HR: 0800h
AN: S21A-0232    [Abstracts]
TI: Bounding Ground Motions for Hayward Fault Scenario Earthquakes Using Suites of Stochastic Rupture Models
AU: * Rodgers, A J
EM: rodgers7@llnl.gov
AF: Earth Sciences Division, Lawrence Livermore National Laboratory, L-205, Livermore, CA 94551, United States
AU: Xie, X
EM: xie@es.ucsc.edu
AF: Institute of Geophysics and Planetary Physics, University of California at Santa Cruz, 1156 High Street, Santa Curz, CA 95064, United States
AU: Petersson, A
EM: andersp@llnl.gov
AF: Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, L-550, Livermore, CA 94551, United States
AB: The next major earthquake in the San Francisco Bay area is likely to occur on the Hayward-Rodgers Creek Fault system. Attention on the southern Hayward section is appropriate given the upcoming 140th anniversary of the 1868 M 7 rupture coinciding with the estimated recurrence interval. This presentation will describe ground motion simulations for large (M > 6.5) earthquakes on the Hayward Fault using a recently developed elastic finite difference code and high-performance computers at Lawrence Livermore National Laboratory. Our code easily reads the recent USGS 3D seismic velocity model of the Bay Area developed in 2005 and used for simulations of the 1906 San Francisco and 1989 Loma Prieta earthquakes. Previous work has shown that the USGS model performs very well when used to model intermediate period (4-33 seconds) ground motions from moderate (M ~ 4-5) earthquakes (Rodgers et al., 2008). Ground motions for large earthquakes are strongly controlled by the hypocenter location, spatial distribution of slip, rise time and directivity effects. These are factors that are impossible to predict in advance of a large earthquake and lead to large epistemic uncertainties in ground motion estimates for scenario earthquakes. To bound this uncertainty, we are performing suites of simulations of scenario events on the Hayward Fault using stochastic rupture models following the method of Liu et al. (Bull. Seism. Soc. Am., 96, 2118-2130, 2006). These rupture models have spatially variable slip, rupture velocity, rise time and rake constrained by characterization of inferred finite fault ruptures and expert opinion. Computed ground motions show variability due to the variability in rupture models and can be used to estimate the average and spread of ground motion measures at any particular site. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No.W-7405-Eng-48. This is LLNL contribution UCRL- ABS-234222
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting