Origins of roughness evolution and strategies for its implementation on rate-state faults

Enrico Milanese, Tobias Brink, Ramin Aghababaei, Jean-François Molinari, & Camilla Cattania

Published August 11, 2021, SCEC Contribution #11254, 2021 SCEC Annual Meeting Poster #136 (PDF)

Friction and wear are physical phenomena that emerge upon sliding of one surface against another. They are thus found in a wide variety of setups and at all scales -- from geological faults to nanoscale engineering applications. A key role in the frictional response of all these systems is played by surface roughness, which is often observed to be fractal. In particular, faults are the frictional surfaces that exhibit fractality over the largest number of scales, from fractions of millimeters to thousands of kilometers.

Yet, it is still poorly understood how and why the fractal geometry emerges and how roughness affects the frictional response of a system, and in particular how faults evolve through wear processes.

Here, by means of extensive atomistic simulations, we first show the role of third body (gouge), interfacial adhesion, and scale-dependent deformation mechanisms in driving a model system to exhibit the observed fractal morphology. The results complement recent findings suggesting that the fractality of faults is linked to the rock strength being scale-dependent. We also briefly address a mechanical model for third body growth which can inspire further investigations in fault wear and roughness evolution.

Finally, building upon these observations, we present ongoing developments in the modelling of roughness evolution in rate-state faults within a quasi-dynamic boundary element code.

Key Words
roughness rate-state boundary element

Citation
Milanese, E., Brink, T., Aghababaei, R., Molinari, J., & Cattania, C. (2021, 08). Origins of roughness evolution and strategies for its implementation on rate-state faults. Poster Presentation at 2021 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)