Damping values derived from surface-source, downhole-receiver measurements at 22 sites in the San Francisco Bay Area of central California and the San Fernando Valley of southern California

Bulletin of the Seismological Society of America
By: , and 

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Abstract

A method discussed in Gibbs, Boore, et al. (1994) was applied to surface‐source, downhole‐receiver recordings at 22 boreholes, in the San Francisco Bay area in central California and the San Fernando Valley of southern California, to determine the average damping ratio of shear waves over depth intervals ranging from about 10 m to as much as 245 m (at one site), with most maximum depths being between 35 and 90 m. The average damping values range from somewhat less than 1% to almost 8%, with little dependence on grain size for sites in sediments. Surprisingly, the average damping values for sites with average velocities greater than about 450  m/s450  m/s, including, but not limited to rock sites, are generally larger than for sites with lower average velocities. The combined effect of the higher damping and shorter travel times through the rock columns, however, leads to an effective attenuation that is generally comparable or smaller than for soil sites.

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Publication type Article
Publication Subtype Journal Article
Title Damping values derived from surface-source, downhole-receiver measurements at 22 sites in the San Francisco Bay Area of central California and the San Fernando Valley of southern California
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120200225
Volume 111
Issue 4
Year Published 2021
Language English
Publisher Seismological Society of America
Contributing office(s) Earthquake Science Center
Description 9 p.
First page 2158
Last page 2166
Country United States
State California
Other Geospatial San Francisco Bay Area, San Fernando Valley
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