Linking earthquake magnitude-frequency statistics and stress in visco-frictional fault zone models

Abstract

The ability to estimate the likelihood of particular earthquake magnitudes occurring in a given region is critical for seismic hazard assessment. Earthquake size and recurrence statistics have been empirically linked to stress state, however there is ongoing debate as to which fault-zone processes are responsible for this link. We numerically model combined viscous creep and frictional sliding of a fault-zone, where applied shear stress controls the interplay between these mechanisms. This model reproduces the stress-dependent earthquake magnitude distribution observed in nature. At low stress, many fault segments creep and impede ruptures, limiting earthquake sizes. At high stress, more segments are close to frictional failure and large earthquakes are more frequent. Contrasts in earthquake statistics between regions, with depth and through time, may be explained by stress variation, which could be used in the future to further constrain probabilistic models of regional seismicity.