Seismic attenuation monitoring of a critically stressed San Andreas fault

Geophysical Research Letters
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Abstract

We show that seismic attenuation ( urn:x-wiley:00948276:media:grl61586:grl61586-math-0001) along the San Andreas fault (SAF) at Parkfield correlates with the occurrence of moderate‐to‐large earthquakes at local and regional distances. Earthquake‐related urn:x-wiley:00948276:media:grl61586:grl61586-math-0002 anomalies are likely caused by changes in permeability from dilatant static stress changes, damage by strong shaking from local sources, and pore unclogging/clogging from mobilization of colloids by dynamic strains. We find that, prior to the 2004 M6 Parkfield earthquake, prefailure conditions for some local events of moderate magnitude correspond to positive anomalies of urn:x-wiley:00948276:media:grl61586:grl61586-math-0003 on the Pacific side, with local and regional earthquakes producing sharp attenuation reversals. After the 2004 Parkfield earthquake, we see higher urn:x-wiley:00948276:media:grl61586:grl61586-math-0004 anomalies along the SAF, but low sensitivity to local and regional earthquakes, probably because the mainshock significantly altered the permeability state of the rocks adjacent to the SAF, and its sensitivity to earthquake‐induced stress perturbations.

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Publication type Article
Publication Subtype Journal Article
Title Seismic attenuation monitoring of a critically stressed San Andreas fault
Series title Geophysical Research Letters
DOI 10.1029/2020GL089201
Volume 47
Issue 23
Year Published 2020
Language English
Publisher American Geophysical Union
Contributing office(s) Pacific Coastal and Marine Science Center
Description 11 p.
Country United States
State California
Other Geospatial San Andreas Fault-Parkfield Area
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