Laboratory Earthquakes: The Sub-Rayleigh–to–Supershear Rupture Transition

We report on the experimental observation of spontaneously nucleated supershear rupture and on the visualization of sub-Rayleigh–to–supershear rupture transitions in frictionally held interfaces. The laboratory experiments mimic natural earthquakes. The results suggest that under certain conditions supershear rupture propagation can be facilitated during large earthquake events