Impact of Variable Fault Geometries and Slip Rates on Earthquake Catalogs From Physics-Based Simulations of a Normal Fault

Abstract

Earthquake simulators are used to study and anticipate earthquakes. These simulators produce millions of synthetic earthquakes over thousands to millions of years using predefined fault properties. We use a well-defined active normal fault in offshore Aotearoa New Zealand, to examine the impact of nonuniformly distributed fault slip rates and nonplanar fault geometries on the resulting synthetic earthquake catalogs. We show that adopting variable fault slip rates, with a gradual decrease in slip rate toward fault-surface edges, reduces the unrealistic occurrence of high concentrations of earthquakes along the fault tip line. The study also shows that utilization of complex 3D fault geometries together with variable slip rates produces populations of earthquakes in a less predictable manner, increasing the number of moderate to large magnitude events. Therefore, details of the input fault geometries and slip rate distributions can significantly affect the resulting synthetic earthquake catalogs from physics-based earthquake simulators with significant implications for seismic hazard applications.