Effects of Humidity, Shear Stress, and Strain Rate Localization on Fault Healing and Friction

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Marone EAR-0001215 The seismic cycle requires that faults re-strengthen between earthquakes. Frictional healing (as evidenced by increasing static friction during quasi-stationary contact) is considered the most likely mechanism of interseismic strength recovery. However, the mechanisms of frictional healing are poorly understood. This proposal is to study the physical and chemical mechanisms of fault healing and frictional aging in simulated granular fault gouge. The results of the experiments will have significant implications for understanding the distinction between time- and slip-dependent friction evolution. Recent theoretical studies of dynamic rupture indicate that this distinction plays a key role in determining seismic characteristics such as frequency-magnitude scaling and the mode of rupture expansion (as a classical, self-similar crack or a self-healing slip pulse). Thus, the results will connect in an important way to other studies of earthquake source physics including theoretically-based studies and those based on field observations.