Temporal and Magnitude Dependence in Earthquake Recurrence Models

The effects of temporal and magnitude dependence among seismic recurrences, which are ignored in the conventional Poisson earthquake model, are studied. The potential impact of non-Poissonian assumptions on practical hazard estimates are considered. A broad set of recurrence models with memory are analyzed using convenient second-moment time-magnitude statistics to parameterize a general class of semi-Markov models. The conventional time- and slip-predictable models are included and studied as special cases. Conditions are identified under which the Poisson model provides a sufficient engineering hazard estimate. i.e., either conservative or unconservative by a factor of no more than three. The Poisson approximation is found to be sufficient for all but what is expected to be a small subset of the cases encountered in practice.