Understanding the failure of frictional interfaces and its spatiotemporal structure is crucial for our fundamental understanding of earthquakes. In the laboratory, we mimic ruptures along natural faults by performing dynamic stick-slip experiments along quasi one-dimensional spatially extended interfaces. We perform simultaneous measurements (at μsec time scale) of the real area of contact together with corresponding real-time (μsec time scale) measurements of spatial profiles of all stress components adjacent to the interface. These measurements enable us to uncover the breakdown process near the tip of the slipping zone for rapidly propagating ruptures. The ruptures studied in this work range from slow rupture fronts (approximately 1% of the Rayleigh wave speed) to the Rayleigh wave speed.
We will demonstrate that failure of frictional interfaces is governed by well-defined fracture processes. For the vast range of rupture velocities many nontrivial features of the stress fields observed in the experiment can be quantitatively described by classic linear elastic fracture mechanics (LEFM). We will show, however, that aspects of these solutions systematically fail to describe very rapid ruptures that asymptotically approach the Rayleigh wave speed.