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Japan
1994
2006
2007 Crescent City
California
140 160 180 200 220 240
0
10
20
30
40
50
60
Figure 2.5: Epicenter of 1994, 2006 and 2007 events.
2.2.2 Nearfield Tsunami Sources for California
Here a “variety” of tectonic sources was used depending on the study region. Four
Cascadia cases are considered for northern California (N.C.); in addition to the three
long farfield ruptures a scenario rupturing the Little Salmon Fault is also considered
(Bernard et al., 1994). Two local ruptures, on the Hayward-Rodgers Creek and San
Gregorio faults, are studied in the San Francisco Bay region (S.F. Bay) (Borrero et al.,
2006a). Seven different fault ruptures are used in the detailed modeling of southern
California (S.C.), which are discussed in Borrero et al. (2001) and Borrero et al. (2004b).
Local earthquakes in southern California are generated at the Channel Islands, Anacapa-
Dume, Santa Monica Bay, Lausen Knoll, San Clemente and San Mateo (Table 2.3).
In the study of local sources, aside dislocations, landslide–generated tsunamis are
also considered for San Francisco Bay and southern California. A dipole source with a
10mwaveheight is used in the Farallon Islands to simulate a landslide–triggered tsunami
52
Object Description
| Title | Deterministic and probabilistic tsunami studies in California from near and farfield sources |
| Author | Uslu, Burak |
| Author email | uslu@usc.edu; burak.uslu@noaa.gov |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Civil Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2007-09-21 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-30 |
| Advisor (committee chair) | Synolakis, Costas E. |
| Advisor (committee member) |
Bardet, Jean-Pierre Okal, Emile A. Moore, James Elliott, II |
| Abstract | California is vulnerable to tsunamis from both local and distant sources. While there is an overall awareness of the threat, tsunamis are infrequent events and few communities have a good understanding of vulnerability. To quantitatively evaluate the tsunami hazard in the State, deterministic and probabilistic methods are used to compute inundation and runup heights in selected population centers along the coast.; For the numerical modeling of tsunamis, a two dimensional finite difference propagation and runup model is used. All known near and farfield sources of relevance to California are considered. For the farfield hazard analysis, the Pacific Rim is subdivided into small segments where unit ruptures are assumed, then the transpacific propagations are calculated. The historical records from the 1952 Kamchatka, 1960 Great Chile, 1964 Great Alaska, and 1994 and 2006 Kuril Islands earthquakes are compared to modeled results. A sensitivity analysis is performed on each subduction zone segment to determine the relative effect of the source location on wave heights off the California Coast.; Here, both time-dependent and time-independent methods are used to assess the tsunami risk. In the latter, slip rates are obtained from GPS measurements of the tectonic motions and then used as a basis to estimate the return period of possible earthquakes. The return periods of tsunamis resulting from these events are combined with computed waveheight estimates to provide a total probability of exceedance of given waveheights for ports and harbors in California. The time independent method follows the practice of past studies that have used Gutenberg and Richter type relationships to assign probabilities to specific tsunami sources.; The Cascadia Subduction Zone is the biggest nearfield earthquake source and is capable of producing mega-thrust earthquake ruptures between the Gorda and North American plates and may cause extensive damage north of Cape Mendocino, to Seattle. The present analysis suggests that San Francisco Bay and Central California are most sensitive to tsunamis originating from the Alaska and Aleutians Subduction Zone (AASZ). An earthquake with a magnitude comparable to the 1964 Great Alaska Earthquake on central AASZ could result in twice the wave height as experienced in San Francisco Bay in 1964.; The probabilistic approach shows that Central California and San Francisco Bay have more frequent tsunamis from the AASZ, while Southern California can be impacted from tsunamis generated on Chile and Central American Subduction Zone as well as the AASZ. |
| Keyword | assessment; California; hazard; model; probability; tsunami |
| Geographic subject | capes: Kamchatka; islands: Kuril Islands; fault zones: Cascadia Subduction Zone |
| Geographic subject (state) | California; Alaska |
| Geographic subject (country) | Chile |
| Coverage date | 1952/2008 |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1706 |
| Contributing entity | University of Southern California |
| Rights | Uslu, Burak |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-uslu-2434 |
| Archival file | uscthesesreloadpub_Volume40/etd-uslu-2434.pdf |
Description
| Title | Page 67 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | Japan 1994 2006 2007 Crescent City California 140 160 180 200 220 240 0 10 20 30 40 50 60 Figure 2.5: Epicenter of 1994, 2006 and 2007 events. 2.2.2 Nearfield Tsunami Sources for California Here a “variety” of tectonic sources was used depending on the study region. Four Cascadia cases are considered for northern California (N.C.); in addition to the three long farfield ruptures a scenario rupturing the Little Salmon Fault is also considered (Bernard et al., 1994). Two local ruptures, on the Hayward-Rodgers Creek and San Gregorio faults, are studied in the San Francisco Bay region (S.F. Bay) (Borrero et al., 2006a). Seven different fault ruptures are used in the detailed modeling of southern California (S.C.), which are discussed in Borrero et al. (2001) and Borrero et al. (2004b). Local earthquakes in southern California are generated at the Channel Islands, Anacapa- Dume, Santa Monica Bay, Lausen Knoll, San Clemente and San Mateo (Table 2.3). In the study of local sources, aside dislocations, landslide–generated tsunamis are also considered for San Francisco Bay and southern California. A dipole source with a 10mwaveheight is used in the Farallon Islands to simulate a landslide–triggered tsunami 52 |
