Time-Dependent Earthquake Probability Computations and Fault Interaction Effects in Zagros, Iran

When a relatively strong earthquake occurs, it changes the conditions for failure in its proximity and alters the occurrence probability for future events. In this study, the occurrence probability of future earthquakes with magnitudes Mw≥5.8 on the basis of Brownian passage-time (BPT) and Weibull Time-dependent models is calculated for the next 10, 30 and 50 years in the Zagros region. According to the method used in recent years, initially, the Coulomb stress changes caused by earthquakes interaction is computed on each fault. Then, the impact of this stress change on the occurrence probability of next characteristic earthquakes is calculated, taking into account both permanent (clock advance) and transient (rate-and-state) effects of stress changes. We concentrated on the long term slip rate uncertainties by generating 1000 random numbers using the Monte Carlo technique. We find that earthquake interaction effects in this region are small. Thus, permanent and transient effects of stress change do not affect the calculated probabilities very much. The maximum probability is related to the Kazerun fault that shows the high seismic activity of this fault.