HR: 1330h
AN: S12A-0366    [PDF]
TI: Broadband Modeling of the 2002 Denali, Alaska, Earthquake on the Earth Simulator
AU: * Tsuboi, S
EM: tsuboi@jamstec.go.jp
AF: Institute for Frontier Research on Earth Evolution, Japan Marine Science and Technology Center, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001 Japan
AU: Komatitsch, D
EM: komatits@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 United States
AU: Ji, C
EM: jichen@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 United States
AU: Tromp, J
EM: jtromp@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 United States
AB: We use a Spectral-Element Method implemented on the Earth Simulator in Japan, to simulate broadband seismic waves generated by the November 3, 2002, Denali, Alaska, earthquake. The source model is constrained by teleseismic body waves and observed surface offsets. The earthquake was initiated by a small thrust event, and is well characterized by a 5-segment fault geometry dominated by right-lateral rupture along 220 km of the Denali fault. To use the finite fault model in our numerical simulations we approximate it by a set of 475 sub-events of size 4 km X 5 km; these sub-events represent the distribution of the moment-density tensor. We perform the three-dimensional numerical simulations, which incorporate 3D variations in compressional wave speed, shear-wave speed and density, attenuation, anisotropy, ellipticity, topography and bathymetry, and crustal thickness. We use model S20RTS of the mantle (Ritsema et al., 1999), model CRUST2.0 of the crust (Basin et al., 2000), and topography and bathymetry model ETOPO5. The simulations are performed on 1944 processors, which require 243 out of 640 nodes of the Earth Simulator. We use a mesh with 82 million spectral-elements, for a total of 5467 million global integration grid points (i.e., almost 15 billion degrees of freedom). This translates into an approximate grid spacing of 2.9 km along the Earth's surface. On this number of nodes, a simulation of 60 minutes of wave propagation accurate at periods of 5 seconds and longer requires about 15 hours of CPU time. The results of the simulation reveal significantly enhanced ground motions toward the conterminous United States for both body and surface waves. For reference, the same data are compared against SEM synthetics for 1D model PREM. The results show that the transverse component of SEM synthetics fit significantly better by the 3D model.
DE: 7203 Body wave propagation
DE: 7209 Earthquake dynamics and mechanics
DE: 7255 Surface waves and free oscillations
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting