Estimation methods for occurrence probability of large earth-quakes in the Haiyuan fault zone in northwestern China

In recent 20 years， some researchers have revealed a lot of paleoearthquake events in the Haiyuan fault zone. All available information allows more reliable analysis of the occurrence patterns of large earthquakes occurring in the Haiyuan fault zone. Based on this paleo-seismological information， three fault rupture sources can be inferred， the middle segment and the western segment are secondary rupture sources which are controlled by the full segment. A stochastic characteristic-slip model is presented to calculate the occurrence probability of large earthquakes in the Haiyuan fault zone， assuming the magnitude distribution of different rupture sources all fit the characteristic earthquake model and the average seismic moment accumulation rate of each rupture source is a constant. In addition， preferred annual mean seismic moment accumulation rates can be inferred by using the Monte Carlo method. The result shows that the occurrence probability of large earthquakes (M_W≥6.8) is about 0.0586 in the next 100 years along the Haiyuan fault zone.