Fast and Slow Slip Events Emerge Due to Fault Geometrical Complexity

Active faults release elastic strain energy via a whole continuum of modes of slip, ranging from devastating earthquakes to slow slip events (SSEs) and persistent creep. Understanding the mechanisms controlling the occurrence of rapid, dynamic slip radiating seismic waves (i.e., earthquakes) or slow, silent slip (i.e., SSEs) is a fundamental point in the estimation of seismic hazard along subduction zones. Using the numerical implementation of a simple rate-weakening fault model, we show that the simplest of fault geometrical complexities with uniform rate-weakening friction properties give rise to both SSEs and fast earthquakes without appealing to complex rheologies or mechanisms. We argue that the spontaneous occurrence, the characteristics and the scaling relationship of SSEs and earthquakes emerge from geometrical complexities. The geometry of active faults should be considered as a complementary mechanism to current numerical models of SSEs and fast earthquakes.