An experimentally-based friction law for high-velocity, long-displacement slip-pulse events during earthquakes

Abstract

Large earthquakes initiate at small nucleation sites and propagate as rupture fronts along the host fault. It is inherently challenging to resolve the complexity of fault rupture at depth, and therefore, the evolution of frictional strength during earthquakes is commonly analyzed in laboratory experiments. We experimentally demonstrate here that this evolution depends simultaneously on all slip kinematic components: displacement, velocity and acceleration. We incorporate these components in shear experiments with slip-histories that resemble the theoretical expectations for earthquake slip. These experiments led to a new friction law that fits fault behavior during high-velocity/long-displacement slip. Our numerical simulations of dynamic rupture along a planar fault that obeys this friction law reproduced a range of earthquake source features including slip-pulse, Yoffe function, Gaussian velocity, and spontaneous slip arrest. Finally, we demonstrate that this experimentally-based friction law can realistically simulate the propagation and arrest of natural earthquakes.