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Title3D ground motion in the Georgia Basin region of SW British Columbia for Pacific Northwest scenario earthquakes
AuthorMolnar, S; Cassidy, J FORCID logo; Dosso, S E; Olsen, K B
SourceProceedings of the 9th U.S. National and 10th Canadian Conference on Earthquake Engineering/Compte Rendu de la 9ième Conférence Nationale Américaine et 10ième Conférence Canadienne de Génie Parasismique; 754, 2010, 10 pages
Alt SeriesEarth Sciences Sector, Contribution Series 20090313
Meeting9th US Conference / 10th Canadian Conference on Earthquake Engineering; Toronto, ON; CA; July 25-29, 2010
RelatedThis publication is contained in Estimated seismic design values for Canadian missions abroad
ProvinceBritish Columbia
NTS92B; 92F; 92G
AreaGeorgia Basin
Lat/Long WENS-125.5000 -122.0000 50.0000 48.0000
Subjectsgeophysics; engineering geology; earthquakes; earthquake studies; earthquake mechanisms; strong motion seismology; plate motions; seismicity; s waves; seismic waves; surface wave studies; Georgia Basin
Illustrationslocation maps
ProgramPublic Safety Geoscience Targeted Hazard Assessments in Western Canada
AbstractLong-period (> 2 s) ground motions in the Georgia basin region of SW British Columbia (BC) are investigated for Pacific Northwest scenario earthquakes using 3D finite-difference simulations of viscoelastic wave propagation. The simulations are validated by comparing synthetic surface waveforms with 36 selected strong- and weak-motion recordings of the 2001 MW 6.8 Nisqually earthquake at sites spanning from Puget Sound, Washington, to southern BC. This is the first opportunity to validate the 3D geologic model of the Georgia basin region, such that the upper 1 km structure and the degree of anelastic attenuation are currently under development. Deep in-slab Juan de Fuca plate scenario earthquakes are investigated by initiating the Nisqually-model source in four different locations beneath Georgia basin in a NW-SE trending sense congruent with observed seismicity. For all deep in-slab earthquake simulations, the largest ground motions occur NW of the source location, dramatically altering the amplitude and pattern of the simulated ground motion with source location. In all cases, ground motion is predominantly amplified in the NW part of the Georgia basin as well as along a NE-SW trending velocity contrast that runs beneath the city of Vancouver. In Vancouver, the largest simulated ground motions (9.6 cm/s) from "Nisqually-type" deep in-slab earthquakes occurs when the source is located towards the southeast. Shallow crustal North America plate scenario earthquakes are being explored using slip distribution solutions from large shallow earthquakes elsewhere in the world.

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