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Region Farfield Local
wave wave wave wave
height (+) height (-) height (+) height (-)
Richmond, outer (3) 0.96 -1.40 0.26 -0.18
Richmond, inner (1,5,6,11,12) 1.74 -1.56 0.49 -0.57
Carquinez, West (13,10) 0.37 -0.31 0.13 -0.21
Carquinez, East (13,10) 0.29 -0.17 0.10 -0.14
Golden Gate (19) 2.59 -3.61 0.60 -0.71
Presidio (20) 1.62 -2.93 0.40 -0.32
Region Farfield Local
current speed (m/s) current speed (m/s)
Richmond, outer (3) 0.92 0.21
Richmond, inner (1,5,6,11,12) 5.02 2.24
Carquinez, West (13,10) 0.45 0.20
Carquinez, East (13,10) 0.30 0.16
Golden Gate (19) 2.01 0.53
Presidio (20) 2.92 0.48
Table 2.7: The upper table shows the maximum wave height and drawdown at different locales
inside SF Bay, for farfield and local earthquake scenarios. The lower table shows the tsunami
induced current speeds at the same regions. The numbers in parentheses identify the marine oil
terminals in each location listed in Table 2.5.
response suggests that the CSZ probably is not the “dominant player” for tsunami haz-ards
along the central California and southern California coast. While great earthquakes
on the CSZ will produce significant and damaging runup in the immediate source area,
the modeling shows that most of this energy is radiated offshore towards Hawaii and
Japan, while relatively little wave energy is propagated south along the coast. This is
also shown in the maximum transpacific wave height plots for the Cascadia subduction
zone cases presented in Section 2.5. The smaller ruptures of the CSZ pose very little
hazard for San Francisco Bay. The largest South American sources pose less hazard
than Cascadia III (which produced the highest response among Cascadia events). A
much smaller response appears to be excited by sources in the Kuril Islands and Japan.
75
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 90 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | Region Farfield Local wave wave wave wave height (+) height (-) height (+) height (-) Richmond, outer (3) 0.96 -1.40 0.26 -0.18 Richmond, inner (1,5,6,11,12) 1.74 -1.56 0.49 -0.57 Carquinez, West (13,10) 0.37 -0.31 0.13 -0.21 Carquinez, East (13,10) 0.29 -0.17 0.10 -0.14 Golden Gate (19) 2.59 -3.61 0.60 -0.71 Presidio (20) 1.62 -2.93 0.40 -0.32 Region Farfield Local current speed (m/s) current speed (m/s) Richmond, outer (3) 0.92 0.21 Richmond, inner (1,5,6,11,12) 5.02 2.24 Carquinez, West (13,10) 0.45 0.20 Carquinez, East (13,10) 0.30 0.16 Golden Gate (19) 2.01 0.53 Presidio (20) 2.92 0.48 Table 2.7: The upper table shows the maximum wave height and drawdown at different locales inside SF Bay, for farfield and local earthquake scenarios. The lower table shows the tsunami induced current speeds at the same regions. The numbers in parentheses identify the marine oil terminals in each location listed in Table 2.5. response suggests that the CSZ probably is not the “dominant player” for tsunami haz-ards along the central California and southern California coast. While great earthquakes on the CSZ will produce significant and damaging runup in the immediate source area, the modeling shows that most of this energy is radiated offshore towards Hawaii and Japan, while relatively little wave energy is propagated south along the coast. This is also shown in the maximum transpacific wave height plots for the Cascadia subduction zone cases presented in Section 2.5. The smaller ruptures of the CSZ pose very little hazard for San Francisco Bay. The largest South American sources pose less hazard than Cascadia III (which produced the highest response among Cascadia events). A much smaller response appears to be excited by sources in the Kuril Islands and Japan. 75 |
