Understanding dynamic friction through spontaneously evolving laboratory earthquakes

Vito Rubino, Ares J. Rosakis, & Nadia Lapusta

Published June 29, 2017, SCEC Contribution #6272

Friction plays a key role in how ruptures unzip faults in the Earth’s crust and release waves that cause destructive shaking. Yet dynamic friction evolution is one of the biggest uncertainties in earthquake science. Here, we report on novel measurements of evolving local friction during spontaneously developing mini-earthquakes in the laboratory, enabled by our ultra-high-speed full-field imaging technique. The technique captures the evolution of displacements, velocities, and stresses of dynamic ruptures, whose rupture speed range from sub-Rayleigh to supershear. The observed friction has complex evolution, featuring initial velocity strengthening followed by substantial velocity weakening. Our measurements are consistent with rate-and-state friction formulations supplemented with flash heating but not with widely used slip-weakening friction laws. This study develops a new approach for measuring local evolution of dynamic friction and has important implications for understanding earthquake hazard since laws governing frictional resistance of faults are vital ingredients in physically-based predictive models of the earthquake source.

Citation
Rubino, V., Rosakis, A. J., & Lapusta, N. (2017). Understanding dynamic friction through spontaneously evolving laboratory earthquakes. Nature Communications, 8. doi: 10.1038/ncomms15991.

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