Oral Presentation

SCEC’s expansion to the full transform plate boundary brings into its purview many additional faults that slip aseismically (“creep”) during the interseismic period. In most cases, we understand these faults to be partially creeping and partially locked and therefore capable of producing hazardous earthquakes. For instance, the Hayward fault in the San Francisco Bay Area creeps heterogeneously along its length but generated the devastating 1868 M6.8 earthquake and is considered one of the most hazardous faults in the nation today. USGS and academic scientists have monitored California’s creeping faults with alignment arrays and creepmeters for over four decades, constituting one of the longest geodetic time series in the world. More recently, GNSS and InSAR have further illuminated the prevalence of fault creep in California by extensively mapping its spatial extent and temporal variation. Despite this, we still have fundamental questions about why faults creep, the basic characteristics of this process, and how this behavior affects the seismic and postseismic hazard potential of a fault system. For instance, in terms of pure process, is the occurrence of creep better explained by fault zone rheological properties or fault network geometry? In terms of hazards, under what conditions will an earthquake rupture penetrate into a creeping patch? Improving this understanding will directly benefit seismic hazard models, including the Earthquake Rupture Forecast of the National Seismic Hazard Model, that currently reduce the seismic moment rate available based on the inferred creep distribution.

In this talk, I will present examples from our team’s work and from the broader community to motivate potentially fruitful research targets related to creeping faults. The expansion of SCEC provides an exciting opportunity for the community to advance basic knowledge of fault creep processes. While valuable unto itself, this is also a necessary step to accurately forecasting how partially creeping faults will behave during earthquakes.