Period‐Multiplying Cycles at the Transition Between Stick‐Slip and Stable Sliding and Implications for the Parkfield Period‐Doubling Tremors

Abstract

The recurrence patterns of the Parkfield tremors with period‐multiplying slow and fast ruptures provide new insights on the physics of earthquake cycles. However, the mechanisms behind the peculiar recurrence pattern and the coupling between slow‐slip events and seismic radiations are still unclear. Here, we conduct direct‐shear experiments on polycarbonate and granite fractures under varying stress conditions to investigate the variations of rupture properties near the stability transition. Laboratory slow and fast ruptures sequences produce slip‐predictable period‐multiplying cycles with correlative acoustic energy release, stress drop, event duration, and recurrence intervals. However, gouge accumulation by damage of the granite fracture provokes changes in stiffness and stress drops ratios over multiple cycles, affecting the recurrence intervals and energy release of consecutive slip events. These findings confirm the link between low‐frequency earthquakes and underlying slow‐slip events, with period‐multiplying cycles naturally occurring near the stability transition.

A Rate‐, State‐, and Temperature‐Dependent Friction Law With Competing Healing Mechanisms

“…The resulting complex mechanical response can be captured by empirical friction laws that employ a state variable to represent structural evolution within the fault zone (Chester, 1994; Dieterich, 1979, 1981; Ruina, 1983). The rate‐ and state‐dependent friction formulations are key to representing all stages of the seismic cycle with different rupture styles (Barbot et al., 2012, 2018, 2020, 2021; Lapusta & Barbot, 2012; Lapusta & Rice, 2003; Liu & Rice, 2005; Mei, Barbot, & Wu, 2021; Nie & Barbot, 2021; Sathiakumar & Barbot, 2021; Shi et al., 2020; Veedu & Barbot, 2016) and recurrence patterns (Cattania, 2019; Nie & Barbot, 2022).…”

Roles of Normal Stress, Roughness, and Slip Displacement in the Stability of Laboratory Fault in a Sandstone

“…In our study, fault block slip is stable when the shear stress/friction coefficient remains nearly constant after reaching its peak, and it is unstable when the stick-slip occurs with periodic up-and-down in the shear stress/friction coefficient [28,54].…”

“…The ratio between ks and kc is called t stiffness ratio. Rice [55] proposed that stiffness ratio can predict the slip state of fau When ks > kc, the fault block slip is stable; when ks < kc, the fault block slip is unstable; a when the ks and kc are close to each other, the faults behave as slow-slip faults [28,54]. T means that the fault block slip behavior spectrum is a function of the stiffness ratio, a the change trend of slip stability of faults can be reflected by the stiffness ratio.…”

Laboratory Earthquake Ruptures Contained by Velocity Strengthening Fault Patches

“…More commonly, lab experiments use a VW fault surface using rocks or plastic materials, surrounded by the free surfaces of the sample (i.e., L = total sample length). These experiments also reported fast and slow stick-slip events (Leeman et al, 2016;Mclaskey & Yamashita, 2017;Mei et al, 2021Mei et al, , 2022Yamashita et al, 2022). However, in this case, the free ends of the sample are more unstable than the interior of the sample, so the fault ends can act as asperities (Cebry et al, 2022), which does not correctly simulate natural seismic zones.…”