Seismogenic and tremorgenic slow slip near the stability transition of frictional sliding

Abstract

Slow-slip events and tremors occur below the seismogenic zone of major plate boundaries. While the physics of aseismic slow-slip events is relatively well understood, the mechanics of seismogenic slow slip remains elusive because the conditions leading to slow or fast ruptures are thought to be mutually exclusive. Here, we explore fault dynamics in the parametric space of frictional conditions to show that seismogenic slow-slip events are the natural behavior of homogeneous faults, as long as the velocity dependence approaches velocity neutral with a small characteristic nucleation size. Tremors can originate from rapid bursts of slow earthquakes that are triggered as the slow-slip rupture spreads over small-scale asperities. The near velocity-neutral conditions explain the underlying mechanics of collocated slow and fast slip of seismogenic slow-slip events commonly found below the seismogenic zone. The presence of material heterogeneity may explain the spatio-temporal clustering and migration features of tremor activity.