Relationship Between Fault Creep and Shallow Stress Accumulation Rate

Fault creep, which is non-seismic movement of a fault, is important for earthquake hazard assessment but the factors controlling fault creep are not well understood. Here we investigate the hypothesis that creep rate depends on the product of shallow stress accumulation rate and the creeping depth. Stress accumulation rate at 2 km depth along the San Andreas Fault System (SAFS) is estimated from a 3-D viscoelastic model constrained by GPS observations. The creeping depth is estimated with two approaches: i) assuming a uniform depth along the entire SAFS and ii) using a depth based on the balance between model stress and fault friction. The model with a uniform creeping depth shows a good correlation with observed creep rate (0-30 mm/yr) while the correlation is poor for the model where creep rate depends on accumulated stress.