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40’ 30’ 20’ 10’ 122oW
30’
40’
50’
38oN
10’
elevation(m)
−100
0
100
200
300
400
500
600
700
San
Pablo
Bay
San
Francisco
Bay
Pacific
Ocean
Carquinez
Strait
Rodeo
San
Rafael
Oakland
Alameda
Vallejo
Mare
Island
San
Francisco
Fort Point
Presidio
Salsalito
Palo
Alto
Alvisto
Richmond
Berkeley
Hunters
Pt.
San
Mateo
Hayward
5 10 15 20
(km)
waves at
Golden Gate
50%
50%
10%
10%
Figure 2.7: Topographic map of San Francisco Bay area with Magoon’s (1966) waveheight
attenuation estimates for a wave at Golden Gate, based on observations from the 1960 (Chile)
and 1964 (Alaska) tsunamis.
and even if a large slide were to enter the Bay, the volume of water displaced would be
small, presumably limiting the size of the resulting wave.
The Golden Gate is a steep gorge that separates San Francisco from Marin County.
The Bay reaches its maximum depth of 109m at the Golden Gate. Only the headlines
on the north side are steep enough to pose any slide hazard into the Bay and historically
slides in this area have been small and few (Wentworth et al., 1997). There is no credible
basis to support a large slide in this area.
The Carquinez Strait connects San Pablo Bay to Suisan Bay (Figure 2.7). Only the
western end is steep enough to pose slide hazards. The Strait is less than a kilometer
58
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 73 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 40’ 30’ 20’ 10’ 122oW 30’ 40’ 50’ 38oN 10’ elevation(m) −100 0 100 200 300 400 500 600 700 San Pablo Bay San Francisco Bay Pacific Ocean Carquinez Strait Rodeo San Rafael Oakland Alameda Vallejo Mare Island San Francisco Fort Point Presidio Salsalito Palo Alto Alvisto Richmond Berkeley Hunters Pt. San Mateo Hayward 5 10 15 20 (km) waves at Golden Gate 50% 50% 10% 10% Figure 2.7: Topographic map of San Francisco Bay area with Magoon’s (1966) waveheight attenuation estimates for a wave at Golden Gate, based on observations from the 1960 (Chile) and 1964 (Alaska) tsunamis. and even if a large slide were to enter the Bay, the volume of water displaced would be small, presumably limiting the size of the resulting wave. The Golden Gate is a steep gorge that separates San Francisco from Marin County. The Bay reaches its maximum depth of 109m at the Golden Gate. Only the headlines on the north side are steep enough to pose any slide hazard into the Bay and historically slides in this area have been small and few (Wentworth et al., 1997). There is no credible basis to support a large slide in this area. The Carquinez Strait connects San Pablo Bay to Suisan Bay (Figure 2.7). Only the western end is steep enough to pose slide hazards. The Strait is less than a kilometer 58 |
