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Japan are triggered along the Japan Subduction Zone (JSZ) located along the NE of
Honshu Island. The JSZ is possibly an extension of the KSZ. This JSZ has produced
very large earthquakes, notably the 1896 Mw = 8.0–8.5 Sanriku event. The latter not
only triggered a catastrophic tsunami locally, but in California also caused damage at
Santa Cruz, was observed at Mendocino and was reportedly recorded at Sausalito. The
1933 normal faulting event ( Mw # 8.3 − 8.7) also happened off the coast of Sanriku
was recorded in six locations California (Lander et al., 1993; Dengler et al., 2008).
The JSZ is modeled with two different Mw = 8.8 scenarios, one with 900km ×
100km rupture and 5m slip, and the other with 400km × 100km with 10m slip.
On 22 May 1960, the South American Subduction Zone (SASZ) triggered the
largest earthquake (Mw = 9.5) that has ever been instrumentally recorded Berkman and
Symons (1964) with runup in the immediate area reaching 25m (Plafker, 1972; Insti-tuto
Hidrografico de la Armada, 1982) and causing at least 1200 deaths. The tsunami
crossed the Pacific and caused damage throughout the Pacific basin, with 61 casualties
in Hawaii (Cox and Mink, 1963) and 180 in Japan (Duke, 1960). The wave caused over
$1 million in damage in Los Angeles and Long Beach harbors, as well as a 2.5m peak
to trough wave recorded in Crescent City tide gauge (Berkman and Symons, 1964).
In modeling the SASZ two scenarios were used in this analysis. First, the 1960
Great Chilean Earthquake was modeled with a 1000km × 100km rupture with 20m
slip to represent a MW 9.3 earthquake, as per Plafker (1972). The other scenario was
a Mw = 9.4 event in the northern part of the subduction zone, involving a rupture
extending into Peru along a 1400km × 100km fault area and a 25m slip.
49
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 64 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | Japan are triggered along the Japan Subduction Zone (JSZ) located along the NE of Honshu Island. The JSZ is possibly an extension of the KSZ. This JSZ has produced very large earthquakes, notably the 1896 Mw = 8.0–8.5 Sanriku event. The latter not only triggered a catastrophic tsunami locally, but in California also caused damage at Santa Cruz, was observed at Mendocino and was reportedly recorded at Sausalito. The 1933 normal faulting event ( Mw # 8.3 − 8.7) also happened off the coast of Sanriku was recorded in six locations California (Lander et al., 1993; Dengler et al., 2008). The JSZ is modeled with two different Mw = 8.8 scenarios, one with 900km × 100km rupture and 5m slip, and the other with 400km × 100km with 10m slip. On 22 May 1960, the South American Subduction Zone (SASZ) triggered the largest earthquake (Mw = 9.5) that has ever been instrumentally recorded Berkman and Symons (1964) with runup in the immediate area reaching 25m (Plafker, 1972; Insti-tuto Hidrografico de la Armada, 1982) and causing at least 1200 deaths. The tsunami crossed the Pacific and caused damage throughout the Pacific basin, with 61 casualties in Hawaii (Cox and Mink, 1963) and 180 in Japan (Duke, 1960). The wave caused over $1 million in damage in Los Angeles and Long Beach harbors, as well as a 2.5m peak to trough wave recorded in Crescent City tide gauge (Berkman and Symons, 1964). In modeling the SASZ two scenarios were used in this analysis. First, the 1960 Great Chilean Earthquake was modeled with a 1000km × 100km rupture with 20m slip to represent a MW 9.3 earthquake, as per Plafker (1972). The other scenario was a Mw = 9.4 event in the northern part of the subduction zone, involving a rupture extending into Peru along a 1400km × 100km fault area and a 25m slip. 49 |
