Tidal triggering of earthquakes suggests poroelastic behavior on the San Andreas Fault

Earth and Planetary Science Letters
By: , and 



Tidal triggering of earthquakes is hypothesized to provide quantitative information regarding the fault's stress state, poroelastic properties, and may be significant for our understanding of seismic hazard. To date, studies of regional or global earthquake catalogs have had only modest successes in identifying tidal triggering. We posit that the smallest events that may provide additional evidence of triggering go unidentified and thus we developed a technique to improve the identification of very small magnitude events. We identify events applying a method known as inter-station seismic coherence where we prioritize detection and discrimination over characterization. Here we show tidal triggering of earthquakes on the San Andreas Fault. We find the complex interaction of semi-diurnal and fortnightly tidal periods exposes both stress threshold and critical state behavior. Our findings reveal earthquake nucleation processes and pore pressure conditions – properties of faults that are difficult to measure, yet extremely important for characterizing earthquake physics and seismic hazards.

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Publication type Article
Publication Subtype Journal Article
Title Tidal triggering of earthquakes suggests poroelastic behavior on the San Andreas Fault
Series title Earth and Planetary Science Letters
DOI 10.1016/j.epsl.2016.12.014
Volume 460
Year Published 2017
Language English
Publisher Elsevier
Contributing office(s) Earthquake Science Center
Description 7 p.
First page 164
Last page 170
Country United States
State California
Other Geospatial San Andreas Fault
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