Earthquake Source Parameters Relationships from 3D Rough Fault Dynamic Rupture

Abstract:

Fault surface roughness has a strong influence on the distribution of stress around the fault, and affects the dynamics of the earthquake process. In particular, roughness influences the distribution of the parameters conventionally used to describe fault slip in, for example, kinematic modeling of strong ground motion. We explore the effect of the fault roughness on earthquake source parameters through the statistical analysis of a large suite of 3D rupture simulations. We have built a database of more than 1000 simulated dynamic ruptures based on different rough fault profiles and relative-strength (S) ratios, and have quantitatively analyzed the correlation between earthquake source parameter pairs.. In the subshear propagation-speed regime, we find the following relationships: (1) Rise time, total slip and peak slip rate each decrease with increasing roughness. (2) Rupture velocity is weakly positively related to slip, and the relationship is stronger with increasing roughness. We also explore how peak slip rate, rise time and different pairs of source parameters correlations are affected by fault roughness. This work may give useful guidance for use in kinematic rupture-source generators and help improve methods for ground strong motion prediction.