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Integrated Static and Dynamic Stress Models for Investigating Tremor Source Regions

Hector Gonzalez-Huizar, Sandra Hardy, Aaron A. Velasco, Bridget R. Smith-Konter, & Karen M. Luttrell

Published 2015, SCEC Contribution #6063

For active tectonic boundaries, the probability of having an earthquake along a locked zone may depend on the physical conditions at depth, including the frictional and stress state of the underlain aseismic zone; however, frictional and stress states remain difficult to estimate at deep crustal depths. Recent studies have shown that in many tectonic environments, including the San Andreas Fault (SAF) system, dynamic stresses related to the passing of seismic waves can change local stresses at deep overstressed fault patches, causing sliding and generating seismically detectable tectonic non-volcanic tremor signals. In this work, we present some of our results of using integrated models of the local static and dynamic triggering stresses to investigate the frictional and stress conditions of the SAF where ambient and triggered tremor occurs. Dynamic stress is modeled directly from recorded seismic signals, and static stress is obtained and modeled from existing SCEC Community Stress Model (CSM) contributions. The calculated triggering dynamic stress are added to static stress maps as a proxy to the absolute stresses acting during fault sliding, which is expressed as a seismically detectable tremor signal. Calculating static and dynamic stress for the entire SAF allows for a comparison of the stress and frictional conditions necessary for tremor occurrence.

Gonzalez-Huizar, H., Hardy, S., Velasco, A. A., Smith-Konter, B. R., & Luttrell, K. M. (2015). Integrated Static and Dynamic Stress Models for Investigating Tremor Source Regions. Poster Presentation at 2015 SCEC Annual Meeting.

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Earthquake Forecasting and Predictability