Ground motion in the presence of complex Topography II: Earthquake sources and 3D simulations

Bulletin of the Seismological Society of America
By: , and 

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Abstract

Eight seismic stations were placed in a linear array with a topographic relief of 222 m over Mission Peak in the east San Francisco Bay region for a period of one year to study topographic effects. Seventy‐two well‐recorded local earthquakes are used to calculate spectral amplitude ratios relative to a reference site. A well‐defined fundamental resonance peak is observed with individual station amplitudes following the theoretically predicted progression of larger amplitudes in the upslope direction. Favored directions of vibration are also seen that are related to the trapping of shear waves within the primary ridge dimensions. Spectral peaks above the fundamental one are also related to topographic effects but follow a more complex pattern. Theoretical predictions using a 3D velocity model and accurate topography reproduce many of the general frequency and time‐domain features of the data. Shifts in spectral frequencies and amplitude differences, however, are related to deficiencies of the model and point out the importance of contributing factors, including the shear‐wave velocity under the topographic feature, near‐surface velocity gradients, and source parameters.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Ground motion in the presence of complex Topography II: Earthquake sources and 3D simulations
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120160159
Volume 107
Issue 1
Year Published 2017
Language English
Publisher Seismological Society of America
Contributing office(s) Geologic Hazards Science Center
Description 15 p.
First page 344
Last page 358
Country United States
State California