LAUSR

Abstract Recent studies on natural and experimental seismic faults have revealed that frictional heating plays an important role in earthquake dynamics. We report changes in the optically stimulated luminescence (OSL)/thermo-luminescence (TL) and electron spin resonance (ESR) signals in quartz fault gouge (grain size 90–250 μm, given dose 40 ± 5 Gy) after frictional experiments. Our results indicate that high-rate (2.0 m/s) frictional heating during seismic events can reset the 'geologic clocks' of fault rocks. Thus, the OSL/TL/ESR signal in quartz from natural fault zones has the potential to directly constrain the age of seismic events. Whereas low-rate (2.0 mm/s) frictional slip, even over long times (1000 s), does not reset the OSL/TL signals in quartz. However, low-rate slip can reset the Al center ESR signal, but not the E’ center signal.