Rapid Fault Healing After Seismic Slip

Abstract

Faults slip suddenly during earthquakes, accelerating to velocities on the order of a few meters per second. At these seismic slip velocities, a significant reduction in fault strength occurs (Di Toro et al., 2011) as a result of various dynamic weakening mechanisms becoming activated by shear heating and/or grain size reductions (Tullis, 2015). Although our knowledge of dynamic fault weakening processes has increased significantly over the last 25 years since the advent of high-velocity friction experiments (Tsutsumi & Shimamoto, 1997), our understanding of how faults regain their strength after dynamic weakening, once seismic slip has ceased, is more limited. Fault restrengthening is a fundamental process in the earthquake cycle that may control the recurrence time (Vidale et al., 1994), the mode of slip (Shreedharan et al., 2023), the maximum strength that can be attained (Kanamori & Allen, 1986;Scholz et al., 1986), and the nature of radiated energy (McLaskey et al., 2012) in future events.The rate of fault restrengthening can vary with both time and space along a fault during the earthquake cycle (Li et al., 2006;Pei et al., 2019). Restrengthening may occur initially during coseismic slip itself, as sometimes observed during the deceleration phase of high-velocity friction experiments (e.g.,

Investigating Dynamic Weakening in Laboratory Faults Using Multi‐Scale Flash Heating Coupled With mm‐Scale Contact Evolution

“…When using a single set of constitutive parameters to describe and model a wide range of experiment conditions, some outstanding transient and hysteretic weakening is to be expected, however the model fits are not presently sufficient to definitively establish these parameters as representative for Westerly granite. Incorporating healing processes related to chemical bonding at asperity contacts (Bedford et al., 2023) or water related healing (Violay et al., 2019) into the restrengthening phases of sliding may improve fits during the deceleration phase. Additionally, descriptions of frictional behavior during all phases of sliding may be improved by (a) further incorporating wear processes, or the effects of wear processes, into constitutive equations for dynamic weakening including flash heating and weakening and (b) considering dynamic weakening mechanisms occurring at the mm‐scale or larger.…”

Multiple Seismic Slip‐Rate Pulses and Mechanical and Textural Evolution of Calcite‐Bearing Fault Gouges

“…In the bare‐rock surface samples experiments, we imposed one slip‐rate pulse. In the gouge layer experiments, we imposed up to four slip‐rate pulses, with a holding time between slip‐rate pulses of 120 s. This holding time was chosen to avoid effect of rapid healing on the gouge material due to temperature increase during sliding (Bedford et al., 2023; Yao et al., 2013) and sufficiently short for the static postseimic healing to not be relevant (Chen et al., 2015). Mechanical data (axial load, torque, axial displacement and angular rotation) were acquired at a frequency between 4 Hz (hold time) and 12.5 kHz (slip‐rate pulse).…”

“…Moreover, Han et al (2010) showed a decrease of the slip necessary to reach steady state friction in the second slip pulse. Finally, several works focused on the restrengthening and the healing rate after the shearing at coseismic slip-rate of natural gouge (Yao et al, 2013) or gabbro (Mizoguchi et al, 2009) and granite (Bedford et al, 2023). All these works evidenced a rapid healing due to the dissipation of the heat produced during the fault shearing at seismic slip-rates.…”