Persistence and quiescence of seismicity on fault systems

We study the statistics of simulated earthquakes in a quasistatic model of two parallel heterogeneous faults within a slowly driven elastic tectonic p late. The probability that one fault remains dormant while the other is act ive for a time Delta t following the previous activity shift is proportiona l to Delta t(-(1+x)), a result that is robust in the presence of annealed n oise 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 c ompeting faults is increased.