Abstract:

Natural faults are intrinsically heterogeneous where jogs, edges and steps are common. We experimentally explore how fault edges may affect earthquake and slip dynamics by applying shear to the edge of one of two flat blocks in frictional contact. We show that slip occurs via a sequence of rapid rupture events that arrest after a finite distance. Successive events extend the slip size, transfer the applied shear across the block, and cause progressively larger changes of the contact area along the contact surface. Each sequence of events dynamically forms an asperity near the edge and largely reduces the contact area beyond. These sequences of rapid events all culminate in slow slip events that lead to major, unarrested slip along the entire contact surface. These results show that a simple deviation from uniform shear loading configuration can significantly and qualitatively affect both earthquake nucleation processes and the evolution of fault complexity.