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Location Longitude Latitude Depth (m)
Crescent City 234.95 42.02 422
Pt. Reyes 236.55 38.35 344
San Francisco 237.33 37.72 31
Monterey 237.02 37.72 57
San Luis Obispo 238.95 35.14 448
Los Angeles 241.88 33.61 52
San Diego 242.68 32.713 83
Table 3.5: Coordinates and water depth of the offshore locations used in this study for calculat-ing
probabilities of occurance.
Waveheight (cm)
50 100 150 250 300 400
Crescent City 26 52 105 250 293 469
Return Period (Yr)
Pt. Reyes 42 126 195 313 426 —
San Francisco 16 60 139 261 426 —
Monterey 71 174 276 — — —
San Luis Obispo 68 162 249 — — —
Los Angeles 53 293 — — — —
San Diego 67 218 335 — — —
Table 3.6: Return Period of tsunami waveheights at the California offshore locations listed using
earthquake generated waves from the Kuril Islands, the West Aleutians, the Alaska-Aleutians,
the Central America and the South America–Chile subduction zones, by assigning return periods
from the slip rates from Table 3.3
Diego) are more at risk from the CASZ and SASZ. In turn, directivity effects target Cal-ifornia
more efficiently from AASZ than from in Central or South America Subduction
Zones. The combined effect is a lower tsunami risk in southern California. Specific
comparisons, for example between San Francisco and Crescent City, or between Los
Angeles and San Diego would require simulations of individual responses of the bays
and harbors on a much finer scale than performed here.
132
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 147 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | Location Longitude Latitude Depth (m) Crescent City 234.95 42.02 422 Pt. Reyes 236.55 38.35 344 San Francisco 237.33 37.72 31 Monterey 237.02 37.72 57 San Luis Obispo 238.95 35.14 448 Los Angeles 241.88 33.61 52 San Diego 242.68 32.713 83 Table 3.5: Coordinates and water depth of the offshore locations used in this study for calculat-ing probabilities of occurance. Waveheight (cm) 50 100 150 250 300 400 Crescent City 26 52 105 250 293 469 Return Period (Yr) Pt. Reyes 42 126 195 313 426 — San Francisco 16 60 139 261 426 — Monterey 71 174 276 — — — San Luis Obispo 68 162 249 — — — Los Angeles 53 293 — — — — San Diego 67 218 335 — — — Table 3.6: Return Period of tsunami waveheights at the California offshore locations listed using earthquake generated waves from the Kuril Islands, the West Aleutians, the Alaska-Aleutians, the Central America and the South America–Chile subduction zones, by assigning return periods from the slip rates from Table 3.3 Diego) are more at risk from the CASZ and SASZ. In turn, directivity effects target Cal-ifornia more efficiently from AASZ than from in Central or South America Subduction Zones. The combined effect is a lower tsunami risk in southern California. Specific comparisons, for example between San Francisco and Crescent City, or between Los Angeles and San Diego would require simulations of individual responses of the bays and harbors on a much finer scale than performed here. 132 |
