Earthquake-fault dip angle statistics for PSHA analyses

Abstract

The dip angle is one of the fault parameters that mostly affects seismic hazard analyses because it not only influences the inference of other fault parameters (e.g. down-dip width, earthquake maximum magnitude based on fault scaling laws) but also, and most importantly, controls the fault-to-site distance values of ground motion estimates.

We present the results of a global survey of earthquake-fault dip angles (G-DIP) and analyze their empirical distribution for various faulting categories. These new empirical statistics are derived from an extended and homogeneous dataset, thereby improving previous fault dip-angle distributions. Subduction interface sources are considered separately from other thrust faults.

In agreement with other studies, important deviations from the classical Anderson’s predictions are found for all faulting categories (Fig. 1).

Our results can effectively be used as distribution priors for characterizing the geometry of poorly known seismogenic faults in seismic hazard analyses and earthquake-fault modeling experiments.