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Published May 2022 | Published
Journal Article Open

Subduction earthquake sequences in a non-linear visco-elasto-plastic megathrust


We present a 2-D thermomechanical computational framework for simulating earthquake sequences in a non-linear visco-elasto-plastic compressible medium. The method is developed for a plane-strain problem and incorporates an invariant formulation of the classical rate- and state-dependent friction law and an adaptive time-stepping, which allows the time step to vary by many orders of magnitude during a simulation. Long-term tectonic convergence is imposed by displacing a boundary at a constant rate, whereas temperature-dependent viscosity is solved using a rapidly converging Newton–Raphson scheme. The 2-D volume is discretized using finite differences on a fully staggered grid and marker-in-cell techniques. An adaptive free-surface approximation is used to modulate the air viscosity with the time step, which allows stresses to vanish on the free surface during the propagation of fast slipping events. We present a set of increasingly complex models in which we investigate how inertia, radiation damping, thermally activated non-linear rheology and off-megathrust splay-fault events affect sequences of seismic and aseismic slip on a simplified subduction megathrust. The new method provides a unique computational framework to analyse earthquake sequences and to connect forearc deformation with the dynamic properties of the megathrust, thus providing a physical link between observations spanning from slow interseismic strain accumulation to localized coseismic slip of individual earthquakes and post-seismic viscoelastic relaxation.

Additional Information

© The Author(s) 2021. Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Revision received: 22 August 2021. Received: 10 December 2021. Accepted: 22 December 2021. Published: 27 December 2021. We thank Casper Pranger, Robert Herrendörfer, Camilla Penney, Sylvain Barbot, Valére Lambert and Whitney Behr for discussions. This research was supported by the Swiss National Science Foundation (SNSF) (grants No. P2EZP2_184307 and P400P2_199295), the United States Geological Survey (USGS) Earthquake Hazard Program (grant No. GP21AP10037) and by the Cecil & Sally Drinkward postdoctoral fellowship of the Department of Mechanical and Civil Engineering at the California Institute of Technology. Numerical simulations were performed on ETH cluster Euler. We thank the Editor Margarita Segou, Duo Li and an anonymous reviewers for providing insightful comments that helped to improve the quality of this paper. DATA AVAILABILITY. The data underlying this paper will be shared on reasonable request to the corresponding author. CODE AVAILABILITY. Computer code used within the manuscript is still under development and is available from the corresponding author upon reasonable request.

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Additional details

August 22, 2023
August 22, 2023