Velocity-weakening and -strengthening friction at single and multiasperity contacts with calcite single crystals.

SignificanceThe empirical nature of rate-and-state friction (RSF) equations remains a drawback to their application to predict earthquakes. From nanoscale friction measurements on smooth and rough calcite crystals, a set of parameters is analyzed to elucidate microscopic processes dictating RSF. We infer the influence of roughness on the velocity dependence of friction in dry environment and that atomic attrition leads to stick-slip instabilities at slow velocities. In fault dynamics, stick-slip is associated with seismic slips. The aqueous environment eliminates atomic attrition and stick-slip and dissolves calcite under pressure. This yields remarkable lubrication, even more so in rough contacts, and suggests an alternative pathway for seismic slips. This work has implications for understanding mechanisms dictating fault strength and seismicity.

Citation

Binxin Fu, Rosa M Espinosa-Marzal. Velocity-weakening and -strengthening friction at single and multiasperity contacts with calcite single crystals. Proceedings of the National Academy of Sciences of the United States of America. 2022 May 31;119(22):e2112505119

PMID: 35613057

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