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GEOREF RECORD

Ground-motion attenuation in the Sacramento-San Joaquin Delta, California, from 14 Bay area earthquakes, including the 2014 M 6.0 South Napa earthquake

Jemile E. Erdem, John Boatwright and Jon B. Fletcher
Ground-motion attenuation in the Sacramento-San Joaquin Delta, California, from 14 Bay area earthquakes, including the 2014 M 6.0 South Napa earthquake
Bulletin of the Seismological Society of America (April 2019) 109 (3): 1025-1033

Abstract

Peak ground motions (acceleration and velocity) radiated by earthquakes in the San Francisco Bay area and recorded within the Sacramento-San Joaquin Delta generally attenuate faster with distance than the Next Generation Attenuation-West2 ground-motion prediction equations (GMPEs). We evaluate the attenuation for a wide set of paths into the Delta by analyzing recorded ground motions from fourteen 4< or =M<7 earthquakes located on major Bay area faults: the San Andreas, Calaveras, Hayward, West Napa, and Green Valley faults. We select stations within azimuthal ranges of 38 degrees -114 degrees into the Delta and calculate the residuals of the peak ground motions relative to the Boore et al. (2014) GMPEs. We then fit the natural log of these peak ground acceleration and peak ground velocity residuals for each earthquake to the function a-krgamma , in which a is an event term and krgamma is the differential attenuation. Although there is some variation in the differential attenuation obtained for each earthquake, the peak ground motions from most of the 14 events attenuate faster than predicted by the Boore et al. (2014) GMPEs. The differential attenuation does not appear to depend on azimuth or magnitude of the earthquake; however, earthquake depth may have an effect. Our results suggest that attenuation models for the Delta can be significantly improved through regionalization, although this regionalization will increase the model complexity and the epistemic uncertainty.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 109
Serial Issue: 3
Title: Ground-motion attenuation in the Sacramento-San Joaquin Delta, California, from 14 Bay area earthquakes, including the 2014 M 6.0 South Napa earthquake
Affiliation: U. S. Geological Survey, Earthquake Science Center, Menlo Park, CA, United States
Pages: 1025-1033
Published: 20190416
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 19
Accession Number: 2019-037997
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch map
N37°00'00" - N39°00'00", W123°00'00" - W121°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201920
Program Name: USGSOPNon-USGS publications with USGS authors
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