Sensitivity of the Static Earthquake Triggering Mechanism to Elastic Heterogeneity and Main Event Slip

TL;DR

This study investigates how elastic heterogeneity and fault slip influence static earthquake triggering, using layered Earth models and Green's tensor to analyze stress transfer and inversion of source slip from aftershock data.

Contribution

It introduces a layered Earth Green's tensor approach to assess elastic heterogeneity effects and source slip impact on static stress transfer, with a computational toolkit for arbitrary fault geometries.

Findings

Elastic heterogeneity has a measurable but lower impact on stress transfer.

Fault slip and geometry significantly influence triggered stress.

Maximizing Coulomb stress transfer aids in inverting source slip.

Abstract

This paper has evolved out of our previous work on static stress transfer, where we used the full-space elastostatic Green's tensor to compute the Coulomb stress transfer impact of the Landers earthquake on the Hector Mine event. In this work, we use the elastostatic Green's tensor for an arbitrary layered Earth model with free-surface boundary conditions to study the impact of elastic heterogeneity as well as source-fault slip and geometry on the stress transfer mechanism. Slip distribution and fault geometry of the source have a significant impact on the stress transfer, especially in case of spatially extended triggered events. Maximization of the Coulomb stress transfer function for known aftershocks provides a mechanism for inverting for the source event slip. Heterogeneity of the elastic earth parameters is shown to have a sizeable, but lower-magnitude, impact on the static stress transfer in 3D. The analysis is applied to Landers/Hector Mine and 100 small "aftershocks" of the Landers event. A computational toolkit is provided for the study of static stress transfer for arbitrary source and receiver faults in layered Earth.