The Effect of flash heating on earthquake sequences and ductile shear zone structure

Kali L. Allison, & Laurent G. Montesi

Published September 11, 2022, SCEC Contribution #12554, 2022 SCEC Annual Meeting Poster #176 (PDF)

High-velocity rock friction experiments demonstrate that at high slip velocities dynamic weakening processes are activated, causing the frictional resistance of faults to drop to very low values. This reduction in frictional resistance in turn reduces the coseismic frictional heat generation of the fault. It also allows the fault to operate at lower background stress levels, which reduces the cycle-averaged thermal anomaly from frictional heat generation. Additionally, dynamic weakening enables earthquakes to propagate further into velocity-strengthening regions, potentially leading to much deeper down-dip rupture propagation limits. There are a number of different dynamic weakening mechanisms, including thermal pressurization and flash heating. I focus on flash heating, in which high slip velocities during an earthquake cause local temperature increases at asperity contacts, weakening the asperities and leading to a macroscopic drop in frictional strength. Using the code, SCycle, I explore the effect of flash heating on earthquake cycles on a vertical strike-slip fault in 2D. When simulations are performed with elastic bulk material, flash heating produces earthquakes that rupture a larger portion of the fault and that occur more infrequently. Each of these effects makes the earthquakes larger. I am currently performing simulations with power-law viscoelastic bulk material, and will compare the resulting earthquakes and shear zone structure.

Key Words
dynamic weakening, earthquake cycles, simulation

Citation
Allison, K. L., & Montesi, L. G. (2022, 09). The Effect of flash heating on earthquake sequences and ductile shear zone structure. Poster Presentation at 2022 SCEC Annual Meeting.

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