HR: 1340h
AN: S53A-1011    [Abstracts]
TI: Probabilistic Tsunami Hazard Analysis - Results for the Western United States
AU: * Thio, H
EM: hong_kie_thio@urscorp.com
AF: URS Corp, 566 El Dorado Street, Pasadena, CA 91101, United States
AU: Polet, J
EM: jpolet@csupomona.edu
AF: Dept. of Geology, California State Polytechnic University, Pomona, 3801 W. Temple Avenue, Pomona, CA 91768, United States
AU: Somerville, P
EM: paul_somerville@urscorp.com
AF: URS Corp, 566 El Dorado Street, Pasadena, CA 91101, United States
AB: We have developed a series of probabilistic tsunami hazard maps for the coasts of western North America based on fault source characterizations of the circum-Pacific subduction zones as well as local offshore faults. The maps show the probabilistic offshore exceedance waveheights at 72, 475, 975 and 2475 year return periods, which are the return periods typically used in Probabilistic Seismic Hazard Analysis (PSHA). Our method follows along similar lines as (PSHA) which has become a standard practice in the evaluation and mitigation of seismic hazard in particular with respect to structures, infrastructure and lifelines. Its ability to condense complexities, variability and uncertainties of seismic activity into a manageable set of ground motion parameters greatly facilitates the planning and design of effective seismic resistant buildings and infrastructure. Because of the strong dependence of tsunami wave heights on bathymetry, we use a full waveform tsunami waveform computation in lieu of attenuation relations that are common in PSHA. By pre-computing and storing the tsunami waveforms at points along the coast generated for sets of subfaults that comprise larger earthquake faults, we can rapidly synthesize tsunami waveforms for any slip distribution on those faults by summing the individual weighted subfault tsunami waveforms. This Green's function summation provides accurate estimates of tsunami height for probabilistic calculations, where one typically integrates over thousands of earthquake scenarios. We have carried out tsunami hazard calculations for western North America and Hawaii based on a comprehensive source model around the Pacific Ocean including both subduction zone sources as well as local offshore faults. We will present the tsunami hazard maps and discuss how these results are used for probabilistic inundation mapping, including a follow-up inundation study of the San Francisco Bay area that is based on disaggregation results of the probabilistic analysis. We will also show that even for tsunami sources with large uncertainties (e.g. submarine landslides) a probabilistic framework can yield meaningful and consistent results.
DE: 0468 Natural hazards
DE: 1734 Seismology
DE: 4564 Tsunamis and storm surges
SC: Seismology [S]
MN: 2007 Fall Meeting