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Preliminary simulation of a M6.5 earthquake on the Seattle Fault using 3D finite-difference modeling

Open-File Report 2000-339

By:
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Abstract

A three-dimensional finite-difference simulation of a moderate-sized (M 6.5) thrust-faulting earthquake on the Seattle fault demonstrates the effects of the Seattle Basin on strong ground motion in the Puget lowland. The model area includes the cities of Seattle, Bremerton and Bellevue. We use a recently developed detailed 3D-velocity model of the Seattle Basin in these simulations. The model extended to 20-km depth and assumed rupture on a finite fault with random slip distribution. Preliminary results from simulations of frequencies 0.5 Hz and lower suggest amplification can occur at the surface of the Seattle Basin by the trapping of energy in the Quaternary sediments. Surface waves generated within the basin appear to contribute to amplification throughout the modeled region. Several factors apparently contribute to large ground motions in downtown Seattle: (1) radiation pattern and directivity from the rupture; (2) amplification and energy trapping within the Quaternary sediments; and (3) basin geometry and variation in depth of both Quaternary and Tertiary sediments

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Preliminary simulation of a M6.5 earthquake on the Seattle Fault using 3D finite-difference modeling
Series title:
Open-File Report
Series number:
2000-339
Edition:
-
Year Published:
2000
Language:
ENGLISH
Publisher:
U.S. Dept. of the Interior, U.S. Geological Survey,
Description:
NA