Size-frequency relation of earthquakes in load-transfer models of fracture

Abstract

Using Monte Carlo simulations of the process of breaking in arrays of elements with load-transfer rules, we have obtained the size- frequency relation of the avalanches occurring in 1- and 2-dimensional stochastic fracture models. The resulting power-law behaviour resembles the Gutenberg-Richter law for the relation between the size (liberated energy) of earthquakes and their number frequency. The value of the power law exponent is calculated as a function of the degree of stress dissipation present in the model. The degree of dissipation is implemented in a straightforward and simple way by assuming that only a fraction of the stress is transferred in each breaking event. The models are robust with respect to the degree of dissipation and we observe a consistent power-law behaviour for a broad range of dissipation values, both in ID and 2D. The value of the power-law exponent is similar to the phenomenological b- value (0.8 b 1.1) for intermediate magnitude earthquakes.