Decadal Creep-rate Changes Along the Hayward Fault

Earthquake Science Center Seminars

Roland Burgmann, University of California Berkeley

Decadal changes in aseismic fault slip rate on partially coupled faults reflect long-term changes in fault loading and/or fault-frictional properties that can be related to earthquake cycle processes. We consider constraints on aseismic fault slip rates from historical alignment array measurements, InSAR measurements since 1992, and repeating micro-earthquakes since 1984 along the Hayward fault, California. During recent decades, creep rates consistently increased along the whole Hayward fault. Accelerated fault creep associated with M > 4 earthquakes on the northern Hayward fault in 2007, 2010 and 2018 may explain some of the creep-rate accelerations, but the acceleration on the remaining Hayward fault does not seem to be directly tied to small-scale afterslip transients. Dynamic models of partially coupled faults through earthquake cycles suggest non-stationary asperities that continue to decrease in size late in the earthquake cycle. We explore such asperity erosion models to explain the apparent decadal acceleration of aseismic Hayward fault slip.