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earthquakes (Heaton and Kanamori, 1984; Atwater, 1987; Goldfinger et al., 2003). See
the northern California section of this chapter.
Using Satake et al. (2003), three earthquakes were used in this analysis from the CSZ
unit sources for farfield withMw ranging from 8.8 to 9.1 as possible farfield scenarios for
southern California, and an additional five for northern California. The first scenario is
800kmlong and 100kmwide with 11.1mslip corresponding to aMw = 8.9 earthquake.
The second is 600kmlong and 100kmwide with 10mslip, corresponding to aMw = 8.8
event. The third case is the full rupture of 1000km long and 100km wide with 20m slip
corresponding to a Mw = 9.1 event, as shown in Figure 2.2.
The 1964 Great Alaskan Mw = 9.2 Earthquake triggered the largest tsunami to hit
the California coastline in the past century. It resulted in observable crustal deformation
of unprecedented extend (Plafker, 1965), and the resulting observations were instru-mental
in proving the theory now known as plate tectonics. Hence, the Alaska–Aleutian
Subduction Zone (AASZ) is studied in detail, for tsunamigenesis, and another three
additional scenarios are considered, as discussed below.
The Mw = 9.2 earthquake struck the Prince William Sound area of Alaska on
March 28, 1964, at UTC=03:36:14. Its epicenter was located at 61.04! N. and 147.73!
W (Plafker, 1965; Johnson et al., 1996), about 120km SE of Anchorage and 90km E
of Valdez, with a hypocentral depth of about 25km. Before the 26 December 2004
Great Sumatran earthquake, it was believed to be the second largest earthquake ever
recorded, in instrumental history (Stein and Okal, 2005). Recently, the size of the 1964
earthquake has been recalculated and some have argued that it may have been reached
1.2 × 1023Nm, making it slightly larger than the 2004 Boxing Day earthquake (Nettles
et al., 2005; Synolakis and Kong, 2006).
45
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 60 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | earthquakes (Heaton and Kanamori, 1984; Atwater, 1987; Goldfinger et al., 2003). See the northern California section of this chapter. Using Satake et al. (2003), three earthquakes were used in this analysis from the CSZ unit sources for farfield withMw ranging from 8.8 to 9.1 as possible farfield scenarios for southern California, and an additional five for northern California. The first scenario is 800kmlong and 100kmwide with 11.1mslip corresponding to aMw = 8.9 earthquake. The second is 600kmlong and 100kmwide with 10mslip, corresponding to aMw = 8.8 event. The third case is the full rupture of 1000km long and 100km wide with 20m slip corresponding to a Mw = 9.1 event, as shown in Figure 2.2. The 1964 Great Alaskan Mw = 9.2 Earthquake triggered the largest tsunami to hit the California coastline in the past century. It resulted in observable crustal deformation of unprecedented extend (Plafker, 1965), and the resulting observations were instru-mental in proving the theory now known as plate tectonics. Hence, the Alaska–Aleutian Subduction Zone (AASZ) is studied in detail, for tsunamigenesis, and another three additional scenarios are considered, as discussed below. The Mw = 9.2 earthquake struck the Prince William Sound area of Alaska on March 28, 1964, at UTC=03:36:14. Its epicenter was located at 61.04! N. and 147.73! W (Plafker, 1965; Johnson et al., 1996), about 120km SE of Anchorage and 90km E of Valdez, with a hypocentral depth of about 25km. Before the 26 December 2004 Great Sumatran earthquake, it was believed to be the second largest earthquake ever recorded, in instrumental history (Stein and Okal, 2005). Recently, the size of the 1964 earthquake has been recalculated and some have argued that it may have been reached 1.2 × 1023Nm, making it slightly larger than the 2004 Boxing Day earthquake (Nettles et al., 2005; Synolakis and Kong, 2006). 45 |
