT* 1 7 . 3 1 . 50* 4 5 . 3 2 . 2 6 . 2 9 . 2 4 . 12. 18 . 27 . 6 9 . 68 J >f6. 2 3 . 3 3 . 4 9 . 4 2 . 2 7 . 21 . 2 8 . 2 6 . 1 7 . 2 1 . 30 . v 7 3 . 67 J W6. 2 9 . 3 6 . 4 8 . 40 . 2 3 . 1 7 . 2 8 . 2 8 . 2 1 . 2 5 . 33. \ 7 6 . 631 6 . 3 4 . 4 0 . 4 8 . 3 8 . 1 8 . 1 3 . 2 8 . 3 1 . 2 6 . 2 9 . 37 . \}7 8 . 5 SW US. 4 0 . 44 . 4 9 . 37* 1 6 . 10. 2 9 . 3 5 . 3 2 . 3 4 . 4 2 . U78. 50 J > k3 • 4 5 . 4 9 . 5 0 . 38 . 1 6 . 1 1 . 3 2 . 3 9 . 3 7 . 4 0 . 4 6 . \i77. 4 1 i k l. 4 9 . 5 3 . 5 2 . 4 0 . 1 9 . 16. 3 5 . 4 3 . 4 3 . 4 5 . 51 . 177. 30» *0 • 5 3 . 5 8 . 55 . 43* 2 5 . 2 2 . 3 9 . 4 8 . 4 9 . 5 1 . 57. \P7. 20U UO. 5 8 . 6 3 . 59 . 4 7 . 3 2 . 3 0 . 4 4 . 5 3 . 55 . 5 7. 62 . 2CU 4 2 . 6 2 . 6 7 . 6 3 . 5 2 . 3 9 . 3 8 . 5 0 . 5 9 . 6 1 . 6 3 . 6 7 . 181 314 h 6* 6 6 . 7 1 . 6 7 . 58 . 4 7 . 4 6 . 5 6 . 6 4 . 6 7 . 6 9 . 72. S36.\464 Ete. 6 9 . 7 5 . 7 2 . 6 4 . 5 5 . 5 4 . 6 2 . 7 0 * 7 3 . 7 4 . 78. B 9 . 7 3 . 7 9 . 7 7 . 7 1 . 6 3 . 6 2 . 6 9 . 7 6 . 7 9 . 8 0 . 82 . 9 6 . ^ 3 4 \ 7 7 . 8 3 . 8 3 . 7 9 . 7 3 . 7 3 . 7 8 . 8 3 . 8 5 . 8 6 . 8 8 . 1 0 0 . 9 1 . 7~&\ 7 9 . 8 7 . 89 . 8 6 . 8 2 . 8 2 . 8 6 . 9 0 . 9 1 . 9 2 . 93 . \ 9 7 . 1 0 0 • ayi 7 9 . 88* 96 . 96 . 9 4 . 9 4 . 9 6 . 9 0 . 9 8 . 9 8 . 9 8. 9 7 ./ 7 8 J 7 6 . 8 7 . 9 7 . 9 9 . 9 8 . 9 8 . 9 9 • 1 00 . 1 00 • 1 00 • 1 00 . 7 9 ^ 2 0 / ^ 7 2 / 7 1 . 8 5 . 9 7. 1 00 . 1 00 . 1 00 . 1 00 . 1 00 . 1 00 . 1 0 0 . 1 00 . > 6 8 . 79S 62> 6 4 . 8 1 . 9 6 . 9 9 . 9 9 . 99 . 9 3 . 9 6 . 9 8 . 9 8 . 98 . 5 b ^ 6 7 . 5B . 5 5 . 7 5 . 9 3 . 9 6 . 9 7 . 9 6 . 9 4 . 9 4 . 9 4 . 9 6 . 96. 4 4 . 5 0 . ^ 3 7 . 4 6 . 7 0 . 8 8 . 9 2 . 9 2 . 9 0 . 8 8 . 8 8 . 9 0 . 9 1 . 9 2 . 3 4 . 4 6 . 2 4 . 3 8 . 6 4 . 8 3 . 8 7 . 8 6 . 8 3 . 8 1 . 8 1 . 6 3 . 8 6 . 8 7 . 2 8 . 3 9 . 1 2 . 3 0 . 5 8 . 7 7 . 8 1 . 7 8 . 7 5 . 7 1 . 7 2 . 7 6 . 80 . 81. 2 5 . 3 5 . 4 . 2 5 . 5 2 . 7 2 . 7 4 . 7 1 . 65 . 6 1 . 6 3 . 6 9 . 7 3 . 74. 26 . 3 3 . 8 . 2 2 . 4 8 . 6 6 . 6 7 . 6 3 . 56* 5 1 . 5 4 . 6 1 . 6 7 . 6 8 . 29 . 33 * 13 * 2 0 . 4 4 . 6 0 . 6 1 . 5 5 . 46 * 4 0 . 4 5 . 5 4 . 6 0 . 6 0 . 3 3 . 3 4 . 1 5 . 1 9 . 4 0 . 5 5 . 5 5 . 4 8 . 38 . 3 0 . 3 6 . 4 7 . 5 3 . 5 3 . 3 7 . 3 5 . 15. 18 . 3 8 . 5 1 . 50 . 4 2 . 3 0 . 2 1 . 2 9 . 4 1 . 4 8 . 47. 4 1 . 3 5 . 1 2 . 1 7 . 36 . 4 7 . 45* 3 7 . 2 5 . 1 2 . 2 2 . 3 6 . 4 2 . 4 1 . A . 94 1 f O . 96 Pro. 98 9 8.1-60' 9 4 .1 0 0 1 0 0 8 3 \ 9 9 7 \ \ 9 7 6 6 V \ \3 1 OO . 9 8. 9 7 .1 0 0 278 GROUP VELOCITY ( k m / s e c ) f NDI v e rtic a l com ponent S ep tem b er 2 8 1966 86* / 'B . / 6 7 J 52 • 34 • 2 3 . 22* 825 / 75 / 65 / 50 • 3 2 . 2 1 . 21* 7 2 jL 6 3 1 4 8 . 2 9 . 1 9 . 2 0 * 7 4 . Jtt9 . 6 1/. 4 6 . 2 7 . 17 . 19* 6 6 . 4 4 . 2 5 . 1 5 . 19. 6 5 . 6 3 > ^ 5 7 . 4 3 . 2 3 . 1 4 . 1 8 . •"S7T'--38. 5 4 . 4 0 . 20 . 1 1. 17. 5 0 . 5 3 . 5 1 . 3 9 . 17 . 8. 16. 4 2 . 4 8 . 4 9 . 3 7 . 16 . 6 . 16. 3 4 . 4 4 . 4 7 . 3 6 . 1 5 . 5 . 1 6 . 2 6 . 41. 4 6 . 3 6 . 16. 6 . 17 . 1 9 . 38. 4 5 . 3 6 . 17 . 9 . 18 . 1 3 . 36 . 4 4 . 3 7 . 2 0 . 1 2 . 19. 1 0 . 3 5 . 4 4 . 3 8 . 2 3 . 15 . 2 1 . 1 4 . 3 5 . 4 4 . 3 9 . 2 6 . 1 9 . 2 4 . 2 0 . 3 6 . 4 4 . 4 0 . 2 9 . 2 3 . 27 . 2 6 . 3 8 . 4 5 . 4 2 . 33 . 2 7 . 3 0 . 3 2 . 4 0 . 4 5 . 4 3 . 3 6 . 3 1 . 34. 3 6 . 4 2 . 4 6 . 4 4 . 3 9 . 3 5 . 3 8 . 4 3 . 4 4 . 4 6 . 4 5 . 4 2 . 4 0 . 4 3 . 4 8 . 4 6 . 4 5 . 4 6 . 4 5 . 4 5 . 4 7 . 51 . 47 . 4 4 . 4 6 . 4 8 . 4 9 . 5 2 . 5 6 . 4 6 . 3 9 . 4 3 . 5 4 . 6 0 . 6 3 . 5 7 . 4 4 . 3 4 . 4 1 . 5 6 . 6 4 . 6 8 . 57 . 4 2 . 2 9 . 3 9 . 5 8 . 6 8 . 7 3 . 57 . 3 9 . 2 2 . 3 7 . 6 1 . 7 3 . 7 8. 5 7 . 3 6 . 15 . 3 6 . 6 3 . 7 7 . 8 2 . 5 8 . 3 4 . 6. 3 6 . 6 6 . 8 1 . 86. 5 9 . 3 4 . 3 . 3 8 . 6 9 . 8 4 . 8 9 . 6 1 . 37 . 1 4 . 4 2 . 7 3 . 8 8 . 9 3 . 6 7 . 4 8 . 3 5 . 54 . 81 . 9 4 . 9 7 . 7 3 . 5 9 . 4 9 . 6 4 . 8 6 . 9 7 . 99 . 7 9 . 69 . 6 3 . 7 4 . 91 . 9 9 .1 0 0 . 8 8 . 84 . 8 0 . 8 7 . 9 7 .1 0 0 . 99 . 9 2 . 9 1 . 8 9 . 9 3 . 9 9 . 9 9 . 9 6 . 9 6 . 9 8 . 9 7 . 9 9 .1 0 0 . 9 5 . 9 1 . 9 6 . IC O .1 0 0 .1 0 0 . 9 7 . 9 0 . 8 5 . 9 4 . 9 9 .1 0 0 . 9 9 . 9 3 . 8 4 . 7 9 . 9 1 . 9 7 . 9 8 . 9 5 . 8 8 . 7 7 . 72. 8 6 . 9 3 . 9 4 . 9 1 . 8 1 . 7 0 . 6 5 . 8 0 . 87 . 8 9 . 8 5 . 7 4 . 6 1 . 5 7 . 65 69 84 97 ICO PERIOD (second) 10 . 11. i i . 11. 1 1 • 10. 10. 10. 10. 10. 11. 12. 13. 1 3. 14. 15 . 15. 15. 15. 1 4. 1 3. 12. 1 1 • 9. 8. 6 . 5. 4 .2 1 3 4 . 1 82 4 . 151 4. 120 4.09C 4. 061 4 .032 4 .0 0 1 A 0 3.975 3 .9 4 7 3.91 9 3 . 892 3 .8 6 5 3 .8 39 3 .8 1 3 3.78 7 3 .7 6 2 3.7 3 7 3 .7 1 2 3 .6 6 3 3 . 640 3 .6 1 7 3.5 9 4 3 . 571 3 . 543 3 .5 2 6 3 .5 0 4 3.5 2 .4 9 9 2.5 14. 15 . 16. 1 6 . 1 6 . 1 5 . 1 4 . 1 3 . 12. 10 • 9 . 8 . 8 • 9 . 1 1 • 13 . 1 6 . 1 8. 1 9 . 20 . 2 1 . 21 • 20 • 20 . 1 9. 18. 17 . 16. 15 . 14 • 13. 12 . 10. 8. 5 . 2 . 6 • 1 2 . 16. 19. 1 9. 18. 15. 15. 18 . 23 . 3 0 . 3 8 . 46 . 279 PERIOD (second) GROUP VELOCITY (km/sec.) 1 2 0 3.5 3.0 CHG vertical component June 15 1971 280 .STA.lah c o m p z w •DATE Aug. 50 . W66 'T. 15 [po GRND M ^ A V y ^ ^ V W M w t . 96 GROUP VELOCITY (km/sec) PERIOD (second) 12. 13. 15. 18. 2 2 . 2 5 . 2 8 . 3 3 , 39 . 5 2 . « 6 . 5 0 . 5 5 . 52 . 66 . 71. 7 6 . 82 . 0 9 . 9 8 .1 0 8 .3 2 0 . 1 5 40 65 120 4.0 3.5 TjyO . 9 9 . 9 9 . 9 6 . 0 4 . 93. 9 3 ^ 9 4 ' f e - 9 9 . *T*0 5+00 ..LQO. 9 9 . 9 8 . 98 ^ f t . 9 6 . 9 7 . 9 9 . 1 00 . 1-e-O. 1 g o . 99 87. 86. 8 _ _ 9 4 . 9 7 . 9 ^ . U ^O 8 0 . 7 8 . ~ r 9 . 83. 8 8V '-9 3. 9 7. 9 9 6 6 . 6 3 . 6 2 . 6 5 . 7 3 . f t • 96 ~^7V yj > _4-5 7 o • i—SJL. 46 .✓'-39 . ~33V 3 3 > 4 4 X ^ ? . 77. 8 7 '30 3.0 2.5 LAH vertical component August 30 1967 282 PERIOD (second) 15 3 3 . 3 9 . 4 2 . 46. 40 65 9 8 .1 0 8 .1 2 0 . 120 4.0 3.5 » * * 92 -05 3.0 2.5 2 ^ '3 g . g. ?0i LAH vertical component Sept. 28 1966 283 GROUP VELOCITY (km/seci PERIOD (second) 2 5, 2 6* 3.1 . 30 * * 2 - 46* 4 0 , 5 5 . 6 2 . 66 . 4 0 6 5 120 ;4.5 : 3 . 5 3. 0 \ o A N P vertical component February 1 3 1 9 6 6 284 GROUP VELOCITY (km/sec) PERIOD (oecond) ANP vertical component Feb. 7 19 6 6 • ' t a '-.n p o.om pn-s mo . : ' h a t f B h j u a a ■ J :T. IT T ^ jc r GPlsD m c t jo f7rA!it_C0MP)l_iLiSi_ . ![ A TF F .b .y . Iict ] ■T. 15 _oc__GRND MOT J± STA. mi C O M P iK ' n DA r E ^ sa T. .F r0 JTA_GRND MOT. ; " > Mni T OMP.N.sjaL. ;rArr r-K5_u-6 avisos. 286 420441 GROUP VELOCITY (km/sec) PERIOD (second) I I * 12. 13. 1 5 . 18* 2 2 . 2 5 . 2 8 . 3 3 * 39* 4 2 . 4 6 . 5 0 . 5 5 . 62* 6 6 . 7 1 . 7 6 . 8 2 . 8 9 . 9 8 .1 0 8 .1 2 0 * 4. 834 4 . 8 0 9 4 .7 8 4 4. 759 4. 735 4 .7 11 4 .6 8 7 4 .6 6 3 4.6 4 0 4 .6 1 7 4. 594 4. 571 4. 549 4* 5 ? 7 A C 4 .5 0 5 4 5 4 .4 83 4.4 6 1 4 .44 0 4 .4 1 8 A. 397 4 .3 7 7 4 .3 5 6 4. 3 36 4 .31 5 A .295 4 .256 4 .2 1 7 4 .1 7 9 4.141 4. 1 05 4.C 69 4 .0 3 3 „ ^ 3 .9 9 8 4 0 3 .9 6 4 ‘ ^ 3. 930 3. 897 3 .8 6 5 3 .8 3 3 3 . 801 3 . 770 3 .7 4 0 3.7 1 0 3. 680 3 .6 51 3 .6 2 3 3. 594 3 .5 6 7 3 .5 3 9 3 .5 1 3 3. 486 3.4 6 0 3. 434 3 .4 0 9 3.3 8 4 3.3 6 0 3 . 336 3. ?1 3 3 .2 5 9 3.2 6 7 3 .26 4 3. 221 3. 199 3.1 7 7 3. 1 56 3 . 1 34 2.1 1 3 3.0 9 3 3. 072 3 .0 5 2 3.0 2 2 2.993 ’ 2 .9 6 5 2 .9 3 7 2 .9 0 9 2 .8 8 2 2.8 5 6 2 .8 2 9 2 .8 0 4 2 .7 7 9 2 .7 5 4 2 .7 3 0 2 . 706 2.6 8 3 2 .6 6 0 2 .6 3 7 ? .6 1 5 35 ANP N -S com ponent Februaryl3 1966 4 5 . 5 4 . 59. 4 7 . 5 7 ./€ T ; 4 9 . 5 9>T 6 3, 5 1. / f f l • 65, 53 • / 63 • 67. 55 J 6 5 . 69. 5 ^ i 6 8 . 71, '5 0 . 7 0 . 73. 6 2 . 7 2 . 75, 6 4 . 7 4 . 77. 6 7 . 7 6 . 7 9 , 6 9 . 7 1. /%0\ 82. 7 3 . 1 52 .\ 64, 7 5 . / 54 86 7 y / 0 6 . '8 7 ■ * 9 2 • 89^9O ' 8 5 . /rZm 93 8 9 - ^ 9 5 . 95 *$2. 9 7 . 97 9 4 . 9 8 . 99 9 7 .1 0 0 .1 0 0 9 8 . 9 5 . 9O T100. 5 ^ Zm 98^p0T>. 9 9 . A?. fcO* 50 > 6 . ia p r T 0 ° . 9 7 .//7 7 . / 4 5 . 4 4 . 9 9 . 9 4 / / 7 2 / 3 9 . 39 9 9 . 9 7 . 9y*i 67A 3 3 . 34 9 . 9 6 . 9 4 . > 7 / 6,6. 2 8 . 30 '7 . 9 4 t 9 C / a ? ; S t 7 . 2 3 . 26 *2 ^ -8 7 . ff6. >7^. /5 2 . 19. 22 "7. 8 1 . Q£U ^ 7 3 . / 4 7 . 15 . 18 JX*"~7S. 7 5 . 6 8 / 4 3 . 11. 15 1 . 6 7 . 6 9 . 62T. 3 e . 8 . 12 W o .1 0 0 .1 0 0 9 9 . 9 9 . 99 9 8 . 9 8 . 97 9 7 . 9 6 . 96 9 5 . 9 3 . 93 9 3 . 9 1 . 90 9 0 . 8 7 . 87 8 7 . 8 4 . 84 8 3 . 8 0 . 80 8 0 . 7 6 . 76 7 6 . 7 1 . 72 7 2 . 6 6 . 67 6 8 . 6 2 . 63 287 11 0 0 0 0 0 0 1 1 1 1 2 2 3 3 5 6 7 7 8 9 9 1 0 9 9 a 7 6 , 3 3 3 3 3 3 . 3 3 3 4 6 1 0 1 4 l a 2 I 24 26, 2 0 3 1 , ''40 54 54 i 52 46 39 32 30 33 30 25 26 /B9 (99 199 \9Q. 4 4 28 33 44 55 64 67 65 54 44 34 2 1 e 9 22 28 27 2 1 1 7 1 0 22 28 31 26 1 5 9 1 7 22 2 1 1 6 I 3 PERIOD (second) 12. 13 . IS . 18. 2 2 . 2 8 . 2 8 . 33 . 3S. 4 2 . 4 6 . SC. 5S. 62 . 66 . 7 1 . 76. 82 . « y . < 5 8 .108 .1 20 . 15 40 65 120 30. 3 6 . i S . 30. 2 2 . 14. 7. 4 . 9 . 16. 2 3 . 3 2. 3 & ^ 4 l \ 3 1 . 2 2 . 1 4 , 7. J , 9 , 1 6 , 2 4 . 3 4 . . 421 3 2 . 2 2 . 14. 6. 3. 9 . 1 7 . 2 4 . 3 7 / 4 3 . 44J 33. 2 3 . 14. 5. 2 . 10. 17. 2 4 . 3 / , 4 5 . 4 o .\ 34 . 2 3 . 14. 5 . 3 . 10 . 1 7 . 2 4 . / r i . 4 0 . 4 Q .\ 35. 2 4 . 1 4. 6. 4 . 1 1 . IP . 2 5 . 4 4. 50 . 5 0. \ 3 7 • 2 5 . 15. 7. 5 . 12. 10. 2 5 . 47. 53 . 5 2 . \ea- 2 6 » l ~« e - 7 * 1 2 * lQ - 49 . 5 5 . 5 4 . W . 2 7 . 15. 9. 9 . 13. 19. 2 6 . 52 . 58 , 5 7 . 4 1\ 2 8 . 10. 1 1. 1 0. 14. 20 . 2 6 . 5 £ 9 . 4 3 A 3 C . 19. 13. 12. 15. 2 1. 27. fc 3 • 6^>s. 4 5. \ 3 1 . 2 1 . 14. 13. 16. 2 1 . 2 7 . -63, 6 9 . 6 7 X 4 9 . 155. 2 4 . 18. 16, 19. 2 3 . 2 3 . 6 9. 74 . 7 2 . \ e i . 3>G. 2 e . 22. 19. 21 . 2 4 . 2 9 . 74 . 79 . 7 7 . "VS. 4 \ 32 . 2 5 . 2 2 . 2 2 . 2 5 . 30 . '■FC. 0 4. B TTv 6 A. 4 6 \ 3 5 . 28. 2 4 . ?4 . 2 6 . 3 0 . 0 5 . 8 9 . 8 7 . 166 \ 5 0 . >28. 30. 26. 2 47. 2 6 . 3 1 . > 9 ^—93 . '’TTn 17 0 1 5 3. 4S. 32. 27 - ? [jnr"*TV rllTw 9 3 . 96 . 9 5 . \ 7 2 . \ 5 5 . 4 2\ 33 . : 7 . 3 2 , 9 7 . 99. 9 7 .1 7 4 .1 5 7 . 4 3 1 ^ 3 ^ 7 , 25 . 2 7 . 3 3 . * fig ■Tr~MT ■ 2 7. 24 . 2 6 . 34 . 1 ? “ 1 \ 32. 25. 2 2 . 2 6 . 3 5 . ITT. 99 . 9 7 . l 7 5 . j 5 7 . 4 2 .1 3 1 . 22 . 2 0 . 2 5 . 3 6. 9 9 . 96 . 9 5 ./ 73.1 5 6 . 4L4 28 . 19. 17. 25. 3 7. 9 6 . 93 . 9 2 / 7 2 ./ 5 4 . 3*J. 26. 15. 15. 2 5 . 3 ^ . ^ / 6 9 ./ 5 3 . fc7. 23. 1 1. 12. 2 6 . /To . *T9 . 03 . 8 5 . / 6 7 J 5 1 . / 3 f . 21. 6 . 11. 2 ? . / ^ . e i T ^ T T x e c / 6 5 J 5 i . / i 6 . 20 . 5 . u . 29 ./ 4 5 , «^7. 7 1 . TTs. 63 J 5 0 .1 3 6 . 21. 9 . | 6 . 3 2 / 4 0 . 7 C • 63 . 7 1 . 6 2 1 5 1. V 8 . 2 4 . 15. 2 1 . 3 / 5 1 . 67 . €OC 5.2. 4>- 2 9. 2 2 . 2 7. y<\I . 5 b . m 4 7 \ jS 2 V *? 9 . 5 3. 4 4 . \ i 4 . 2 9. 3 4 / 4 5 , 59 . 4 9 . > * t V 5 6 . 5 9 . 5 5 . 4 2 . . 5 1 . 6 3 , 4 ; * ^ 2 9X 5 4 . - ‘3* - 6 . 53. 47. 44. 47 . 5 6 . 6 7 , / ? . 1 9 .\ 5 0 . 5 9 . 6 1 . 56. 53. 5 1 . 6 4 . 6 1 . 7 1 . 0 3 . 10. 4E. 5 9 . 6 4 . 6 3 . 60 , 5 0 . 6 0 , 6 7 . 75. 3 1. 2 . 4 7 . 6 1 . 6 7 . 6 8 . 66. 6 5 . 67 . 7 ? . 7 0. 29 . 8. 4 0 . 6 3 . 7 1 . 73. 72. 71 . 7 3. 29 . 16. 5 1. 6 5 . 74 , 7 7. 77. 7 7 . . Hh , 2 9 . 2 4 . 5 5 . 6 9 . H2 . H I. 86. 8 9 . 2 9 . 3 0 ./ 6 1 . 7 3 . 2 ^ 2 , 0 6 . 07 . 8 7. 8 b___^ / T T r ^ 'V 2 9 . 3 / 6 7. 06 . P^—'^'STT TTI 92. 9 3 . ° 5 . 2 0 . / T . 2. 94 . 94 . 9 5 . 9r,. 97 . 1 41/ 5 2 1 71 9 91 • a ’V 'O 'C i oo! i oo TVo0 I 2 5 . 5 5 .//9 7 . 99 . Ui-e-TTO^0 ■ 09. 0 9. 9 0 , 9 9 . 9 9 . 2 6 . 56 .//99 . 1 Cp<TO 0 . 9 9 . 9 0 . 9 0 . 9 0 . 9 0 , 9 0 . 2 9 . 5 0 310 0^*^50. 9 9 . 9 7 . 9 6 . 95. 96. 96 . 0 7 , 31 . S 9 ila < 'T 99 . 9 7 . 94 . 9 1. 0>. 9 3 . 9 4 . 6 6 . 33 . 5 9 * 1 9 9 . 97 . 9 4 . 9>«,—T T o " . 93. 3 6 J 69 ."\i94 • — r a I . 8 7 3 6 . 5 0. W>1 *-"37. 0 1 w ^ 6 T 73. 72. 74. T ^ K i ^ y 3 6, 56 . IrT . f i2 ^ r F . 70. 66. 66. 60. 73 . T*T. 35 . 54. l0 1| r *<7. 7 C. 64. 60. 5 9 . 62. 68. 7 0 , 3 3 . 52. VST 7 2 . 6 4 . 57 . £3. 52. 56 . 6 3 . 7 2 . 30 , 49 . 71 . 64. 5 5 . 4 7. 42 . 4? _^4 j,- 5 5 . 6 5 . 2 7 . 45 . 65 . 57. 4 7 . ^/Jc^ 3 2 . 31 . T \ 4 7. 5 9 . 2 3. 147. 59 . 5 1. 4 L / 3 1 . 23. 21. 2 8 , \ « 0 . 5 3 . 2 1 . 3 ^ 5 5 . 4 6.^277:. 2 6• 16. 12. 19 . T V 4 0 . 1 9 . 3 7 1 S I . 4 7 / 3 3 . 23. 13. 4. 13. 2 «Y 4 3 . 16. 35.1 4 7 . >*9. 3 1 . 23 . 1 4. 6 . 1 0. 2 5 -^VO . 1 9 . 33 ■ Mi 3 ^ 36 . 3 0 . 2 3 . 17. 10. 12. 2 3 . 3 7T' 2 0 . 3 1 . 3 9 . 33 . 2 8 . 2 3 . 19. 15. 16, 2 3 . 35. 21 . 3 0 . 34 . 2 9 . 2 5 . 2 3 . 2 1 . 19. 19. 2 4 . 3 4. 2 2 . 28. 29. 24. 2 2 . 2 2 . 22 . 2 1 . 2 2 . 2 0 . 3 3 . 60. 66. 65. 67. 72. 7L2* 7 3m 72. 71 . 73. 7 7. 77. 77. . 06. -F5T 02 . WZT. H3 • 86 . 09. 0 6. 07. 87. H h_ _ _ '■"OUTT*!**, p q ^-^rr;— r n 92 . <5 3 . o S . ■*J3 , 94 . 94 . 9 5 . 9 6 . 9 7 . !" * > - ■ > C "i oo! 1 oo T{"oo I 0 0 . 09. oo. 9 0 , 9 9 . 9 9 . 9 9 . 9 8 . 9 0 . 90. 9 0 , 9 0 . 9 7. 96. 95. 95, 9 0. 97. 9 4 . 9 1. 9 7. 0 2 . 9 4 . 9 5 . 9J— ■ e "'5. ''TTT^^iO • 93 . •057. 94. 8 3. 84 . 87>«jailJ W T7»T---r - T > ^ 3 . 8 7 . 70 I 66 I 6)6 ■ 6 0‘. 7 3 / 64. 60. 5 9 . 6.2. 68. 70, 57. S3. 52. 56. 63. 72. ANP N-S component February 5 19 6 6 GROUP VELOCITY (km/sec) PERIOD (second) 15 40 65 120 4 .0 3.5 3.0 2.5 NDI N component Sept. 28 1966 GROUP VELOCITY |km/sec| (%C .) 70 y/e p/. Mi I 4 S / 7i/m f 9 P s/m / n . / ? n / 9 2 /s / p y \ 9 M L 92 lj/m p<3 m 9M. 9 3 o/ p / 97.MT9. 95 f * < / m qq^roc. q7 < 4 . 1 100 * 9P q j ^ p K . < 5 < ;.lo c S6 • S 7 . 1 OC ^ q • qc . 5 1 * 9e 5 6 . ^ r r ~ p > ^ 9E 5 , 0 2 4 c r v 4 .9 8 5 (J 4 .946 4 ,9 0 9 4.87 1 4 • 835 4 . 7 99 4 . 763 4 ,728 4 , 693 4 .669 4 ,6 2 6 4 .5 9 2 4 .560 4, 5 2 a 4 .4 9 6 4 . 465 4.4 3 4 4 . 40 3 4 ,3 7 3 4.34 4 4.31 5 4 .2 86 4 .3 5 7 4.3 2 9 4 ,2 02 4 .1 7 4 4 .1 4 7 4 ,12 1 4 .09 4 4 . 069 4 .0 43 4 .0 1 8 3 .993 3 .968 3 .9 4 4 3 .9 1 9 3 • 896 3. 8 72 3# 849 3 .836 3 . 0 03 3 . 7 H 1 3 • 759 3 .7 3 7 3 .7 1 6 3 • 694 3.673 3 .6 5 2 3.611 3.611 1 .59 1 3 .5 6 1 3 .5 3 2 2.5 0 3 3 • 4 74 3 .4 4 6 3 .4 1 9 3 • 392 3 .3 6 5 3 . 3 19 3 .3 1 8 3 .2 93 3. 268 3.2 4 3 3. 2 1 9 3 .1 9 5 3 . 17 2 3 . 1 49 3 . 126 3 .1 0 3 3.081 3 . 059 3 . 0 37 3.0 16 2 .99 5 2 .974 2 .064 2 .7 1 4 2 .9 0 7 2.8 8 1 2 . 8 56 2 . 83 I 2 .8 0 6 2. 7 82 2 . 75 3 2.7 3 5 2 .7 1 2 2 .68 J 3 .6 6 7 2 . 64 5 2 .623 PER S O D (second) \ • = . 18. 22. 2*:. 15 1 • 2 m P . Pm 1 . 2 • 2. 2 . 28. 33. 2 . 3 . 35. 4 2. 40 5 • 7 . e. 8 • 46. EC. 55. 1C. 1i . 13. 11. 14, 15, 62. 66. 7 1. 6 5 13. 12. 1C. 14. 13, 11. 2* 3. 3. 1, 3 . 3 . 3 . 4 . 4 . 4 . 4 . 4 . 5 . 5 . 8 . £ . 4 • 5 • 4 . 6 • 5 . 6. 6 . 7 , 7 • 5 , 8 . 10. 5 . 12. 11. 13. 12. 16. 16. 14. IP . It?, I f . 2 C. 1 * ~ . 17. 2 2. 21. 15. 14. 1?. 17. 14. 13. 18. 15. 13. 19. 16. 14. NDI N - S component February 5 1 9 6 6 290 ''A COMP N S ■ T. 15 Tb^SJERNL MOT. J j.' IDATE tiardOL LZA%± :t. _ l ? _ T q ~ grto Mor. iL f-.TA I f.H IQMPHJUA— . ■ ' A TE MnrrK 2 3 . HU J ■ T. 15 Ta i p p _ g ^ f ) M . ; F. ^ 291 D3B 74 GROUP VELOCITY (km/sec) r PERIOD (second) 2. 66. 65 12. 13 . 1 5 . 18. 2 2 . 2 5 . 2 8 . 3 3 . 39. 42. 46 . 5 0 . 55 . 6 2 . 6 6 . 7 1 . 7 6 . a ? . 8 9 . 9 6 .1 0 8 .1 2 0 . 120 3 • e 9 6 2 .6 9 3 3 .0 9 4 A N P / i . 65 7“ 6C. 62. 6 9, 6 7 . 70 . 6 8. 6 9 . 75* 7 2 . 76 . 74 . 76>—151. 7 U ""STY HZ* • . 87 ^ 80^^<1 "'52 • 91 • 9 2 . 95 , 96 • 9 5 . 96 . 98 , (9 6 . 98 . 98 . 98 . 99 . ICC. l O U IOC. T?C. 100 1 Ott* 99.’ 9 9 . 98 , 96 • 97 . 9 7. 96, 95 . 9 2 . 9 4 . 95 . 93, 9 U - S.9Q* -S X t M l. 87. 86 , /t T T (32. 8 L 7 1 • 68 • 74 . 7 8 :‘ FT. 68 . 72. 7 1 . s f ? . 67 . 66 , 4 8 . 44 . \ 6 2 . 6 > 4 1 . 3 7. 5 C. —?7, 34 . 30 . 4 5 . §3 r 52, 2 6 . 21 • 3 9. 46. 48, 22. 1 4 . 3 3. 4 4. 44 , 1 9 • 7 . 2 9 . 40 . 4 1 1 7. 3. 2 6 . 3 8 . 4 0 1 6 • 24 • 3 6 . 4 0 1 5 • 7 . 2 3 . 3 6. 4 1 1 5 . 9 . 23 . 35 . 42, 1 5. 1 0 • 23 . 15. 44, 1 4. 1 1 . 24 . 36 • 4 6 , 1 3. 1 0. 24 . 37. 49, 1 2. 9 . 2 5 . 3 8 . 5 1 . 1 1 . 7. 2 6 . 39 . 53, 1 C • 6. 26 • 40 . 54 9. 6 . 27 • 40 . 55, 1 C . e. 2 8 . 4 0. 55 , 1 2. 1 1 . 29 . 4 0 . 54 , 1 5 • 1 5 • 3 0 . 39. 52 1 6. 20 . 3 G . 36 . 4e, 23 . 24 . 2 9 . 33. 43. 2 7. 27. 2 7. 2 8 . 36, 3 2. 30 . 25 . 23. 29, 36 . 32 . 2 3 . 16. 2 1 , 4 C. 34 . 2 0 . 1 1 . 14 . 4 2. 3 6 • 1 9 • 8 . 9, 4 6. 37 • 18. 9 , 4 9. 3 8 . 1 8. 1 1 • 1 3, 52 . 3 9 . l a . 12 . 1 6 , 54 • 4 0 . 1 6 • 12. 19, 55 . 4 C a 1 3 . 1C. 2 C, 5 7 . 4 1 . 1 0 . 6. 2 1 , 5 F . 43 . 1 1 • 8. 23, 6 C • 45 . 1 7 . 1 4. 25, 6 1 . 49 . 2 3 . 20 . 27, 6 2. 5 2 . 3 C ■ 24 . 26. 6 2. 54 . 3 5 . 2 7 . 23 , 6 1 • 56 • 3 9 . 2 e . 1 7 , 5 6 . 58 . 4 2 . 2 9 . 1 1 , 5 4 . 5 8 . 46 . 32 • 1 4 , 4 6. 5 7 . 50 • 39 • 26, 4 1 . 5 6 . 4 8. 42. 32 . 5 3 . 61 . 5 8 . 57, 2 6 . 4 9 . 66 . 6 7 . 69, 1 9. 4 6. 6 6. 73. 7e, 1 4 . 42. 6 9 . 76 . 82, 9 • 4 1 . 6 8 . 75. 02, 1 C . 4 C • 65 . 7 1 . 77 , 1 6 • 41 • 6 0 . 6 3 . 69, 24 . 44 • 53 . 5 2 . 56, 32 . 46 • 45 . 39 • 4 2, 3 fc. 48 . 39. 25 . 27, 4 3 . 5 1 • 3 3. 1 3 . 15. 49 . 53 . 3 2 . 1 4. 1 4 , 56 . 34 . 21 • 20. 6 1 • 5e. 37 . 26 . 25 , 6 7. 6 0 . 3 7 . 27 . 25. 7 1 . 60 . 33 . 22 . 21 . 7 2 . 58. 2 9 . 1 4 . 1 4 , 7 0 . 5 5 . 27 . 9 . 9. 66 . 52. 2 7 . 1 4 . 14 . .1 0 0. 98 . >100. 99 . .1 0 0 .1 0 0 . . 9 9 .1 0 0 . 9 1 . 9 0. 68. 9 8 . 9 5 . 9 9 . 9 8 . 100.1 OO • 10 0 . 1 0 0 . Component February 7 , 1966 292 GROUP VELOCITY (km /sec) 11* 12* 13* 1 5 . 18, 4 . * £ 5 A. 304 A . 36A 4. 33A 4 . 33 A 4 • ? 7 5 4 • ?47 4 .2 1 3 4 . 190 4 . 153 4 . 136 4 .1 0 9 4 • 082 4 • 055 A. 0 30 A. 00 5 3 . 980 7 • 055 3 . 9 30 3 . 9 *6 3 . 882 3 *8 5 3 3. 835 3 .6 1 ? 3 .7 8 9 3 • 7^7 3 . 7A 4 1 . 7 9 0 3 .7 * 1 3* 679 3. 65.3 3 © 637 3 • SI 6 3 .5 96 3 • 575 9 . 5 5 5 3 .5 2 5 . 3 ^ 5 ,270 , 25a 3. "9 A 2 . >33 2 . 9 6 ? 2 . 941 2 * 9-> 1 2 * 9 " 1 2 .8 7 5 2 • 34 0 2 . 0 ^ 4 2 • 7 9 9 2 . 77 A 2.750 2 • 7 2 7 ? . 7 • > 3 2.681 ,6 14 , 8 9 3 ■ 87 2 , 551 , 571 . 51 1 ?. **?3 2 • 300 2 . 3 7 1 2. 3 4 3 2 • 3 2 6 2. 9* ?6 8 PERIOD (second) 2 5 . 2 8 . 3 3. 3Q. A ft. 6 5 . 85 , 62. 6 6 . 71 . 76. 3 '. <56. 1 Oft. 1 20. 15 40 65 I 2C 3 0 1 0 2 0 4.0 36 4 2- 35 > > .K 0 .1 C C iJ C O 3 0 1 0 component Septem ber 2 8 19 86 293 GROUP VELOCITY | km/sec) 4 • 050 4 • 02ft 4 * 0 0 3 3 .9 8 0 3 .Q57 3 *9 35 3 . 9 12 3. 89 0 3 « 8ft 9 3 . 847 3 .8 2 6 3 .8 0 5 3 • 784 3 .7 6 3 3 . 743 3. 723 3 .6 9 9 3 . 675 3 . ft 52 3 .6 2 9 3 . 606 3. 584 3 .5 6 2 3 .54 0 3 . 5 19 3 .4 9 7 3 . 476 3 .4 5 5 3 . 4 3 5 3 .4 1 4 3 • 394 3.371 3 .3 4 8 3 .3 2 6 3 .3 04 3 . 282 3 .260 3 .2 3 9 3 .2 1 8 3 .1 9 7 3 • L 76 3 . 1 56 3 .1 3 3 3.1 1 1 3 .0 8 9 3 . 067 3 .0 4 5 3 .0 24 3 .0 0 3 2. 982 2 .962 2 .942 2 .9 1 9 2 .8 9 7 2 • 876 2 .854 2 • 833 2 .8 1 3 2 .792 2 • 7 72 2 .7 50 2 . 728 2 . 70 7 2 . 686 2 . 665 2 . 645 2 .6 2 5 2 .6 03 2 .5 0 2 2 . 561 2 . 5 40 2 .5 2 0 2 .5 0 0 2 .4 7 8 2 .4 5 7 2 .4 3 6 2 .4 1 6 2 .396 2. 3 75 2 .3 5 4 2 . 333 2 .3 1 3 2 .29 1 2 .2 70 2 .2 5 0 2 .2 2 9 2.200 2. I 87 2 . 166 2 .1 4 6 2 .1 2 5 2.1 04 4 . 0 3 . 5 3 . 0 2 . 5 1.0 C LOO V 9 e (second) 4 6 . 5 0 . 55 . 6 2 . 6 6 . 7 1 . 76. PERIOD 1 8 . 2 2 . 2 5 . 2 8 . 3 3 . 3 9 . 4 2 . SHI N-S m arch 2 3 Component 294 GROUP VELOCITY (km/sec) PERIOD (second) 1 2 . 13* 15* 13 * 2 2 * 2 5 * 2 8 . 3 3 . 39 . 4 2 . 4 6 . SO. 5 5 . 6 2 . 6 6 . 7 1 . 7 * . 8 2 . 8 9 . / 9 8 . 1 0 8 . 1 2 0 . 4 . 149 4 .1 2 7 4 .1 0 6 4 . f 85 4 .0 6 5 4 .0 4 4 4 .0 2 4 _ _ 4 .0 0 4 d O 3 .9 7 3 ’ 3 .9 5 2 3. 926 3.901 3 .8 7 6 3. 85 1 3 .8 2 7 3 . 80 3 3 . 779 3 .7 5 5 3 . 732 3 .7 0 9 3 .6 8 7 3.C64 3. 642 3.6 2 0 3. 599 3. 577 3. 556 3. 536 3 .5 1 5 r * r - 3 .4 9 5 0 . 0 3 ,4 7 5 3 .4 50 3 .4 2 5 3.40 1 3 .3 7 7 3. 354 3 . 331 3 .3 0 8 3. 286 3. 264 3 . 242 3 .2 2 0 3 . 1 99 3 . 1 73 3 .1 5 7 3 .1 3 7 3. 1 1 6 3 .0 9 3 3. 06 9 3 .0 4 6 3 .0 2 3 _ _ 3 .0 0 0 3 O 2.9 7 8 * 2 .9 5 6 2 .9 3 5 2 .9 1 4 2. 393 2 . 372 2. 852 2 .8 3 2 2 . 009 2. 786 2 . 764 2 . 742 2 .720 2 . 699 2 . 678 2 . 657 2 .6 3 7 2 .6 1 4 2 . 592 2 . 570 2 .5 4 8 2 .5 2 7 2. 506 2.4 8 5 2.4 6 5 2. 443 2.421 2 .3 9 9 2 .3 7 8 2 .3 5 7 2 .3 3 6 2. 316 2 . 294 2 .2 7 3 2. 251 2.231 2.210 2. 190 2 .1 6 3 2. 147 2.5 LAH N-S com ponent M arch 23 1966 dm. 1 c o 9 9 . 98 9 8 . 96 95 . 9 ^ 2T0. ^55. 51 • 47. 43. 39. 36. 33. 31. 30. 2 9 . 2 0. 2 3 . 2 8 . 2 8 . 2 8 . 27. 26. 25. 23. 21 • 1 9. 21 • 2 5 . 2 9 . 3 4 . 4 0. 4 7 / 120 62 . 295 ST A .S E P CO M P .Z <*>_ f DATE r-<_b. 7. IU 6 _1 - ____________ ■ . . - .___- ■_ ■ - Tu JS To j:o GRMD MOT, up _ a m hkc i.u m k h-v c& > . DATE J o n -ia .n t-T is o j -T._15_ "Iq J£L_GRMD M O TJL GROUP VELOCITY (km/sec) 12. 1 3 . - * .5. 4 .5 1 7 4 .4 8 5 4 .4 5 4 4 .4 2 3 4 .3 0 3 4 .3 6 3 4. 3 34 4 . 305 4 .2 7 6 4 .2 4 8 4 .2 2 0 4 . 1 *52 4 • 1 ft F 4 .1 3 8 4 .1 1 2 4 .0 86 4 • 0 60 4. 0 34 4 .0 0 9 3 .9 8 4 3* 960 3*936 3 .9 1 2 3 .8 8 8 3 .8 6 5 3 .8 * 1 3 .8 1 9 3. 796 3. 774 3 .7 5 2 3 . 730 3 .7 0 8 3. 6Q7 3 . 666 3 . 645 3 .6 2 5 3. 604 3 . 584 7 .5 5 5 3 . 5 25 3 . 497 3 .4 6 9 3 .4 4 0 3 .4 1 3 3 . ? 86 3. 359 3 .3 3 3 3 .3 0 8 3 .2 8 ? 3 .2 5 7 3 .2 3 3 3 .2 P 9 3 .1 8 5 3.161 3 .1 3 8 3 .1 1 5 3 .0 9 3 3 .0 7 1 3.C49 3 .0 2 7 3 .0 0 6 93 5 2 .9 6 5 2 . 944 ?• 924 2. P9£ 2. 872 2 . 84 7 2 .8 2 ? 2 .7 9 3 2 *774 ? • 780 2 .7 2 7 2 . 7 ''i 2 . 63 K 2 .6 5 9 2 . 677 2 .6 1 6 2 .5 9 5 2 .8 7 4 2 • c 54 2 . 534 2 . 509 2. 485 2 .4 6 1 2 .4 3 8 2 .4 1 5 2 .3 9 3 2 .371 2 . 349 2 . 328 4.0 3.0 15 4.5 3.5 2.5 PERIOD (second) 2 fl. 3 3 . 3.T. 4 2 . 4 6 , = J . 3 5 . * 2 . <3.5. Zl • 7 6 j ,92« 99 . 40 65 SEO v e rtic a l Component February 5 1966 9 8 .1 O Q .1 2 0 . 120 2 4 . 29 36 . 26. 31 38 . ? 8 . 32 3 9. 30 . 34 4 0 . 31 . 35 4 9 . 3 3. 36 4 1 . 3 4 . 37 a 1 • 3 5 . 38 4 2 . 3 5 . 38 41 . 3 6 . 38 *1 « 3 7 . 28 41 • -*6. 37 4 0 . 3 6 . 36 39. 3 5 . 35 38. 34 . 34 3 6. 3 3 . 32 35* 31 • 30 3 3. 2 9 . 28 31 . 2 7 . 26 2 9 . 25 • 24 2 7. 22 • 21 25* ?7 • 19 2 ? . 1 8 . 16 2 5 . 15* 1 4 1 8. 1 3 . 1 1 15. 1 1 . 1 3. 1 0* 7 1 1 . 4 9. 8 . 3 7. e . 2 6 . 8 . 3 6. 8. 4 6. 5 • 5 6. 6 7. 6. 7 a* 8 . 8 9. 8. 9 ,1 7. 16 11 • 7 . 1 1 1 2. 7 . 1 2 1 3. a • 1 3 1 4. 1 0 . 1 4 14. 12. 14 1 3* 1 4. 1 4 13 . 1 6 . 1 5 1 1 • 1 8. 15 10* 2 0 . 1 5 8 . 21 • 1 5 7, 2 3 . 1.5 7. 2 4 . 1 7 1 0 . 2 7 . 1 9 1 3. 2 9 . 22 1 8. 3 3. 26 23. 3 7 . 31 2 9 . 41 . 36 35. 4 5 . 41 4 0 . 4 9 . 47 46 . 5 3 . 52 51 . 5 7 . 57 5 7 . 6 0 . 61 61 . 64 • 65 6 5 . 6 6 . 63 69 . 6 8 . 7 1 71 . 70 . 72 73. 76* 73 T4. 70 • 73 74. 6 9 . 71 72. 6 6 . 67 68 . 6 2 . 62 6 2 . 57 . 55 55. 52. 47 4 6. 4 5 . 38 36 . 4 0 . 29 25 . 36. 20 1 5. 3 4 . 1 7 11. 37 . 22 20 * 4 2 . 32 32. 44 44 . 58 . 55 56. 6 7 . 66 67. 7 6 . 76 77. 8 4 . 95 86. 92 . 9 3 94 . 9 8 . 98 93. 1 0 0 . 0 0 10 9. 99 • 98 98 . 9 4. 93 94. 87 . 85 36. 77. 75 7 6 . 65 . 63 6 5 . 5 2 . 50 54. 40 • 3 8 4 P. PERIOD (second) 11. 12. 13. 15. IB . 2?. 23. 2H. 23. 3<3. 42. 46. 50. 35. 62. *6o 71. 76. S2. 39. 9 f . l r'6.12 o © GO 4.C5R 4 .0 3 6 4 0 3.97 3 3 .9 5 2 3.932 3.912 3. 891 3. 862 3. < 3 3 3 3.83 4 3. 775 3. 747 3. 720 .693 » 666 . 640 3. 614 3.538 3. 553 3.538 i: 2 a i 3.5 3. 465 442 _V^ 3.419 3. 396 — - 3. 373 3. 351 3. 329 3.397 *S— 3. 296 3.264 K 3. 244 3.223 -1. 203 . 1 32 .156 . 1 30 O LU C L cr O ° 30 3.055 3.031 1 : % % 1 3-0 2. 960- 2. 937 2. 91 5 2. 993 2. 071 2.94 5 2. 32 3 2. 3^7 2.787 2. 767 2. 742 2. Tl ** 2. 693 2.670 2 • 54 6 2. 624 2. 601 2.579 2. 550 2. 536 2.515 O C 2.4 95 ^ . O 475 2 .451 ’ •4 2 7 2. 40 4 2. 30? . 295 . ? 7 5 . 255 .231 . 20 9 . lfl? . 1 65 . 1 * 3 ► 122 »l r* 2 29. 31 . 24. 14. 35. 73. 94. 1 OO • 90 • 71 • HKC vertical component January 2 0 1967 298 12. 13 . 1 5 . 18. 4 . 675 4 • 651 4 .6 2 6 4 . 602 4. 578 4 • 554 4 . 531 4 .5 0 8 /\ C 4 .4 8 5 *-T.Zj 4. 462 4. 440 4 ,4 1 7 4 .3 95 _ 4 .3 7 4 “ 4 .3 5 2 0 4.3 3 1 4 .3 1 0 0 4 .2 8 9 4 .2 6 8 {ft 4 .2 4 7 W 4 .2 2 7 4 .2 0 7 N 4 .1 8 0 E 4 . 154 4 .1 2 8 4 . 102 4. 077 W 4 .0 5 2 —* - 4 .0 2 7 . _ - - 4 .0 0 3 LL O *1-0 TO > H O o _ _ l uu > CL 3 o DC o 979 955 3 .9 3 2 3. 908 3. 885 3 . 863 3. 840 3 .8 1 8 3. 796 3 . 775 3. 753 3 .7 3 2 3 .711 3 .6 9 0 3 . 670 3. 650 3 . 630 3 . 605 3 .5 9 0 3. 556 3. 533 3. 509 3. 486 3. 463 3.441 3 .4 1 8 3 .3 9 7 3 . 375 3. 353 3 . 332 3 .3 1 2 3.29 1 3 .27 1 3 . 250 3. 227 3. 20 3 3 . 1 80 3 . 1 57 3 . 1 3 5 3 .1 1 3 3 .09 1 3 .0 7 0 3 .0 4 8 3 .0 2 7 3 .0 0 7 2 . 986 2. 966 2 . 943 2.9 2 1 2. 898 2. 876 2. 955 2 .8 3 3 2 .8 1 2 2. 791 2. 7 71 2.7 5 1 2 . 728 2 .7 0 6 2 .6 8 4 2. 662 2 . 641 3.5 15 PERIOD (second) 2 5 . 2B . 3 3 . 39 . * 2 . 4 6 . SO. 55 . 6 2 . 6 6 . 7 1 . 76 . 8 2 . 89 . 9 8 .1 0 8 .1 2 0 65 40 5. 2. 4. 4 5 6 7 1 0 7. 5. 2 • 2. 4. 5. 5 . 6 • 3. 5. 4 6 7 8 1 1 8 • 5. 2. 5. 4. 5. 6. 4. 7. 5 7 8 9 1 2 9. 5. 2. 5. 4. 5 • 7. 5. 8. 5 8 9 1 0 1 3 9. 6. 2. 5. 4. 5 • 7 • 6. 9. 6 9 10 10 1 4 10 • 6. 3. 5. 4. 5. 7. 7. 10. 6 10 10 1 1 1 5 11 • 7. 3. 5. 3. 4. 6 • 3. 11. 2 7 10 1 1 1 1 1 6 11. 7. 2 • 3. 5. 3. 4. 5. 9* 12. 7 11 12 12 16 12. 8. 3 • 3 • 5. 2. 4. 4. 10. 12. 2 7 11 12 12 1 6 13. 8. 3# 4. 5. 1 • 4. 4. 11. 13. 7 11 12 11 1 7 13. 9. 4. 4. 6. 1 • 4. 5. 1 1 • 13. 7 11 12 11 1 7 14. 9. 4 • 5. 6. 1 • 4 • 7. 1 2. 13. 7 10 12 1 0 1 7 14. 10. 5 • 5. 6. 1 • 4 . 9. 12. 1 3. 6 10 1 2 1 0 1 6 14. 11. 6. 6. 6. 2. 5. 11. 11. 1 3. 6 9 11 9 1 6 14. 11. 6. 6. 7. 3. 6. 12. 11. 12. 6 8 1 1 8 1 6 14. 12. 7. 6. 7. 4. 7. 1 3. 10. 12. 5 7 10 7 1 5 14. 12. 8. 7. 7. 5. 8. 1 3. 9. 12. 5 6 9 6 15 14. 12. 8. 7. 8. 6. 8. 12. 7. 11. 5 5 8 6 1 4 14. 12. 8. 7. 8. 7. 9. 1 1 • 5. 11 • 5 4 7 5 I 4 13. 1 2. 9. 8. 8. 8. 10. 9. 4. 11. 5 4 6 5 1 3 1 2. 12. 9. R. 9. 9. 1 1 • 8 . 2. 11. » 5 4 5 5 13 12. 12. 9. 8. 9. 10. 1 2. 7. 2. 11. 5 4 4 6 1 3 1 1 • 12. 9. a. 9. 1 1 • 1 3. 6. 2 . 11. 5 4 3 7 1 3 9. 11. 9. 8. 9. 11. 1 4. 7. 4 . 11. 3 5 4 2 7 I 3 8. 11 • 9. 7. 9. 12. 1 5. a. 6. 10. 5 4 1 8 1 3 6. 10. 9. 7. 8. 12. 15. 10. 7. 10 • ■ 5 4 1 9 1 2 5. 1 0. 8. 6. 8. 12. 16. l i . 8. 9. 5 4 2 9 1 2 3. 9. a. 5. 7. 12. 16. i i . 9. 8. 5 4 3 10 1 2 3. 9. 8. 4. 6. 12. 16. i i . 9. 6. • 4 3 4 10 1 2 3. 9. 8. 4. 6. 11. 15. 10. 9. 5. 3 3 5 1 0 1 1 4. 8. 7. 3. 6. 10. 15. 8. 9. 6. 3 2 6 1 0 1 1 4. 8. 7. 3. 5. 8. 1 5. 6. 9. 7. 2 0 6 1 0 1 0 5. 8. 7. 4. 6. 6 . 1 4. 4. 9. 8. 2 1 7 1 0 9 5. 8. 7. 5. 6. 4. 14. 3. 9. 10. 3 3 7 9 8 6. 8. 7. 6. 7. 2. 15. 1 • 10. 11. 3 5 7 9 7 6. 7. 7. 7. 8. 3 . 1 7. 1 • 10* 12. 4 6 8 8 6 6. 7. 7. 8. 1 0. 7. 19. 3. 11. 12. 4 8 7 8 5 5. 7. 7. 9. 12. 11. 22. 5. 12. 12. 5 9 7 7 4 5. 6. 6. 11. 1 5. 1 5. 2 6. 9. 12. 1 2. 5 1 0 7 6 3 4. 6. 6. 1 2. 1 8. 21 • 30. 13. 1 2. 1 0. 6 1 1 6 6 2 3. 5. 6. 14. 22. 26. 34. 1 6. 12. 9. 7 12 6 6 3 3. 5. 5. 1 7. 27. 32. 39. 1 9. 1 1 . 7. 7 1 2 5 5 4 3. 4 . 6. 1 9. 32. 38. 44. 2 1. 10. 5. 8 1 2 5 5 5 3. 5. 7. 2 3. 38. 45. 4 9 . 22 • 9* 4 . 8 1 2 5 5 6 5. 6. 9. 26. 4 4 . 51 • 54 • 22. 8. 5. 8 1 1 6 6 7 6. 9. 12. 31 • 51 • 57. J5 8t . 23 • 7. 7. 8 1 1 6 6 9 9. 1 2. 1 6. 35. 5 flryro 3 . 62 • 24. 8 . 8. 8 1 0 7 6 1 1 1 2 • 16. 21 • 4 1. 68. 65. 2 7. 8. 10. 7 9 7 7 1 3 17. 22 . 28. 4Ry'7 3 . 73. 6 8 . 3 0 . 8. i o . 7 a 7 7 1 5 22. 30 . 36. /6 lY 70.. ^ 7 0 67 63 60* 56 r 56 52 / 52 45 46 40 44 39 38 30 24 I ? 22 34 30 26 17 1 2 8 1 6 1 2 9 22 I 9 16 6 6 7 6 1 4 I 3 1 0 1 0 I 4 1 2 1 3 1 8 1 0 1 6 24 6 21 34 15 24 31 39 47 55 47 61 58 70 72 82 86 96 90 98 96 100 99 100 100 99 99 95 91 83 87 79 79 69 74 64 69 58 60 50 43 38 3 3 26 I 9 20 SEO v e rtic a l com ponent F e b ru a ry 7 1966 120 2 9 9 PERIOD (second) 11. 12. 13. lb . 18. 2 2. 26. 2 * 8 • 33. 39. 42. 46. 5 0. &•». 62. 6ft. 71. re . M2. 3'?. O H . 1 0 j » . 1 2 f>. >" [ — o o L L 1 a. go O 4. 3 66 4 . 33ft 4.307 4. 2 7 < 3 4. 251 4.22 3 4. nb 4 . 16* 4.141 4.115 4 t 0H4 4 . 063 4 .0 3 7 4.012 3.<Jft8 2.063 3 .030 3. Ot 5 3.801 3.868 3.646 3 .822 3. 7 ‘ 3. 777 3 • 755 3 . 73 3 3.712 3.601 3.6 70 3 . 640 3 . 628 3 • 608 3 .588 2 • 562 3.535 3 .6 10 3.4 85 3 . 460 3.435 3.411 3.387 3 . 364 3. 341 3.318 3.205 3 • 273 3.251 3.2 30 3. 208 3.1P7 3 . 1 66 3.146 3. 1 26 3.101 3.076 3 • 052 .1. 028 3 • 005 2.082 2.959 2 .936 2.514 2 .89J 2.871 2.650 2. 629 2 . 609 2 .760 2 . 765 2.741 2.718 2 .695 5 .6 73 4.0 2 .* 2 .62 9 2.603 2.587 2. 5ft 7 2 . 646 2. 62 3 2.500 2 .478 2 .456 434 2. 3.5 30 2.5 2.392 2. 372 2.351 2. 3 29 2 .30 7 2.235 2 . 263 2. 242 2 .222 2 . 202 2 • 1 79- 2 .1 57 2.1 16 2.115 HKC E -W component January 16 1 9 6 7 < 3 8 . 9.3 • 94 • 9 6. 96 . 9 4 . 44. 44. 96. 9H CC. 99. 99, 9'-*. y t. S9. 98. 98. 98. 99.100 98.100. 100.100.10 0,100.10 0. 100. TOO.I 0 0*10 0 s S 2 • 97. 97. 97. 97. 98. 99. 09. 100.10 3. 9 9 1 . 91. 41. 0 2. 96. 77. 98. 98. 97 TT^<<T-r-^^:— — r » < . > i. 7? . 04 . 94. <4 :STA RAf V COMP 2 f42 . ;DATETnngQ.lU7 1 :T. 1 5 - 100 GRND MOT ^£L M B jb . u -IJ j f f i l , L l y l ^ i y S T A HKC C OMP z c-n ---- .------ .-----.-----— ----- ■ -----. --- J ||U » - IU - i »A^DATE Ta.n. la _iqfe7 rfcgTJpJ ' . ■ — 86 GROUP VELOCITY (km/sec) PERIOD (second) . 0 8 3 » * * * 1 ^ 4 7 ► 626 » . c P'S .556 3.5 3 • 300 3 • 2 P 3 1. ?S« 3.2 3* 3 .219 3 • 1 62 3. I 3 0 3 .1 1 6 3. 6 04 3. ? 71 f;H 3.0 2 .0 3 6 2. 065 2 . 945 2. 925 2. 309 2.P73 2. 647 2. 622 2.793 2. 774 2. 75C 2. 727 2.7 04 2.64 1 2.659 2. 63 7 2.616 2 .CQ 5 2. 574 2. 553 1:13325 2.486 2.460 2 • a 37 2.414 2.39? 2.3 7? 2.348 2. 327 2. 3<"6 2. 286 2.265 2 .2 «2 2.214 2. 1 96 2. 1 73 2. I 52 2 . 1 30 2 . 1 0Q SEO ve rtic a l component February 13 1966 9ft, 9 5 . 9 8 . 10C. 100 . 9 8 . 94. o r . 302 11* 12. 1 3. 1 5. 1 8 . 22. 25 4 . 666 4 * 6 4 3 4.620 4 . 597 4 . 574 4.551* 4 . 529 4 .5 0 7 4 . 4854.5 4 . 442 4.421 4 . 400 4 V J 7 9 4 . 358 4 . 338 4 . 31 8 4 .2 9 7 4 . 268 4 . 238 4. 209 4.181 4 . 153 4 . 1 25 4 . 098 4 .0 7 0 > 044 3^4.0 0 3 .9 5 5 3.940 m 3 - 9 1 5 Q ) 3. 891 7 1 3 . 8 5 6 Q j 3 .8 4 2 12.5 1 5 PERIOD ► 3 3 . 39. 42. a O 13.0 "90. 51^ ,9 9. 7 Q + J53 • 31 •' 59T 16. 7 J 32m f 16. 38 J 164 <30. 51 J 6. j 36* 65 f 8. 40. 72 I 1 6. ^40. 69k 11. 25> SJm 1 3* 23 A 19. 25. 1 31 1 8. 20. 7. 1 6. 9. 20. 25* 28. 37. 41 • 59. 51 • 39. 64. 48. 28. 45. 3C • 30. 30. 15. 30. 30. 28. 1 7. 8. 32. 7. 1 4. 43. 1 5. 36. 6 0 . 19. 61. 61 • 30 • 72. 44. 43* 63. 43. 23. 33. 44. 10. 9. 30. 8. 13. 17. 2. 4. 5. - W - 1 * 0. 0. 0 . 0. 0. 0. o. 0. o. 0. 0. 0. 0. 0. 0. 0. 0. 0. (second) 4 6. 5 0 . 5 5. 62. 6 6. 6 5 8 2 . 89. 9 8 .1 0 8 .1 2 0 . 120 o . 4 . 3. 3. 5 6 7. 7. 8 . 6 . 4 . 3. 3 . 5 7 8 . 8 . 9 . 6 . 4 . 4 . 3 . 5 8 9 . 9 . 10. 5 . 4. 4. 3. 5 9 1 0. io . 1C. 4 . 4. 3. 3 . 5 10 11. 11. 1 0 . 2 • 4 . 3 . 2 . 6 1 1 1 2 . 11. 9 . 1 • 4 . 3. 1 • 6 12 1 3. 11. 8 . 3 . 4 . 3. 1 • 6 1 3 1 3. 11. 7 . 6 . 4 . 3. 1 • 7 1 5 1 4 . 11 • 6 . 8 . 4 . 3 . 3. 9 16 1 5. 11. 6 . 1 1. 3. 3. 4 . 1 1 1 7 1 6. 12. 7 . 1 3. 3. 3. 6. 13 1 9 1 7. 13. 8 . 15. 2 . 4. 8 . 1 6 21 1 9. 1 5. 9 . 1 7. 1 . 5 . 1 o . 18 23 2 0. 16. 11. 1 8 . 3 . 6. 1 2 . 21 25 22. 1 7. 1 1. 20 . 5 . 8 . 1 5 . 25 27 2 3. 1 8. 1 2. 22 • 3. 10. 1 8 . 28 29 2 5. 19. 12. 2 3 . 1 1. 13. 21 • 31 31 2 6. 1 9 . 1 3. 2 5 . 1 5 . 17. 2 5. 35 34 28. 20. 1 3 . 2 5 . 1 8. 2C • 29. 39 36 29. 21 • 14. 2 4. 1 9 . 23. 3 2 . 42 37 30. 22. 1 5. 2 1 . 1 9 . 2 4. 3 4 . 44 38 3 0. 2 2. 1 5 . 1 6. 1 7. 23. 3 4. 45 37 2 9. 21 • 1 5. 10. 14. 22. 3 4 . 44 36 2 8. 20. 13. 5 . 1 1 . 20. 3 3 . 42 33 2 6. 1 8 . 12. 2 . 6 . 18. 31 • 39 30 23. 1 7 . 1 o. 1 • 6 . 16. 2 8 . 36 27 21 • 1 5. 1 0. 2. 6 . 1 5. 2 6 . 32 23 1 8. 1 3. 9 . 5 • 7. 14. 2 3. 28 19 1 5. 11. 9 . 7 . 8 . 13. 21 • 24 15 11. 9 . 8 . 8 . 8 . 12. 1 8 . 20 12 8. 6 . 7 . 6 . 7 . 11. 1 6. 1 7 9 5. 3 . 5. 4 . 6 . 10. 1 4. 1 4 7 4. 1 • 5 . 1 • 5. 9. 1 3. 1 1 6 4. 2 . 5 . 3 . 4. 8. 1 1. 9 5 5. 4. 6. 6 . 3. 7 . 1 0. 7 5 6 . 6 . 8 . 9 • 3 . 7 . 9 . 6 5 8. 9 . 11. 1 2 . 5 . 8 . 9 . 6 6 10. 1 3 . 15. 1 7 . 7 . 8. 8 . 7 10 1 3. 1 7. 19. 2 1. 9 . 8 . 7 • 9 14 1 8. 21 • 2 3. 2 4 . 11. 7 . 5 . 1 1 1 9 2 3 .. -2TV 2 5 . 1 2 . 7. 3. 1 3 ^ 2S T 3 1. 31 • 2 5 . 1 3. 7 . 2 • 1 6 <*30 3 4. 36. 3 4 . 2 4. 1 3. 8 . 6 . 1 9> -^4TT. J 7 . 2 4 . 14. 9. 1 0. 2/C 4 5. 45. 2 3. 1 3. 11. 1 3 . 38 /4 8 5 1. 5 0 . 64V 2 2 . 10. 11. 17. P 55^-— 5 8 . 5 6 . 4 9 . 2 0 . 7 . 9. 1 9. (3 at /SO s&g. 52>. 1 8 . 3. 8 . 1 9. /#:i f 64 6 6. 6?V. 1 5. 1 • 7 . 1 9 ./ 67 6 8 y 5 3 . 1 1 . 4. 6 . 1 8 J >44 . 69 6 U soy 6 . 5 . 6 . 1 61 4 5 . 69 4 5 / 1 • 5 . 4. 14 L 4 5 . em r 6 4 / '5 4 . Afi 5 . 1 . 1 sU 47 J 4 9 ..*47 8 . 7. 7. 2 0 ./ 50 3 <^54. 32 9 . 1C. 13. j t L 53W W f 7 4 1^ '3 6 . 2 / 5 . 1 4. 2 0 . A 55. 5 6k rfe 0 T 9. "20 2 . 1 8. f \ • STM 14 /3 U > ^21 • 14 1 2. 21 • EOm A 6 . s i \3J 2*4. 1 5 . 1 1 2 0 . 2 3 . 133. /4 9 . sJL / l 7. 9 . 9 2 5. 2 2. / 32 . / 51 . 427 11* 3 . 7 2 4 . 1 7 . / 30. 5 2 . f f 5 ' 10. 2 . 6 — • 4 6 . 51 • 52. H e 1 5 . 12. 4 . lr!> 8 . 1 2 . 1 6. 1 9. l e 1 5. 7 . 6 . 5 . 7 . 10. 35 1 7. 9. 5 . 2 . 2 . 4 . 49 2 0 . 11. 5 . 1. 1. 2. 56 2 2 . 11. 5 . 1 • 1 • 1. 54 2 1. 11. 4 . 1 • 1 • 2. 41 18. 10. 3 . 2 . 3. 3. 23 1 4. 9. 3 . 2 . 4 . 3. 9 11. 9 . 5 . 4 . 4 . 3. 6 9 . 10. 7 . 6 • 5 . 4. 13 1 0. 1 0. 8. 6 . 5. 4. 23 1 1 . 8 . 7 . 5 . 3. 3. 26 9. 6 . 4 . 4 . 1 • 1 • 22 6 . 3 . 2 . 3. 0 . 1 • 1 8 4 . 3. 2 • 4 . 2 . 2. 20 7 . 6 . 5 . -5. 2 . 1 • 30 1 4. 1C. 8 . 6 . 3. 2. 41 1 9 . 12 . 9 . 7 . 5. 4. 47 19. 10. 8 . 6 . 3. 3. 4 4 1 2 . 5 . 5 . 4 . 1 . 2. 32 9 . 1 • 4 . 3. 1 • 1. 16 1 1. 5 . 4 . 3 . 2. 1. 1 8 11. 5. 3 . 3. 2 . 1. 28 11. 5 . 0 • 3 . 3 . 3 . 25 1 0. 5 . 3 . 4 . 4 . 3. 1 4 7. 5 . 4 . 4 . 5 . 4. 5 3. 3. 3 . 3. 4 . 4. 0 o l Om o l 0 . 11 l l 0 0 . 0 . 0. 0. 0 . 1. 0 0 . 0 . 0 . 0 . 0 . 1. 0 0 . 0 . 0 . o . o . 1. 0 0. 0 . 0 . 0 . 0. 1. 0 0 . 0 . 0 . 0 . 0 . 1. 9 . 12. 1 3. 1 5 1 8. 2 0 . 2 3 . 26. 2 9. 31 • 10. 1 2* 1 3 . 1 5 18. 2 0 . 2 3. 26. 2 8 . 31. 10. 1 2 . 1 3. 1 5 18. 20. 23# 2 5 . 2 8 . 30. 10. 11. 1 3. 1 5 17. 2 0. 2 2. 25. 27. 30. 9. 11. 1 2. 1 5 1 7. 1 9 . 2 2. 24. 2 7 . 2 9. 8 . 1 0. 1 1«~ 14 16. 1 9 . 2 1 . 24. 2 6. 28* 6 . 8. 10. 13 1 5. 1 8 . 2 0 . 23. 25. 2 8. 4 . 7. 1 0 . 1 2 1 5. 1 7 . 1 9. 22. 2 4 . 2 7. 2 . 6. 9. 1 1 1 4 . 1 6 . 18. 21. 2 3. 2 6. o . 5 . S * 10 1 3 . 4 5 . 1 7 . 2 0 . 2 2 . 25. 2 . 5. 7. 9 1 2 . 1 4. 16. 1 9. 21 • 24. 4 . 5. 7 . 9 1 0 . 1 3. 15. 1 7. 2 0. 23. 6 . 6. 6. 8 9. 11. 1 4. -1 2 . 1 6. 19. 22. 7 . 5. 5. 6 7 . 9 . 11. 1 4. 1 71 20. 7. 4 . 4. 5 6 . 8 . 10. 1 3 . 1 6. 19. 7 . 3. 3 . 3 5. 7. 9 . 1 2. 1 5. 1 6. 7. 2. 1 • 2 4 . 6 . 9 . 11. 14. 18. 7 . 2. 1 • 2 4. 6. 3. 11. 14. 17. 8 . 4 . 3. 4 5. 6 . 6 . 1 0 . 1 3. 16. 9. 6 . 5. 5 6. 7 . 8 . 1 0. 1 3 . 1 5. 1-G.— 7 . 6 . — 6 . 7 . 9 . ID . 1 2 . IS . 9 . 6 . 6 . 6 7. 8 . 9. 11. 12. 14. 8. 5. 5. 6 7. 8. 9 . 11. 1 2 . 1 4. 6 . 3. 4 . 5 7. 8 . 9. 11. 12. 1 4. 5 . 1 • 3 . 5 7 . 8 . 9 . 1 1 . * 1 2 . 14. 5 . 2. 3 . 5 7. 8 . 9. 1 0 . 12. 1 4. 6 . 4 . 4 . 5 7. 3. 9 . 10. 12. 1 4. 7 . 5 . 5. 6 6. 7. 3. 10. 12. 14. 7 . 6 . 6 . 6 6* 6 . B e 9 . 1 2 . 1 4 . 7 . 6 . 6 . 5 5. 6. 7 . • 9 . 1 2 . 14. 7 . 6. 5. 3 3 . 5. 7. 10. 1 2. 1 5 . 6 . 5 . 3. 1 2 . 5 . 3 . 10. 13. 1 5. 7 . 5 . 3. 2 4 . 6 . 9 . 11. 1 4. 16. 8 . 6. 5. 5 6 . 3. 10. 12. 1 5. 1 7. 1 0. 9 . 9 . 9 9. 1 1 . 12. 14. 1 5. 1 8. 1 3. 1 3. 12. 1 2 1 2. 1 3. 1 4. 15. 1 6. 1 8 . 16. 16. 1 S. 15 1 4. 1 4 . 1 5 . 1 6. 1 7. 1 9 . 2 0. 19. 1 8 . 17 1 6 . 1 6 . -15. 16. 1 8. 20. 2 3. 21. 1 9. 1 7 1 6 . 1 5. 15. 1 6 . 1 8. 20. 21 . 1 9. 16 1 4. 1 4 . 14. 16. 1 8. 21 • 2 7 V 21 . 1 7 . 1 3 1 1. 1 1 . 1 3 . 16. 1 8 . 21. 2 9 . 19. 1 4. 10 7. 9 . 12. 15. 19. 22. 30. U e . 12. 6 3. 7 . 1 1 • 15. 1 9. 22. 31. \ 9 . 12. 6 3. 7 . 12. 1 6 . 2 0. 2 3. gyl. -1 5. 11 9 . 1 O. 1 4. 1 7. 2 0 . 2 3 . 2ojv r r * 1 5. 1 5. 1 8 . 16. 1 3 . 1 9. 20 • 21. 22 • 24. 25. 30. 26.V 22*" 2 0 . 1 9. 21 • 23. 25. J ± & m <29. 2 5V 22 2©5l 2 1. 2 3. 26. 3 6 . . i'-" 1 8 1 8. 1 8. ^2 3. 26. 30V 1 7 . 1 3 . 1 2 1 3 . 1 5. 1 8 . 2C? 26. 11. 6 . 5 8 . 1 2 . 16. 19. 2 3 ^ A 3 . 11. ■6. 3 6 * ID . 4 6 . 4 9 . 2 3 . 22. 1 3. 1 0. 8 S. 1 1 . 1 4. 1 8 . 23. 27. 1 9. 1 4. 13. 11. 1 2. 10. 11 1 1 11. 1 2. 1 3. 1 4. 15. 17. 1 9. 20. 2 3. 2 *V /2 9 . 9. 5 . 7 . 9 1 2. 1 5. 1 8 . 22. dkffm 31. 6 . 1 • - 6 . 9 13. 1 6. 2 0 . 2 4 . E fim 32. 8. 6 . 7. 1 0 1 4. 1 8 . 22. 30 . 34. 9. 10. 11. 1 3 16. 2 0 . 2 4 y 281 32. 36. 9. 12. 14. 1 6 1 9. 2 2 ./"2 fS m 30. 3 4. 3 8. 9 . 12. 1 5 . 1 7 2 0. 2 8 . 32. 3 6 . 4 0 . 7. 11. 1 4. 1 8 21 • 2 9 . 33. 37. 4 2 . 5. 10. 14. 1 8 22. f 26 • 30. 34. 39. 44. 4 . 9. 14. 18 2 3. 2 7. 31 • 3 5. 39. 4 5. 4 . 1 1 . 1 5 . 1 9 t2 6 . 3 0 . 3 4 . 4 0 . 4 7 . 8 . 1 4 . 1 7 . 20 22. 29. 34. 4 1. 49. 1 3. 1 7. 1 8. 1 8 19. 2 2. 2 7 . 34. 43. 53* 1 8. 1 7. 1 6. 1 4 1 4. 1 9. J 2 7. 37. 47. 57. 2 2 . 1 5 . J 9 . 8 . 15. 2 1 7 1C. -2 1 / 3 2 . 44 • 61 • 4 3 . 5 5. 5 4. 64. 75. 6 4 . 7 3. 81. 44. - 4 6 . ^3 6. iB . 53 . 68. 6 7. 64. 64 e 66 6 9 . 7 3 . 7 7 . 82. 85. 9 0. 8 8 . 9 6. 47*- 67V- 88.- -8 9. 9 1 . 9 3 . 9 4 . 9 6 . 9 7. 9 8. 98 99. 9 9 . 99. 00. 100. 100. 78. 8 2 . 84. 86 89. 91 . 9 3. 9 5 . 9 6. 9 7. 5 4. 56. 61. 66 71. 7 6 . 61 • 85. 88. 91 • 3 0. 3 2 . 3 6 . 4 2 5 0 . 5 7 . 6 5 . 7 2 . 7 8 . 83* '1 6 . 1 1T“ T 4 . ~2T" N jO i 3 9. 4 9 . 58. 6 7. 74. 1 2. 6. 2. 7 1 ^ . 26. 36. 4 6. 56. 6 5. 1 1. 11. 10. 10 1 3. 2 8 . 3 7. 4 7 . 57. 7 . 1 1 . 1 2 . 14 1 6 . 1 9 V 2 5 . 32. 4 1 . 50* 3 . 9 . 1 2. 1 5 1 7. 20. 24. 30. 37. 45. 4 . 8. 11. 14 1 6. 2 1. 25. 29. 3 5. 42. 5 . 8. 10. 13 17. 2 i . j 25. 29. 3 4. 4 0. 4 . 8 . 1C* 1 3 1-7. 2 1.1 2 6 . 29. 34. 3 9. 3 . 7. 10. 1 3 17. 2 1. (2 5 . 29. 33. 3 8. 5 . 9. 11. 1 4 1 7. 2 0 . 124. 28. 32. 37. 7 . 9 . 11. 1 4 1 6. 20. 2 7 . 3 1. 36. 5. 8 . IO . 1 2 1 5* IS . 22V 26. 30* 35* 2. 5 . 7. 10 1 3. 1 7 . 21 . 25. 29. 34. 2. 4 . 6 . 9 1 2. 1 6. 2 0 . 125. 2 9. 34. 3. 6 . 8. 1 1 1 4. 1 7 . 21 • |25. 30. 34. S . 8 . 1 4 . 13 1 6 . 1 9 . 22. \26. 3 0. 34. 6. 10. 1 3. 1 5 1 8. 2 1. 2 4 . 1 2 7. 3 0. 34. 7. 10. 1 2. 1 5 1 7. 20. 23. 126. 30. 33. 5. 8 . 10. 1 2 1 5. 1 8 . 21 • 2a . 2 8. 2 6.- 32. 2 . 4 . 5. 8 10. 1 4 . 1 7m 2?W 2 5. 30. 4 . 6 . 8 . 1 0 1 2. 1 4 . 1 7. 211 25. 30. 5. 7. 9. 1 1 1 3. 1 5 . 1 8 . 22*> 2 6. 31 • 4 . 6 . 8 . IO 1 3. 16. 2 0 . 24.,] 28. 33. 1 , 5 . 8. 1 1 1 4 . 1 8 . 22^- 31 • 35. 6 . 9 . 1 2 . 1 5 1 8. 21. 29. 3 4. 3 8. 9 . 12. 1 5. 1 8 21. 2 4 / '2 8 . 3 2. 3 6. 4 0 . 4. 9 . 1 2. 1 5 1 9. 29m 32. 37. 411 4 . 8 . 11. 14 1 8. 2 2. 2 6 . 31 . 3 6. 41 . 5. 8 . 11. 1 4 1 7. 21 • 2 5 . 3 0. 35. 4 0. a . 8. 1 7 . 21 • 2 0 . U 5 . 2 9. 2 9. 3 4 . 3 3. 3 9c 4 . i o l 13 17. 38. 4 . 8. 10. 13 1 6 . 2 0 . 24>v 28. 3 3. 37. ANP Vertical Component November 13,1965 303 ----1 GROUP VELOCITY (km/sec) PERIOD (second) . 33. ?Q. 42. 45. SO. 5b. t >2. ^ei. io a . 120 . 4 . 552 4 . 5 31 4 • :>ov 4 .4 SO 4.45-5 4 . 4 4 7 4 . 4 2 7 4 . 4 0 7 4 . 3 7 7 4. 3 47 4 . 3 1 3 4 . 2 or* 4 . ?r>i 4 . ? 1 3 3. 907 3.07 3' 3 . 3 . . 2 4 3. VOI 3.57 7 J..3S4 3-^31 3 . 500 7. r ; 7 7 . rt * ? 3.743 3 . 721 3 . 5 r 1 3 . ^ 4 S 3 .5 1 9 3 • 4 < * 4 3. 3Of 3 . J 7? 3 .3 4 ° 3 . 2 H I 3.2 59 3.^37 3.215 .3 . I 95 J. 1 74 3 . 154 3 . 1 .33 3 . IO? 3.0 54 3.060 3.0 16 3.012 P • 750 2. 726 P • 7 * )4 2 . 6 * 1 15 40 65 120 4.5 4.0 3.5 3.0 BAG vertical component; January 2 0 96" GROUP VELOCITY Ikm/sec) PERIOD (second) 11. 12. 13. 15. 18. 22. 25. 28. 3 3- 39. 42. 46. 50. 55. 62. 66. 71. 76. 82. 8 *. 08.108.120, 4 . 446 4.426 4 .406 4 . 376 4.346 4.3 17 4,288 4.260 4.232 4. 204 4.177 4 . I 50 4.124 4.097 4.072 4.046 0 2 1 4.0 3.996 3.971 3.947 2. 923 3 . 899 3 .876 3.852 3. 82 9 3, 807 3 .785 3.7 6 2 3.741 3.719 3. 69 8 3.6 77 3.656 3 . 635 3.615 3.595 3. 5 63 .542 3.516 3. 491 3. 466 3. 491 3.5 3.^41 3.4 1 7 2 . 393 3.3 6 9 3 .3 4 $ 3. 323 3 . 3 0 0 3. 278 3 .2 56 3 .2 34 3 .2 13 3 • 19 2 3.171 3. 160 3. 1 30 3.11 0 3 • 085 3.061 3.0 37 3.01 3 7 A 2 .9 9 0 V-J-W 2.967 2 .945 2 .9 2 3 2.901 2 . 8 79 2 . 85 8 2 .8 3 7 2. «M 7 2 .797 2 .7 7 7 2 • 753 2. 730 2. 707 2. 684 2 . 6 62 2. 64 1 2 .6 19 2 . 5 JS 2 .5 7 7 2 .5 5 7 2 .5 3 7 2 . 5 1 4 0 C 2.491 2 . 4 fs9 2 .44 7 2. 426 2. 405 2. 384 2 .3 £4 2.34 4 2 .321 2.2 9 9 2.2 7 7 2. 256 2. 235 2 .2 15 2 . 1 96 2. 1 73 2.151 2. 1 30 11. 13 11. 15 13. 18 15. 22 19. 26 23. 3 ! 29. 37 36. 43 4ti. 62, 67. 62 69. 71 80 . 8 1 89. 59, 95. 94. 98. 95. 100. 99, 9 7.1 00, 8 9. 96, 78. 88, 65. 79. 54. 69, 45. 60, 40. 51, 3 7. 41, 54. 5?, 63. 58, 50. 56, 47. 52. HKC v e r t i c a l component January i s 1 9 6 7 STA r H f , COMP 2 W _ f .OATF J ailJP+1 3 ‘ 7 0 9-3°°° J T ,v Tn O g GRNO VD T !dE . ;S TA CMC, CO M P *_____ :DATE_ni^:-ll_Li23_ht»l' 5 £ - ^ l :-1j|gg_GRND MOT. T r, i:j g f \ d Mcr;f2.. GROUP VELOCITY (km/sec) 4 . 0 .P 1 Q « 792 m 7 6f .7 4 ^ • 7 t e > • • 665 3 . 5 3 • ’ o? 3.371 3.3SO 3. 3 3<- 3.2 * 5 1 3 • 2 ? * 3 • 2 •** 1 ? .1 7 7 2 . 8 1 6 3.7Q 1 2 • 769 2.746 2 • 724 2 • 7 > 1 2 .6 8'j 2 . 5 CHG vertical component January 20 1967 1 6 . »1. 13. 15. 17. 19. 21. 23. 23 11. 13. 15. 17. 19. 22. 24. 26. 26 13. 15. 17. t<3. 2?. ?4. 26. 2 *. 29 15. 17. 2 0. 22. 24. ?6 . 29. 31. 31 17. Pi). 22. 24. 27. 29. 31. 33. 34 19. 22. 25. 27. 29. 31. 33. 35. 36 H . 25. 2 7. 3 9 . 32. 24. 36. ■ »«. 37 24. 27. 3 • 72. 3 5 . 3 # = ,. 38. 39. 39 26. 33. 33. ?5. 37. 39. 43. 41. 49 29. 33. 36. 39. 39. 41. 41. 42. 4? 32. 16. 38. 4 0. 42. 42. 41. 43. 40 15. 39. 41. 4 3. 44. 44. 44. 44. 40 JSm 41* 44. 4~. 45. 45. 45. 45. 3 9 40. 44. 46. 47. AJ. 4 5. 45. 45. 38 13. 4 6 . 4 >j. 48. 48. 45. 4 5 • 37 4 5. * r 0 > ^ 4 < ? . . 3 7 4 !i^ * rr. 52. 8 1 * ^ W r *~6 . 46. 46. 17 /5n« 5 2 . 5 4 5. h B ~ * 46. 37 fc?. > 4 8 . 4 4. 44. 47. 39 5 ? ./4 7 . 43. 44. 48. 4? r 4 ^ ^ 6 . 45. 40. 43. 4 9 ^ 4 5 5 6 . R^, 51? 43. 3 P • 41. • ITT *5*. 56. 55. 41. 35. a 0. f 52 . 5 4 5 * 5 6 . 5 5 ./ y v . 38. 31. 3 9*1 ^JT "6" 'T * 6 6 . 55J/45. 36. 26. 3 7. 166. 65 63\ 56. i>4/ 47, 33. 21 . 16. IHq. 79 5 l i 55. <$4./ 46. 39. 1 6 . 3 5 . 160 • 75 49.1 55. 6AJ*46. 2 7 . in . 35. /63. 79 4 7.1 «8 . 56\l 46. 76. ?. 36.J66. 3S~ 45.V55. ? e iX 7 . 28. 1 0 . 39.//70. 0 ■*4.}bO. 32. ?n. 43*✓ 74. /93 44 ./ 58. 62.N f4 \ 3 c. ?C. 4^V 77. [98 4 6 ./ 61. 65. 6^.V4J7. 4 lV ~a6« 81.(96 5 1 / 65. 7 0 . e S . ^ T v - J ii ^ 7. 8 4./9 5 7 C • 74. 72. 64 . 60. 70. 56./ 93 *-4. 78. 8 ' . 78. 72. 6 9 . 78. 88 / *9 72. 91. 8 *=. 84. 79. 77. 61. 8/ . (95 79. < = f ~ *^TTTa^.a _ 9 . H fe. 84. 8 fi^ 9 3 . 51 96^-91. 94. 93. »T9— S 5«^!T. 91. 7 7 -T?. 98. 97. 97. 09. Q 4*T 93. 92. 74 0 7 . 98. 9 0 . 9 9 . Qe, 9 7 o 96. 93. ^ 4 9 9.1 9 0 .1 0 0 .1 0 0 .lO ''. 99. 93. 95. 75 00.103. 99. 99.1f-O.10O. 99. 96. 79 99. 98a 9 7 . -5 8 . 99.100.10 0 . 98.18 4 75. 94. 96. 98.100. 99. 5 ^9 3'J.^09. 8 95. 98.190. 9 4 “ 84. 82. 52. 84. 9fc.l Oi). 98 74. 73. 73. 75® 8 ^. 0 . 9 7.1 Q Q 63. 62. 62. 6 6 . 71. 77. 847^9^_. 99 5?. 51. 52. 56. 6 1 ® 6 8 . ^6 . 3 5.^Sl^_ 42. 4.P. 46. 52. 59. 6 ^. 76. 88 32. ? t. 7 9 . 3 7 . 4 3 . 5 r,. 5 7 . 6 6 . 79 24. 22. 24. 23. 35. 4 j , 47. 55. 67 17. 15. 17. 22. 2?. 34. 3 Q . 44. 55 11. 9. 11. 16. 22. 27. 31. 33. 43 7. 7, 6. 1 0 . 15. ? 0 . 2 7 . 21 . 27 8 . 1. 7. 7. 12. 17. 19. 15. 17 K. 1. 2. 5 . 9 . 1 4 . 1 6 . 1 1 . 9 5. 2. 2. 3. 7. 12. 14. 9. 4 =0 7. 1 . 2 . 6 . 11. 13. 9. J F. 3. I . I . 5. 1C. 12. 8 . I 6 . 3. 2. 2 . 5. 9 . 1 1 . 7. 2 PERIOD (second) . 1 5 . I n . ?c.. 1 1 . I Q . 4 ? . 4.6. 1 , 1. -51. 4-4. ‘ 6 . 7 1 . 7 6 . =»?. 8 5 . 9 8 . 1 3 S . 1 2 0 . 1 5 25 40 65 120 307 GROUP VELOCITY (km/sec) PERIOD (second) 3 9 • 42* 46. 50* 3= > . 6,2 . 66. 71, 76. .39, 98. 10E>. 12 0. ^ 4.5 3 9'+ '367 31 ? 235, 2 3 j 1 69 1 3 4 . l i e 3 <56- ^f>2 03 9 015- 9 9 3 332 © 6 ? 339 31. 5 797 ’ 77 4.0 3.5 3 9 7 375. 354 3 3 2 l i t i ! « a 3.0 97. j 952: 932 31 1 ,391 .967 121 79© 776 754 CHG vertical component June 16 1973 f K _* 3 * 1 € « 3 5 . 5 N q6 . ^ N 61 . 04, 2 9. :>a. 51 * 64. 7^V 7 9. 82. 46. 60. 57J 6* . 741 76• ©2. 54. 59. 71. 7^4 79. 82. 5- . /T>^ /7l • 7c. /SO. 81. 63. 61. «f3*‘J 73. /ffTT^83. 84. 84. 51. 7.3. 7^. 22. 35. 86 . 36. 53. t >4. 75. 33. 37. B7. 07. 86. 66. 75. 83. 87. 86. 80. 54. ©6 . 74. 83. 87. 83. 3‘9. 51. *2 . 73. 32. 87. 88. 89. 46. 60. 71. 31. 07. PP. 9 u• 43. 6C. 71. 31. 87. 39. 9( • 5:;. c2. 73. H I. 38. 90. «1 • S 4 .166. 76. 35. 90. 91. 92. 53. 69. 79. 3b. 91. 91. 9P. 39. 69. 76. 36. 91. 92. 9?. f PS. 90. 91. 92. 83. 39. 91. 92. 3 3. 39. 91. 92. - 3 4. gp. 91. 92. 84. 90. 91. 0.3. 85. 9C. 92. 93. 65. 91• 93. 94. 8 6. 92. 9*.. 95. S3. 94. 95. 96. 3*. 95. 96. 97. 92. 06. 97. 37. 91. 90. 97. 93. 89. 95. 97. 9So 39. 95. 9 7 © p 9• 90. 97. 93. 93. 9?. 9 3. 99.1^9. 95.10C.1C0.1CO. 95. 99. 99. 9 9. 93. P3. 93. 94» 94. 95. 96. 07. 97. 9 5. 99. 90. 99a 100. I l f - . ICO. 99. GROUP VELOCITY (km/sec) PERIOD (second) 66. 71, ?*c P9. 95.X ■ 1 5 40 65 120 3 9 5 463 < = 1 7 792 7^7 745 7 I S -04 67 I 647 6 24 1 ao 1 6 A 1 7 7 1 1 6 7.21 6 77 6*6 e 2 3 6 ” 6 4 *5 463 44? 422 402 * 7 5 ’ 37 3 16 315 2°4 ? 7 4 25? 4 0 3.5 2.5 CHG v e rtic a l component January 18 1967 309 GROUP VELOCITY (km/sec) PERIOD (second) 71. 76. R2. *7. 98.* 1 rtfl.l 2/*. 4.141 4.114 4.rR7 4 .Ofifl 4 . 7 4 A. r 08 3.933 3.957 3.933 3.904 3. 684 3. 836 3. P 1 3 3.7 9-. 3. 767 3.744 3 • 7 2 2 3. 7 * 0 3.678 3.057 3.636 3.5: 74 3.«53 3.53 3 6.5^ 7 3. 4^1 3. 4 55 3 .4 ^ 3 .405 3. 3 81 3.356 3.333 3 • 3 O 9 3.2 66 3.263 3. 241 3.21 0 3.196 3.175 3. 1 54 3.1 33 3.H 3 3.092 3.072 3.047 3 • 0 ? 3 2.999 2. 975 2.952 2.929 2.9-- 6 2. 684 2.062 2.041 2.020 2 .799 2.773 2.758 2 . 7 ’’ P 2.714 2.691 2. 668 2. 645 2.6 23 2. 601 2.5 80 2.5 59 2 .538 2.51P. 2.490 2 .475 2. 4 ? 2 2.4 30 2 • Aog 2.387 8 . 366 2.345 2. 325 2 • "*C 2 2. 206 2.258 2.236 2.215 2. 1 95 2. 1 74 2.152 2. 1 30 2.109 15 40 65 120 4.0 3.5 3.0 2.5 LAH vertical component March 7 1966 310 Table 1. Group velocities interpreted from the two — dimensional plots # LAH COMP 4, February 5> 1966 Period Velocity Period Velocity Period Velocity 81 3.626 45 3.060 22 2.769 75 3.590 4l 2.934 18 2.743 70 3.572 38 2.875 15 2.671 66 3-572 32 2.830 13 2.17 62 3-554 28 2.881 55 3.434 24 2.813 NDI COMP 4, February 3 > 1966 Period Velocity Period Velocity Period Velocity 120 3.770 62 3.642 24 2.983 107 3.792 55 3-642 22 2.793 97 3.792 49 3.642 18 2.778 89 3.748 45 3-621 15 2. 823 81 3.726 41 3.601 13 2.778 75 3.683 38 3.581 11 2.793 70 3.662 32 3.291 10 2.835 66 3.642 28 3.061 NDX COMP 4, September 28 , 1966 Period Velocity Period Velocity Period Velocity 120 3-640 66 3.617 32 3.009 107 3-664 62 3.571 28 2.787 97 3.688 55 3-493 24 2.733 89 3.664 49 3.472 22 2.676 81 3.664 45 3. 440 18 2.626 75 3.664 4l 3.368 15 2.638 70 3.640 38 3.242 13 2.746 11 2.794 10 2.871 311 Table 1# Group velocities interpreted from the two- dimensional plots (continued) CHG COMP k, June 15» 1971 Period Velocity Period Velocity Period Veloci 107 3.473 55 3.292 22 2.765 97 3.450 49 3.211 18 2. 700 89 3.450 45 3.128 15 2.620 81 3.458 41 3.079 13 2.630 75 3.473 38 3.073 11 2.640 70 3.450 32 2.930 IO 2.809 66 3.420 28 2.835 62 3.384 24 2.794 312 Table 2. Group velocities interpreted Prom the two — dimensional plots • LAH COMP 4 , August 30, 1967 Period Velocity Period Velocity Period Velocity 120 3.439 62 3.03^ 24 2.640 107 3.468 55 3.990 22 2.770 97 3.468 49 2.927 18 2.913 89 3.468 2.866 15 2.012 81 3.439 4l 2. 8l4 13 3.H7 75 3.411 38 2.692 11 2.900 70 3.274 32 2. 623 10 2.913 66 3.149 28 2.601 LAH COMP 4, September 28 , 1966 Period Velocity Period Velocity Period Velocity 120 3-575 62 3.087 24 2.693 107 3.555 55 3.042 22 2. 602 97 3.525 49 2.978 18 2.583 89 3.^39 45 2.916 15 2.5^2 82 3.357 4l 2 . 863 13 2.458 75 3.325 38 2.812 11 2. 562 70 3.204 32 2.763 10 2.610 66 3.180 28 2.72 2 ANP COMP 4, February 13 , 1966 Period Velocity Period Velocity Period Velocity 120 3.710 62 3.623 24 3.060 107 3.651 55 3.680 22 3.001 97 3.623 h9 3.651 18 2. 872 89 3.593 45 3.595 15 2.837 81 3.540 4l 3.46o 13 2.917 75 3.513 38 3.288 11 2.963 70 3.513 32 3.198 10 2.944 66 3.567 28 3.101 313 Table 2. Group velocities interpreted from tbe two- dimensional plots (continued) ANP COMP 4, February 7, 1966 Period Velocity Period Velocity Period Velocity 55 3.430 32 3.210 15 2.849 49 3.425 28 3.124 13 2.739 45 3.463 24 3.090 11 2.662 4l 3.425 22 2.985 io 2.624 38 3.353 18 2.871 Table 3. Group velocities interpreted Prom tbe two — dimensional plots. ANP COMP 5, February 5* 1966 Period Velocity Period Velocity Period Velocity 107 4.026 62 3.981 24 3.401 97 4.070 55 3. 964 22 3.353 89 4.051 49 3.931 18 3.283 81 4.016 45 3.866 15 3.183 75 3.921 4l 3.787 13 3.183 70 3.981 38 3.697 11 3.152 66 3.981 32 3.543 IO 2.945 28 3.451 ANP COMP 5, February 13, 1966 Period Velocity Period Velocity Period Velocity 107 4.069 55 3.981 22 3.397 97 4.069 49 3.930 18 3.360 89 4.069 45 3.881 15 3.313 81 4.069 41 3.817 13 3.301 75 4.053 38 3.755 11 3.301 70 4.033 32 3. 608 10 3.324 66 4.033 28 3.486 62 4.016 24 3.422 NDI COMP 5, September 28 , 1966 Period Velocity Period Velocity Period Velocity 120 3.826 55 3.670 22 3.051 107 3.846 49 3.644 18 2.929 97 3 • 8 46 45 3.510 15 2.831 89 3.819 4l 3.315 13 2.776 81 3.794 38 3.257 11 2.756 75 3.768 32 3.229 66 3.748 28 3.171 62 3.718 24 3.093 315 Table 3* Group velocities interpreted from the two- dimensional plots (continued) NDI COMP 3, February 5, 1966 Period Velocity Pe 97 3.896 55 89 3.896 49 87 3.872 45 75 3.872 4l 70 3.849 38 66 3.826 32 62 3. 826 28 Velocity Period Velocity 3.803 24 3.260 3.748 22 3.235 3.631 18 3.211 3.401 13 3.172 3.392 13 3.172 3.335 11 3.243 3.284 10 3.233 316 Table 4. Group velocities interpreted from two— dimensional plots. ANP COMP 5, February 7 * 1966 Period Velocity Period Velocity Period Velocity 120 4.051 66 3.815 32 3.475 107 4.051 62 3.773 28 3.425 97 4.051 55 3.709 24 3.354 89 4.031 49 3.659 18 3. 220 81 3.991 45 3. 604 15 3.157 75 3.933 4l 3.551 13 3.133 70 3.870 38 3.515 11 3.137 LAH COMP 5, September 28 , 1966 Period Velocity Period Velocity Period Velocity 71 3.722 39 3.384 15 3.H5 66 3.701 33 3.357 13 3.069 62 3.679 28 3.331 12 3.025 55 3.596 25 3.305 46 3.468 22 3.279 42 3.411 18 3.254 SHX COMP 5, March 23* 1966 Period Velocity Period Velocity Period Velocity 120 3.926 62 3.703 24 3.185 107 3.882 55 3.637 22 3.133 97 3.834 49 3.562 18 3.089 89 3.796 45 3.501 15 3.024 81 3.772 4l 3.459 13 2.957 75 3.755 38 3.435 11 3.005 70 3.743 32 3.326 10 3.171 66 3.727 28 3.171 317 Table 4. Group velocities interpreted from two dimensional plots (continued) LAH COMP 5, March 23, 1966 Period Velocity Period Velocity Period Velocity 120 4.051 66 107 4.051 62 97 4.051 55 89 4.031 49 81 3.991 45 75 3.933 4l 70 3.870 38 3.315 32 3.473 3.773 28 3.425 3.709 24 3.334 3.659 18 3.220 3•604 15 3.157 3.551 13 3.133 3.515 11 3.137 318 Table 5* Group velocities interpreted from tbe two — dimensional plots. SEO COMP 4, February 5* 1966 Period Velocitv Period Velocity Period Velocity 76 3.282 46 3.359 22 2.727 71 3.308 42 3.308 18 2.965 66 3.359 39 3.233 15 2.965 6l 3.359 33 3.161 13 2. 898 55 3.386 28 2.944 11 2.898 50 3.386 25 2.774 10 2.704 HKC COMP 4, J anuary 20, 1967 Period Velocity Period Velocity Period Velocity 120 3.465 62 3.693 24 3.007 107 3.563 55 3.666 22 2.983 97 3. 6l4 49 3.6x4 18 2.893 89 3.640 45 3.563 15 2.915 81 3.640 4l 3.513 13 2.871 75 3 • 666 38 3.465 11 2.871 70 3 • 666 32 3.396 10 2.515 66 3.693 28 3.351 SEO COMP 4, February 7 > 1966 Period Velocity Period Velocity Period Velocity 89 3.580 50 3.397 22 2. 921 82 3.580 46 3.332 18 2.876 76 3.580 42 3.135 15 2.812 71 3.580 39 3.091 13 2.791 66 3.556 33 3.048 12 2.751 62 3.533 28 2.943 11 2.771 55 3.486 25 2.921 319 Table 5. Group velocities interpreted from the two- dimensional plots (continued) HKC COMP 6, January 18, 1967 Period Velocity Pe 81 4. l4l 45 75 4. l4l 41 70 4.115 38 66 4.115 32 62 4.115 28 55 4.089 24 49 4.037 Velocity Period Velocity 3.963 22 3.262 3.868 18 3.257 3.799 15 3.230 3.608 13 3.224 3.485 11 3.182 3.358 IO 3.182 320 Table 6. Group velocities interpreted from the two- dimensional plots. SEO COMP 4, February 13, 1966 (April 15, 1974) Period Velocity Period Velocity Period Velocity 120 3.647 61 3.647 25 3.094 107 3.626 55 3.647 22 2.945 97 3.647 50 3.626 18 2.873 89 3.668 45 3.606 15 2.847 82 3 • 668 4l 3.556 13 2.847 76 3.668 39 3.498 11 2.9 86 71 3 • 668 33 3.361 10 2.986 66 3.647 28 3.210 ANP COMP 4, November 13, 1965 Period Velocity Period Velocity Period Velocity 81 3.510 45 3.510 22 2.931 75 3.510 4l 3. 484 18 2.906 70 3.531 38 3.458 15 2.975 66 3.531 32 3.H0 13 3.024 62 3.531 28 3.069 11 3.H3 55 3.531 24 2.931 IO 3.089 49 3.531 BAG COMP 4, January 20, 1967 Period Velocity Period Velocity Period Velocity 81 3.571 45 3.638 22 2.953 75 3.679 4l 3.617 18 2.940 70 3.720 38 3.571 15 2.879 66 3.743 32 3.259 13 2. 813 62 3.743 28 3.216 11 2.980 55 3.700 24 3.159 10 2.985 49 3.658 321 Table 6. Group velocities interpreted from the two- dimensional plots (continued) HKC COMP January 18, 1967 Period Velocity Period 81 3.7^1 49 75 3.719 45 70 3.698 kl 66 3.698 38 62 3.698 32 55 3.719 28 Velocity Period Velocity 3.719 2h 3.192 3.698 22 3.192 3.677 18 3.085 3.635 15 3.037 3.516 13 2.817 3.213 11 2.858 IO 2.901 322 Table 7* Group velocities interpreted from the two- dimensional plots. CHG COMP 4, January 20, 1967 Period Velocity Period Velocity Period Velocity 97 3.592 55 3.413 24 3.152 89 3.592 49 3.371 22 3 . H 7 81 3.569 45 3.330 18 2.946 75 3.546 4l 3.251 15 2.957 70 3.523 38 3.214 13 3.021 66 3.500 32 3.l4l 11 3.111 62 3.^56 28 3.152 10 2. 840 CHG COMP 4, June 16, 1973 Period Velocity Period Velocity Period Velocity 81 3 . 5 H 45 3.488 22 3.133 75 3 . 5 H 4l 3.397 18 3.130 70 3 . 5 H 38 3.375 15 2 . 9 H 66 3 . 5 H 32 3 . 3 H 13 2.994 62 3 . 5 H 28 3.290 11 2.994 55 3 . 5 H 24 3.250 10 3.082 49 3 . 5 H CHG COMP 4, January l6, 196 7 Period Velocity Period Velocity Period Velocity 120 3.670 62 3.316 25 2.984 108 3.647 55 3.202 22 3.054 98 3.624 50 3.095 18 3.116 89 3.601 46 3.007 15 3.137 82 3.557 42 2.939 13 3.158 76 3.513 39 2.895 12 3.137 71 3.471 33 2.916 11 3.095 66 3.^09 28 2.939 323 Table 7. Group velocities interpreted from the two dimensional plots (continued) LAH COMP 4, March 7, 1966 Period Velocity Period Velocity Period Velocity 120 3.507 62 3. ho5 25 3.072 108 3.553 55 3.309 22 3.072 98 3.533 50 3.196 18 3.092 89 3.528 46 3.133 15 3.047 82 3.507 42 3.112 13 2.862 76 3.507 39 3.092 12 2.820 71 3.507 33 3.02*7 11 2.820 66 3.481 28 3.02*7 Appendix VI. Computer Program Lists of Multiple Filtering 325 nnr> r > oor>nnr» DIWE N3ION X(1101 ) *Y (1100 ) *TL(1100),FRE(11GC)* A M I N (110 0) * 1 PH IN <1 ICO) *CPHI(1 ICO), F INS(1100) ,CX<1100) ,UU(1 ICO) •ANP(25,150), 2 AMP(1 ICO) .PHI (1100) • U<1100)*T(1100)*TML(1 ICO) ,TT(1100 >,ACN(50 0) 3*AIP<1100) ,PHA(110C) ,QCX(12Q0>,AMU(100),NAME(20)•F(11C0) CCNPLEX CX*CPHI»CP*QCX THE PARAMETERS TO DE READ IN ARE: LX THE TOTAL INPUT POINTS HAS TO BE 2**N JJ THE beginning o c filtering frequency JN THE END OF I THAT IN THE FILTERING RANGE PEAD(5,66) NAME WRITE(6»86) NAME 8 5 FORMAT( 2 0 & 4 ) READ(5 ,87 ) LX,JJ,JN,APHA,DX WPITE(£,8 7)LX,JJ»JN,APHA,DX 87 FORMAT(3I5,2F5*0) ' L V = LX/2 READ(5,12) DI ST,TCCN 12 FORMAT(2C1C*3) RE AD(5,20) ( X( I) ,Y(I ) ,1=1 ,LX) 20 FORMAT(A(2F10.3)) CALCULATE HE GROUP VELOCITY DIVIDE THE DIST BY ARRIVING TIME MM = 0 DO 7 1=1,LX U< I )=DI ST/<TCCN+X( I ) ) I f ( MM *GT. 2) GO TO 6 6 IF(U( I ).LT.2.o •AND* U(I)«GT»2*1) N N=I CX(I)=CMPLX(Y(I),C»0) 7 CONTINUE 3 3 FO R M AT ( i C X , F 1 0 . 3 ) LL=1 WRITE(5,33 ) U<LL),U (NN),LL,NN 75 FORMAT<2-1C.3,215) 3 1 FORMAT(12-10.5 ) to ON FAST F0UFI5R TRANSFORM SIGNI=1.G CALL FCRK(LX.CX,SIGNI ) F A = 0 • 0 DC 3 1=1,LV F(1)=I/(LX*DX) AVO(I )=CAFS(CX(I ) ) PHA(I)=ATAN2(AIMAG(CX(I)),REAL(CX{I)))/6.2£32 IF ( I .LG. 1 ) GO TO 24 DIF = A3S(PHM T )-DrlA( I — 1 ) ) I F ( (PHA( I) .LT. C.O) .AND. {DIF.GT. C.5 )) PA=3A+1.C PHA( I )=CHA(I > + ^A 24 T ( I ) =1 . / F( I) 3 CCNTlNLr. WR ITC(6*13) ( T( I ) .F( I ) ,AMP( I) ,PHA{ I ) *1=1 *LM) 13 FCfi’ -iAT (4Fo0. 5 ) CALL PLOT(F,AMP,LM*l*LM) CALL PLOT(F*PHA*LM*l ,LM) DLT=ALCG(1.1) PI=3.1416 SC=SQRT(1./LX) CF=SC**2/DX FC=1./15 F G = I . / 1 C C CP=CMPLX(O.C .1.5703) M=1 INSTRUMENTAL CORRECTIONS DO 1C I = ).,LX FRE(I)= I*CF T( I ) = 1 ./FRE( I ) I F( T(I).LT.16 0. .AND. T(I)•GT.120• ) JJ=I IF( T(I).LT. 20. .AND. T( I )•GT. 10.) JN=I TL(I )=ALCG(T { I ) ) AVD<I )=CARS(CX(I ) ) PHI ( I )=ATAN2(A IMAG(CX( I)) ,REAL(CX(I ) ) ) AM IN(I ) = FPE(I)**3/(2*PI*{FO**2 + FPE( I ) * *2)*(FG**2 + FRE(I ) **2) ) PH IN ( I ) = ( A T A N 2 ( F Cl * F R E ( I ) ) +ATAN2 ( FG* FRE( I ) ) ) / PI-0.25 I F (A MIN ( I ) •LT.0•0 C 0 5 ) AMP( I ) = 0 o 0 IF(A M I M I ).LT.C.0 0 05)GO TO 56 AMP ( I )=A^< I )/AM IN< I ) 56 Phl(1)=PHI<I)-oHIN(I)*PI CPHI (I )=CMFLX(0.O, PHI(I)) CCX( I ) =AMP(I )*C£XP(C°HI (I ) ) 10 CONTINUE WPITE*t*35) T<JJ),T(JN),JJ,JN FREQUENCY FILTERING * DETERMINE FREQUENCY INCREMENT 11=1 DO 15 J=JJ,JN,II PA ND = F RE(J)*4« APHA=!200#*BAND IF(j.LE.32> 11=2 IF(J♦GT• 22 «AND# J.LE» 52) 11=4 IFU.GT. 52)11=10 IF(J * GT• 9 0 11=20 IF( J • S T • 200) 11 = 4C IF( J * G T• 4 C 0) II=SC FILTERING BY APHA(FI-FJ/FI)**2 55 DC 10 1=1,LX FIN.A ( I > = 2x c(-*ohA*((FRE ( I)-FR2(J))/FRE(J))**2) CX< I ) = 0CX{ I )*^ INS( I ) IF(ABS(FRE(I)--RE(J) )« GT•BAND) CX(I ) = C * G 16 CONTINUE 2 9 F 2 R M A T ( 1 2 F 1 C • 5 ) INVERSE FOURIER TRANSFORM SIGN I=-1 .0 CALL FCRK(LX,CX,SIGNI ) A C. C N = 0 • 1 NORMALIZATION THE MAXMUM AMPLITUDE TO 100 IN EACH FREQU :c n 1 = 3 * l x /■ I r ( • ) = c A S ( C X (I ) ) IF (A Ip(I ) .CT• ACCN ) GO TO 9 G 2 T C 8 9 ACCN = AIP( I 3 A M L ( M ) =r U ( I 3 a PHA< I )=ATA.N2( AIMAG(CX< I ) KREAL(CX( I ) > ) 11 CONTINUE A C M M )=ACC N DO 14 1 = 1 »LX lfi A IP( I )=AIP{I )*100/ACCN 27 FORMAT* 9F12.4) 329 TML(M)=TL(J) AIF(LM)=O.C N = 1 l'U(l)=U(LL) ANP( 1 ) =AIP(LL) L 1 = LL +1 DC 17 I=L1*NN IF(AP;S(UU(N)-U(I )).LT.Q*02> GO TO 17 N = N + 1 UUCN)=U<I> ANP(M,N)=AIP(I> 17 CONTINUE IT (M ) =EXr> ( TML ( M) ) WRITE CUT AND PUNCH OUT THE CARD OUTPUT WRITE(6*19) ( TML(M)»UU(I)»AN?(M.I),TT(M),ACN(«),1-1*N) 19 FORMAT(5F10*3) w = v +1 15 C O M I NILE K = V— 1 WRITC(e,C14 ( AMU( I) »TML(I ) *ACN( n , T T ( I ) . 1 = 1 .M) NR I TEC 7*21 ) ( AMUC I ) *TML( I ) . ACN( I ) *TT( I ) . 1 = 1 *M ) 2 1 FC&MAT(4 FIC*31 CALL GRAPH(M,UU.ANP«TT*N) q g STOP END SUBROUTINE G R A °H(M♦U U * A NP * T T * N ) CINENSICN U U ( 1 5 3 )*ANP(2 5*150)»TT(150) WRITE(6 * 14 ) ( TT(M-I+1 ) * I = 1 * M ) 14 FORMAT(/,8X,3CF4*0) CO 12 J M . N Wc ITE(6 »15 ) UU(J). (ANP(M-I+l♦J ),1=1,M) 12 CONTINUE 15 PCPMATC 2 X » F6•3 » 3GF 4*0) RETURN ENC SUDk 1UTIN-: F0 9K(LXfCX*SIGNl) FAST -TU • • I r - ' F LX C.X(K) = SUM ( OX ( J ) *EXP( 2*P I *SIGN I *!*< J-l ) *< K- 1 ) /LX ) ) ! J-l FOR K -1 ...... LX s THE Ffi'OUcNCY INCRE IS -EQUAL TO 1./{LX*DX) »DX IS THE TIME INCRE. ! CCVPLIX CX(LX).CARG,CEXP,CW*CTEMP j SC=3QWT(1./LX) I J=1 ! 00 5 I-1,LX IF( I • G T • J> GO TQ 2 CTEMP-CX{J )*SC c x(j > =cx(i ) *sc C X ( I ) = C T 2 M F ! 2 V-LX/2 3 IF ( J • L E • M ) GQ TO 5 | J-J-vl M = V / 2 IF(M.GF.l) GO TO 3 -5 J - J -f M L = 1 6 IST=o=2*L 00 3 NI = 1,L CARS=(C..l.)*<3.14159265*SIGNI*(M-1>>/L CW=CEXP(CARG) CO 3 I-M.LX,I STEP CTIMF=CW*CX<I+L) CX(I+ L ) =CX(I)-CTEMP a CX(I )=CX(I)+CTEMP L= I STEP j IF(L•LT•LX) GO TQ 6 1 9 RETURN ENQ CO U o SUPROUTINE PLOT(X,Y«NL*NF*NR) LOGICAL AXIS DIMENSION X(1) ,Y(NR,1),YLINE(100) *CHAR(10) CCMMCN/SCALE/YMIN,SFACT CATA CHAR<1)/lH*/.CHAR(2)/lHA/,CHAR(3)/lH3/,3LK/lH /* GRDCHR/1H• C GET SCALING FACTOR C GET MAX AND MIN VALUES YMAX = Y(i , 1 ) YVIN=Y(1 * 1 ) DC 1C J=1,NF DO 1C 1 = 1 * NL I F (Y ( I , J ) .GT.YMAX) YMAX = Y(I ,J) IF(Y( I , J ) #LT#YMIN) YMIN = Y(I*J) 10 CONTINUE C CALCULATE SCALE FACTOR SFACT=RO#/(YMAX-YMIN) AX I S=#FALSE# IF(3IGMYMAX.YMIN)#EQ#YMAX) GO TO 15 AX IS=#TRUE • 15 CCNTINUE IAXIS=ISCALE(C#) C PLOT THE FUNCTION DC. ?.C 1 = 1 « NL DO 2 C 11=1,100 20 YL INE( I I ) =CLK IF(A X I S)yl INE( IAX IS)=GRDCHR DO 25 J=2,NF IY=I SCALE(Y( I ,J) ) YL INE( IY) = CHAR(J ) 25 CCNTINUE toP IT E ( 6 , 1 C C ) X ( I ) , YL I NE IOC FORMAT(1H ,G12.5,?X,60A1,40A1) 3 0 CCNTINUE PL T'JON END FUNCTION ISCALE(Y) CC VMCN/SCALc/YMIN,S = ACT ISCAL" = < Y-YMIN >*SFACT + 1.5 RETURN END

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Asset Metadata

Creator Tung, James Ping-Ya (author)

Core Title The surface wave study of crustal and upper mantle structures of mainland China

Degree Doctor of Philosophy

Degree Program Geological Sciences

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag geophysics,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c29-341327

Unique identifier UC11220318

Identifier DP28534.pdf (filename),usctheses-c29-341327 (legacy record id)

Legacy Identifier DP28534.pdf

Dmrecord 341327

Document Type Dissertation

Rights Tung, James Ping-Ya

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA