HR: 11:40h
AN: S52B-05    [Abstracts]
TI: Rayleigh-wave multi-pathing along the west coast of North America
AU: * Ji, C
EM: jichen@gps.caltech.edu
AF: California Institute of Technology, 252-21 Caltech, Pasadena, CA 91125 United States
AU: Tsuboi, S
EM: tsuboi@jamstec.go.jp
AF: Institute for Research on Earth, EvolutionJapan Agency for Marine-Earth Science and Technology, Kanazawa-ku Yokohama, 236-0001 Japan
AU: Komatitsch, D
EM: dimitri.komatitsch@univ-pau.fr
AF: Universit‚ de Pau et des Pays de l'Adour,Avenue de l'Universit‚, Avenue de l'Universit‚ , Pau, 64013 France
AU: Tromp, J
EM: jtromp@gps.caltech.edu
AF: California Institute of Technology, 252-21 Caltech, Pasadena, CA 91125 United States
AB: We have created a movie of surface ground motions for the November 3, 2002, Denali fault earthquake based upon spectral-element simulations using crustal model CRUST2.0, mantle model S20RTS, topography and bathymetry model ETOPO5, and a finite-fault slip model. The movie features two anomalous wave packets that travel along the west coast of the North American plate following off-great-circle paths. These wave packets are Rayleigh waves with dominant periods around 20 sec, which are also found in seismograms recorded by the Southern California Seismic Network. One of these packets is the direct surface wave, whose group arrival-time changes laterally as dictated by the shape of the Oregon coast. The other packet is a surface wave reflected by a lateral interface underneath the Rocky Mountains. A linear reflector parallel to the Canadian coast offsetting it by a few hundred kilometers can explain its arrival time, but the offsetting distance derived from the synthetic seismograms puts the reflector 350 km northeast of the result obtained from the data, indicating a need to update the crustal and mantle models in this area. Records of other big earthquakes (Mw>6) are analyzed to better constrain this reflector and forward calculations using the Spectral element method (SEM) will be preformed to evaluate the final result.
DE: 7200 SEISMOLOGY
SC: Seismology [S]
MN: 2004 AGU Fall Meeting