A Divide-and-Conquer Strategy for Fast, Full Elastodynamic Simulation of Earthquakes and Asiesmic Slip on Complex Fault Networks

Federico Ciardo, & Pierre Romanet

Submitted September 7, 2025, SCEC Contribution #14688, 2025 SCEC Annual Meeting Poster #TBD

Understanding how faults accumulate and release stress over time can be accomplished through numerical simulations that accurately resolve both rapid, dynamic ruptures and slow, aseismic slip. These simulations have become indispensable for investigating fault processes that remain hidden from observations—such as how fast and slow slip evolves across geometrically complex, multi-fault systems. However, most existing numerical approaches either approximate elastodynamic (inertial) effects or suffer from prohibitive computational cost.

Here we present a new, computationally efficient approach for simulating Sequences of Earthquakes and Aseismic Slip (SEAS) on geometrically complex fault systems, fully accounting for elastodynamic effects. The proposed framework integrates two formulations of boundary integral equation method: a spectral method to compute fault self-interactions—achieving high accuracy without requiring spatial replication of rupture events—and a classical space-time formulation to resolve fault-to-fault interactions. This marks the first application of a spectral BIE method to SEAS modeling on multiple, arbitrarily oriented planar faults. Another innovation also lies in accelerating and compressing the spatial-temporal convolution of only fault-to-fault interactions using hierarchical matrices. This selective compression enables long-term simulations of SEAS on complex fault networks using standard computing hardware.

The method is developed and verified in the anti-plane shear deformation setting. Benchmark simulations involving interacting faults demonstrate that the hybrid spectral–ℋ-matrix formulation accurately captures both self-induced and inter-fault stress changes. Performance tests reveal substantial gains in computational efficiency: the approach significantly reduces runtime and memory demands, making SEAS simulations more feasible.

Key Words
Dynamic rupture, fault system, simulation

Citation
Ciardo, F., & Romanet, P. (2025, 09). A Divide-and-Conquer Strategy for Fast, Full Elastodynamic Simulation of Earthquakes and Asiesmic Slip on Complex Fault Networks. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)