The influence of the brittle-ductile transition zone on aftershock and foreshock occurrence

Abstract

Aftershock occurrence is characterized by scaling behaviors with quite universal exponents. At the same time, deviations from universality have been proposed as a tool to discriminate aftershocks from foreshocks. Here we show that the change in rheological behavior of the crust, from velocity weakening to velocity strengthening, represents a viable mechanism to explain statistical features of both aftershocks and foreshocks. More precisely, we present a model of the seismic fault described as a velocity weakening elastic layer coupled to a velocity strengthening visco-elastic layer. We show that the statistical properties of aftershocks in instrumental catalogs are recovered at a quantitative level, quite independently of the value of model parameters. We also find that large earthquakes are often anticipated by a preparatory phase characterized by the occurrence of foreshocks. Their magnitude distribution is significantly flatter than the aftershock one, in agreement with recent results for forecasting tools based on foreshocks.

References in corpus (5)

• Scale free networks of earthquakes and aftershocks
• The role of static stress diffusion in the spatio-temporal organization of aftershocks
• Fault heterogeneity and the connection between aftershocks and afterslip
• Aftershock production rate of driven viscoelastic interfaces
• Spatiotemporal correlations of earthquakes in the continuum limit of the one-dimensional Burridge-Knopoff model