Simulating Short-Term Evolution of Slow Slip Influenced by Fault Heterogeneities and Tides

Abstract

In this study, we analyze high-resolution tremor catalogs from northern Cascadia, Guerrero, and northern Kii Peninsula. We find that tremor often occurs in short bursts that repeatedly occupy the same source area within a slow slip event. We hypothesize that these bursts are driven by loading from slow slip in areas surrounding the tremor zone. Adopting a rate-and-state friction law with a velocity-weakening to velocity-strengthening transition, we develop a finite fault model in which the size of the slow slip zone is larger than that of the tremor zone. Tidal forcing is added. Many asperities are randomly distributed within the tremor zone in order to generate burst-like slip evolution while maintaining reasonable propagation speeds of the main slow slip front. We successfully reproduce the increasing recurrence intervals of the bursts as the main front moves across the tremor zone, as well as tidally modulated secondary fronts well behind the main front.