Unraveling Scaling Properties of Slow‐Slip Events

A major debate in geophysics is whether earthquakes and slow‐slip events (SSEs) arise from similar failure mechanisms. Recent observations from different subduction zones suggest that SSEs follow the same moment‐duration scaling as earthquakes, unlike qualitatively different scaling proposed by earlier studies. Here, we examine the scaling properties using dynamic simulations of frictional sliding. The resulting sequences of SSEs match observations from the Cascadia subduction zone, including the earthquake‐like cubic moment‐duration scaling. In contrast to conventional and widely used assumptions of magnitude‐invariant rupture velocities and stress drops, both simulated and natural SSEs have rupture velocities and stress drops that increase with event magnitudes. These findings support the same frictional origin for both earthquakes and SSEs while suggesting a new explanation for the observed SSEs scaling. Plain Language Summary Tectonic faults produce a wide spectrum of slip modes, ranging from fast earthquakes to slow‐slip events. Whether slow‐slip events and regular earthquakes result from a similar physics is debated. Here we present numerical simulations to show that slow‐slip events can result from frictional sliding like seismic slip, with an additional mechanism that prevents acceleration to fast slip due to the presence of fluids. The model succeeds in reproducing a realistic sequence of slow‐slip events and provides an excellent match to the observations from the Cascadia subduction zone, including the observation that the moment, which quantifies the energy released by fault slip, is proportional to the cube of the duration. Importantly, our study demonstrates that this scaling arises for different reasons from the traditional explanation proposed for regular earthquakes. Key Points We examine the scaling properties of slow‐slip events using dynamic simulations of frictional sliding Our results match observations from the Cascadia subduction zone, including the earthquake‐like cubic moment‐duration scaling Slow‐slip events are consistent with ordinary earthquake scaling due to magnitude‐dependent rupture speed and stress drop