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Ubiquitous Earthquake Dynamic Triggering in Southern California
  • Nicolas D DeSalvio,
  • Wenyuan Fan
Nicolas D DeSalvio
Scripps Institution of Oceanography, UCSD

Corresponding Author:ndesalvio@ucsd.edu

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Wenyuan Fan
Scripps Institution of Oceanography, UCSD
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Earthquakes can be dynamically triggered by the passing waves of events from disconnected faults. The frequent occurrence of dynamic triggering offers tangible hope in revealing earthquake nucleation processes. However, the physical mechanisms behind earthquake dynamic triggering have remained unclear, and contributions of competing hypotheses are challenging to isolate with individual case studies. Therefore, developing a systematic understanding of the spatiotemporal patterns of dynamic triggering can provide insights into the physical mechanisms, which may aid mitigation of earthquake hazards. Here we investigate earthquake dynamic triggering in Southern California from 2008 to 2017 using the Quake Template Matching catalog and an approach free from assuming an earthquake occurrence distribution. We develop a new set of statistics to examine the significance of seismicity-rate changes as well as moment-release changes. We show that up to 70% of global M≥6 events may have triggered earthquakes in southern California and that the triggered seismicity often occurred several hours after the passing seismic waves. On average, earthquakes are triggered about every 4 days in the region, albeit at different locations. Although adjacent fault segments can be triggered by the same earthquakes, the majority of triggered earthquakes seem to be uncorrelated, suggesting that the process is primarily governed by local conditions. Further, the occurrence of dynamic triggering does not seem to correlate with ground motion (e.g., peak ground velocity) at the triggered sites. These observations indicate that nonlinear processes may have primarily regulated the dynamic triggering cases.
03 Feb 2023Submitted to ESS Open Archive
09 Feb 2023Published in ESS Open Archive