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Published December 2005 | Submitted + Published + Supplemental Material
Journal Article Open

Rayleigh-Wave Multipathing along the West Coast of North America


We have created a movie of surface ground motion for the 3 November 2002 Denali fault earthquake based on 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.

Additional Information

© 2005 Seismological Society of America. Manuscript received 1 September 2004. We thank Hiroo Kanamori for help in calculating the phase-velocity map and two anonymous reviewers for constructive suggestions. This research was supported in part by USGS Grant 04HQGR0048 and by the Gordon and Betty Moore Foundation. Seismic data were obtained from the Southern California Earthquake Data Center. The computations were performed at the Earth Simulator Center of JAMSTEC by Seiji Tsuboi. The figures were created with the Generic Mapping Tools (Wessel and Smith, 1998). This is Caltech Seismological Laboratory contribution 9090 and Caltech Tectonic Observatory contribution 4.

Attached Files

Published - 5E4D6A7Ed01.pdf

Submitted - ji_BSSA2005.pdf

Supplemental Material - denali_movie.mpg


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