Fig. 9: Responses of faults to earthquakes at multiple scales.
From: Coupled evolution of seismicity and permeability in fault zones
a Phase offsets of earth tide water well responses show a sharp change (locations at the dashed line) concurrent with the timing of far-field earthquakes, indicating increased permeability of the hydrologic system1. Dashed line a shows the 1991 Sierra Madre earthquake, and line b shows the 1995 Joshua Tree earthquake1. b Reactivation of laboratory faults and measured increase in permeability showing larger increase in post-reactivation permeability for extended hold times of 104s (circle 8) versus short hold times of 101s (circle 1)205. c Reductions in seismic velocity concurrent with the seismic cycle indicate potential elastic softening effects on the San Andreas fault following two earthquakes and subsequent tremor rates caused by seismic perturbations. These remain for 3 years but decline over time202. d Changes in wave speed measured on laboratory faults in transiting the seismic cycle204.
