Surface wave triggering of earthquakes and non-volcanic tremor: Insights into the physics of rupture

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This proposal outlines detailed analyses and modeling of surface waves in relation to triggering of both earthquakes and non-volcanic tremor. In particular, we have two main hypotheses that we will test: 1) the orientation of the local stress field and the orientation of the transient stresses induced by the surface waves combine to generate failure and 2) triggered earthquakes and triggered non-volcanic tremor exhibit similar failure mechanisms caused by transient stress fluctuations. We will test these two hypotheses by analyzing numerous large (M 7.0) earthquakes in regions with good local/regional network coverage, local/regional catalogs, and with documented triggered earthquakes and NVT. We will also develop a simple failure model that can explain our observations of triggered earthquakes and NVT. Our results will provide fundamental insight into stresses that trigger events, and whether these two seemingly different processes are indeed similar. Closely studying surface waves and triggering holds the key for understanding the physics of rupture.A growing body of scientific studies has demonstrated that the passage of transient signals, or seismic waves, from large earthquakes can remotely trigger small earthquakes and non-volcanic tremor thousands of kilometers from an epicenter of a large earthquake. These two phenomena, at first glance, appear quite different, with the only common attribute being the triggering stress: surface waves. Triggered non-volcanic tremor (NVT) is the radiation of non-impulsive seismic energy not associated with volcanic processes that occurs coincidentally with the passage of the surface waves of a larger earthquake; similarly, dynamically triggered earthquakes are generally small earthquakes that trigger coincidentally or shortly after the arrival of surface waves from a larger earthquake. Given the fact that these two triggered phenomena occur on a frequent basis, a detailed investigation into both the local and triggering, transient stress fields could provide fundamental insight into the physical mechanisms of rupture failureThis project will gain fundamental insight into dynamically triggered earthquakes and non-volcanic tremor, one of the most intriguing discoveries in earthquake science that has occurred in the past 8 years. Results of the project will be published in peer-reviewed journals and presented at national conferences to share with the scientific community. Furthermore, the University of Texas at El Paso is a Hispanic Serving Institute (HSI) and we will actively recruit undergraduate and graduate students, plus a postdoctoral scholar from underrepresented groups to participate in this project.