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L W slip Dip Rake dep. seg’s Mw region
Local Tectonics (km) (km) (m) (deg) (deg) (km)
Cascadia SN 240 80 8 10 90 5 2 8.44 N.C.
Cascadia SW 240 100 8 10 90 5 2 8.51 N.C.
Cascadia SP1 240 100 7 10 90 5 4 8.48 N.C.
Cascadia SP2 240 100 8 10 90 5 4 8.5 N.C.
CSZ N 800 100 11 n/a 90 n/a 16 8.95 N.C.
CSZ L 1040 100 11 n/a 90 n/a 22 9.02 N.C.
C. Mendo. 1992 21.5 16 2.7 12 107 6.3 1 6.96 N.C.
Hayward-Rodgers 10 18 1.5 70 -90 5 1 6.6 S.F. Bay
San Gregorio 50 15 2 60 90 5 1 7.1 S.F. Bay
Channel Islands 56 34 3.6 20 90 17 1 7.54 S. C.
Anacapa-Dume 40 18 2.5 55 90 15 1 7.15 S. C.
Santa Monica Bay 40 18 2.4 55 90 15 1 7.14 S. C.
Catalina Fault 164.3 14 4.46 n/a n/a n/a 7 7.66 S. C.
Lausen Knoll 16.7 12.5 2.2 n/a n/a 0.5 2 6.76 S. C.
San Clemente Is. 30 8 8 70 162 7.6 1 7.3 S. C.
San Mateo 31.9 12 4 45 120 0.5 3 7.11 S. C.
Local Slump/Slide positive wave negative wave
Farallon Islands 3 -7 S.F. Bay
Goleta 6 -18 S. C.
Palos Verdes 3 -7 S. C.
Table 2.3: Source parameters for nearfield tsunami scenarios.
and a similar source is also used around Palos Verdes. A bigger landslide source has
been used to model tsunamis around Goleta in Santa Barbara County by Borrero et al.
(2001).
Tsunamis from the Cascadia Subduction Zone
Six scenarios were modeled to assess the local tsunami hazard from a CSZ rupture. The
scenarios ranged in Mw from 8.4 to 9.0 and varied in slip, width and length of rupture
(Table 2.4). Scenarios SN and SW involve rupture of the southern or Gorda segment of
the subduction zone only, and differ only in the width of the rupture zone. Scenarios
SP1 and SP2 not only rupture the Gorda segment, but also partition the “available” slip
between the Little Salmon fault and the CSZ (the Little Salmon is shown in Figure 1.7
53
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 68 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | L W slip Dip Rake dep. seg’s Mw region Local Tectonics (km) (km) (m) (deg) (deg) (km) Cascadia SN 240 80 8 10 90 5 2 8.44 N.C. Cascadia SW 240 100 8 10 90 5 2 8.51 N.C. Cascadia SP1 240 100 7 10 90 5 4 8.48 N.C. Cascadia SP2 240 100 8 10 90 5 4 8.5 N.C. CSZ N 800 100 11 n/a 90 n/a 16 8.95 N.C. CSZ L 1040 100 11 n/a 90 n/a 22 9.02 N.C. C. Mendo. 1992 21.5 16 2.7 12 107 6.3 1 6.96 N.C. Hayward-Rodgers 10 18 1.5 70 -90 5 1 6.6 S.F. Bay San Gregorio 50 15 2 60 90 5 1 7.1 S.F. Bay Channel Islands 56 34 3.6 20 90 17 1 7.54 S. C. Anacapa-Dume 40 18 2.5 55 90 15 1 7.15 S. C. Santa Monica Bay 40 18 2.4 55 90 15 1 7.14 S. C. Catalina Fault 164.3 14 4.46 n/a n/a n/a 7 7.66 S. C. Lausen Knoll 16.7 12.5 2.2 n/a n/a 0.5 2 6.76 S. C. San Clemente Is. 30 8 8 70 162 7.6 1 7.3 S. C. San Mateo 31.9 12 4 45 120 0.5 3 7.11 S. C. Local Slump/Slide positive wave negative wave Farallon Islands 3 -7 S.F. Bay Goleta 6 -18 S. C. Palos Verdes 3 -7 S. C. Table 2.3: Source parameters for nearfield tsunami scenarios. and a similar source is also used around Palos Verdes. A bigger landslide source has been used to model tsunamis around Goleta in Santa Barbara County by Borrero et al. (2001). Tsunamis from the Cascadia Subduction Zone Six scenarios were modeled to assess the local tsunami hazard from a CSZ rupture. The scenarios ranged in Mw from 8.4 to 9.0 and varied in slip, width and length of rupture (Table 2.4). Scenarios SN and SW involve rupture of the southern or Gorda segment of the subduction zone only, and differ only in the width of the rupture zone. Scenarios SP1 and SP2 not only rupture the Gorda segment, but also partition the “available” slip between the Little Salmon fault and the CSZ (the Little Salmon is shown in Figure 1.7 53 |
