Persistence and Quiescence of Seismicity on Fault Systems

TL;DR

This paper investigates the statistical persistence of seismic activity on fault systems using simulations and mean field theory, revealing a new universality class influenced by heterogeneity and fault distance.

Contribution

It introduces a quasistatic fault model and identifies a novel universality class for seismic persistence phenomena based on heterogeneity and fault separation.

Findings

Persistence probability follows a power-law decay with exponent depending on heterogeneity.

Mean field theory successfully explains the dependence of persistence on fault properties.

Results are robust with respect to noise and fault number.

Abstract

We study the statistics of simulated earthquakes in a quasistatic model of two parallel heterogeneous faults within a slowly driven elastic tectonic plate. The probability that one fault remains dormant while the other is active for a time Dt following the previous activity shift is proportional to the inverse of Dt to the power 1+x, a result that is robust in the presence of annealed noise and strength weakening. A mean field theory accounts for the observed dependence of the persistence exponent x as a function of heterogeneity and distance between faults. These results continue to hold if the number of competing faults is increased. This is related to the persistence phenomenon discovered in a large variety of systems, which specifies how long a relaxing dynamical system remains in a neighborhood of its initial configuration. Our persistence exponent is found to vary as a function of heterogeneity and distance between faults, thus defining a novel universality class.