Modeling earthquakes with off-fault damage using the combined finite-discrete element method

TL;DR

This paper introduces a numerical framework combining finite and discrete element methods to model off-fault damage during earthquakes, capturing complex rupture dynamics and geometrical complexities.

Contribution

It develops a novel FDEM-based simulation approach to accurately model coseismic off-fault fracture networks and their effects on rupture behavior.

Findings

Off-fault damage significantly influences rupture dynamics.

Complex fault geometries affect off-fault fracture patterns.

The model successfully simulates damage in various fault configurations.

Abstract

When a dynamic earthquake rupture propagates on a fault in the Earth's crust, the medium around the fault is dynamically damaged due to stress concentrations around the rupture tip. Recent field observations, laboratory experiments and canonical numerical models show the coseismic off-fault damage is essential to describe the coseismic off-fault deformation, rupture dynamics, radiation and overall energy budget. However, the numerical modeling of "localized" off-fault fractures remains a challenge mainly because of computational limitations and model formulation shortcomings. We thus developed a numerical framework for modeling coseismic off-fault fracture networks using the combined finite-discrete element method (FDEM) and we applied it to simulate dynamic ruptures with coseismic off-fault damage on various fault configurations. This paper addresses the role of coseismic off-fault damage on rupture dynamics associated with a planar fault, as a base case, and with a number of first-order geometrical complexities, such as fault kink, step-over and roughness.