Friday Seminar (1 July 2022) Sylvain Barbot (USC)

Title: Temperature-dependence of rate- and state-dependent friction with competing healing mechanisms

Abstract: The constitutive behavior of faults is central to many interconnected aspects of earthquake science, from fault dynamics to induced seismicity, to seismic hazards characterization. Yet, a friction law applicable to the wide range of hydrothermal conditions found in the brittle crust is still missing. Here, we investigate the effect of competing healing mechanisms on the evolution of frictional properties with temperature. The yield strength depends on the real area of contact, which is modulated by the competition between the growth and erosion of interfacial micro-asperities. Incorporating multiple healing mechanisms with different thermodynamic properties allows a transition between velocity-weakening and velocity-strengthening at steady-state with varying temperatures. We compare the physical model with the frictional parameters of granite (Mitchell et al. 2016), shale (An et al. 2020), augite (Tiang & He 2019), hornblende (Liu & He 2020), and fault gouge from the Longitudinal Valley Fault and Alpine Fault (den Hartog et al. 2021; Valdez et al 2019). The physical model may prove most relevant when the temperature evolves dynamically due to shear heating, heat and fluid transport, and metamorphism.