Simultaneous Dependence of the Earthquake‐Size Distribution on Faulting Style and Depth

We analyze two high‐quality Southern Californian earthquake catalogues, one with focal mechanisms, to statistically model and test for dependencies of the earthquake‐size distribution, the bvalues, on both faulting style and depth. In our null hypothesis, bis assumed constant. We then develop and calibrate one model based only on faulting style, another based only on depth dependence and two models that assume a simultaneous dependence on both parameters. We develop a new maximum‐likelihood estimator corrected for the degrees of freedom to assess models' performances. Our results show that all models significantly reject the null hypothesis. The best performing is the one that simultaneously takes account of depth and faulting style. Our results suggest that differential stress variations in the Earth's crust systematically influence bvalues and that this variability should be considered for contemporary seismic hazard studies. We model the dependence of the bvalue on depth and tectonic style in Southern CaliforniaStatistical tests reveal that faulting style affects the bvalue more than depthSimultaneous dependencies result with high statistical significance in the best data description