Recurrence time distributions of large earthquakes in conceptual model studies

The recurrence time distribution of large earthquakes in seismically active regions is a crucial ingredient for seismic hazard assessment. However, due to sparse observational data and a lack of knowledge on the precise mechanisms controlling seismicity, this distribution is unknown. In many practical applications of seismic hazard assessment, the Brownian passage time (BPT) distribution (or a different distribution) is fitted to a small number of observational recurrence times. Here, we study various aspects of recurrence time distributions in conceptual models of individual faults and fault networks: First, the dependence of the recurrence time distribution on the fault interaction is investigated by means of a network of Brownian relaxation oscillators. Second, the Brownian relaxation oscillator is modified towards a model for large earthquakes, taking into account also the statistics of intermediate events in a more appropriate way. This model simulates seismicity in a fault zone consisting of a major fault and some surrounding smaller faults with Gutenberg-Richter type seismicity. This model can be used for more realistic and robust estimations of the real recurrence time distribution in seismic hazard assessment.