Repeating microearthquake sequences interact predominantly through postseismic slip

Semechah K. Lui, & Nadia Lapusta

Published 2016, SCEC Contribution #6099

Studying small repeating earthquakes enables better understanding of fault physics and characterization of fault friction properties. Some of the nearby repeating sequences appear to interact, such as the "San Francisco" and "Los Angeles" repeaters on the creeping section of the San Andreas Fault. It is typically assumed that such interactions are induced by static stress changes due to coseismic slip. Here we present a study of the interaction of repeating earthquakes in the framework of rate-and-state fault models using state-of-the-art simulation methods that reproduce both realistic seismic events and long-term earthquake sequences. Our simulations enable comparison among several types of stress transfer that occur between the repeating events. Our major finding is that postseismic creep dominates the interaction. As a result, earthquake triggering in our simulation occurs at distances much larger than typically assumed. Our findings open a possibility of using interaction of repeating sequences to estimate friction properties of creeping segments.

Lui, S. K., & Lapusta, N. (2016). Repeating microearthquake sequences interact predominantly through postseismic slip. Nature Geoscience,.