Fault resonance process and its implications on seismicity modulation on the active fault system

Abstract

Various periodic external loading processes (e.g., snow, hydrological and atmospheric, earth tide and surface reservoir load, etc.) affect tectonic deformation and sometimes modulate seismicity in diverse tectonic settings. Small stress variations induced by external loads may influence the fault dynamics and destabilize fault zones. In this article, we report five cases of earthquake occurrence in the plate boundary and plate interior regions where such a destabilization seems to be operating. We test the possibility of resonance amplification assuming rate-and-state friction and look for the model parameters that could justify resonance destabilization. We find that frictional resonance destabilization is possible in regions that are near the stability boundary (velocity neutral areas). The critical slip distance for the evolution of friction is similar to laboratory estimates. In some cases, effective normal stress lower than the lithostatic stress have to be assumed for the model to be consistent with the observations, implying high pore pressure. We propose that crustal faults of conditionally stable frictional domains with anomalous pore pressure are sensitive to periodic stress perturbations by the external loading process.