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Table 2.4: Source parameters used in modeling from Bernard et al. (1994) and Satake et al.
(2003) and 1964 Alaska event.
Sources L (km) W (km) Disp (m) Mw
CSZ SN Gorda Segment Narrow 240 80 8 8.44
CSZ SW Gorda Segment Wide 240 100 8 8.51
CSZ SP1 Gorda–Little Salmon 1 240 100 7 8.48
CSZ SP2 Gorda Segment Narrow 2 240 100 8 8.50
CSZ N Juan de Fuca Segments 800 100 11 8.95
CSZ L Full Rupture 1040 100 11 9.02
C. Mendo. 1992 21.5 16 2.7 6.96
located in northern California near the south end of the CSZ and is capable of producing
infrequent earthquakes with Mw > 7.6, per Clarke and Carver 1992). Scenario CSZ
N considers only slip on the northern or Juan de Fuca segment of the CSZ, with 11m
of slip along a 800km × 100km rupture, stopping just north of the California border.
Scenario CSZ L, the largest magnitude event modeled, simulates rupture of the entire
subduction zone with characteristics believed similar to the 1700 rupture (Atwater and
Hemphill-Haley, 1997). CSZ-L combines the average slip and the dimensions of Satake
et al. (2003) with partitioned slip on the Gorda segment similar to SP1. The northern
800km is characterized by a slip distribution with an average of 12m. The southern part
includes slip on both the CSZ and the Little Salmon fault and is identical to SP2. The
initial conditions for these scenarios are shown in Figure 1.8.
The 1992 Cape Mendocino earthquake was also used as an example source for a
local event in northern California with a Mw # 7.0.
Tsunami Sources inside San Francisco Bay
For farfield scenarios, the “standard” sources of FACTS from subduction zones in the
Pacific were used, as discussed in see Chapter 1. In addition, sources within the Bay
54
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 69 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | Table 2.4: Source parameters used in modeling from Bernard et al. (1994) and Satake et al. (2003) and 1964 Alaska event. Sources L (km) W (km) Disp (m) Mw CSZ SN Gorda Segment Narrow 240 80 8 8.44 CSZ SW Gorda Segment Wide 240 100 8 8.51 CSZ SP1 Gorda–Little Salmon 1 240 100 7 8.48 CSZ SP2 Gorda Segment Narrow 2 240 100 8 8.50 CSZ N Juan de Fuca Segments 800 100 11 8.95 CSZ L Full Rupture 1040 100 11 9.02 C. Mendo. 1992 21.5 16 2.7 6.96 located in northern California near the south end of the CSZ and is capable of producing infrequent earthquakes with Mw > 7.6, per Clarke and Carver 1992). Scenario CSZ N considers only slip on the northern or Juan de Fuca segment of the CSZ, with 11m of slip along a 800km × 100km rupture, stopping just north of the California border. Scenario CSZ L, the largest magnitude event modeled, simulates rupture of the entire subduction zone with characteristics believed similar to the 1700 rupture (Atwater and Hemphill-Haley, 1997). CSZ-L combines the average slip and the dimensions of Satake et al. (2003) with partitioned slip on the Gorda segment similar to SP1. The northern 800km is characterized by a slip distribution with an average of 12m. The southern part includes slip on both the CSZ and the Little Salmon fault and is identical to SP2. The initial conditions for these scenarios are shown in Figure 1.8. The 1992 Cape Mendocino earthquake was also used as an example source for a local event in northern California with a Mw # 7.0. Tsunami Sources inside San Francisco Bay For farfield scenarios, the “standard” sources of FACTS from subduction zones in the Pacific were used, as discussed in see Chapter 1. In addition, sources within the Bay 54 |
