The role of three-dimensional fault interactions in creating complex seismic sequences

Abstract
A physics-based earthquake simulator should reproduce first-order empirical power-law behaviors of magnitudes and clustering. These laws have emerged spontaneously in either discrete or low-dimension continuum simulations without power-law or stochastic heterogeneity. We show that the same emergence can occur in 3-D continuum simulations with fault interactions and rate-and-state friction. Our model approximates a strike-slip fault system as three en echelon faults. Simulations show spatio-temporally clustered earthquake sequences exhibiting characteristic Gutenberg-Richter scaling as well as empirical inter-event time distribution. The Gutenberg-Richter scaling occurs only in partial ruptures that result from fault interactions. With fault interactions, partial ruptures emerge when seismogenic width W over characteristic nucleation length L∞ is larger than 16.24, but none occur without fault interaction. The mainshock recurrence times of individual faults remain quasi-periodic. The system mainshock recurrence time is a combination of short-term Omori-type decay and Brownian passage time. Higher W/L∞ increase short-term clustering probability to at most 30%. These results indicate that physics-based multi-cycle models adequately reflect observed statistical signatures and show practical potential for long-term hazard assessment and medium-term forecasting.

Citation
Yin, Y., Galvez, P., Heimisson, E. R., & Wiemer, S. (2023). The role of three-dimensional fault interactions in creating complex seismic sequences. Earth and Planetary Science Letters, 606, 118056. https://doi.org/10.1016/j.epsl.2023.118056

Acknowledgements
The authors have no conflicts of interest to declare. This research is funded by SED credit number 22818. ERH acknowledges funding from the ETH Zürich Postdoctoral Fellowship (Project No. FEL-19 20-2). YY would like to thank Dr. P. A. Selvadurai and Dr. A. P. Rinaldi for the valuable discussions. The authors thank editor Prof. Rebecca Bendick, reviewer prof. B. A. Erickson, and two anonymous reviewers, who's critical comments substantially improved the manuscript. The simulations are carried out on the ETH Zürich Euler cluster.

Publisher
Elsevier BV

Journal
Earth and Planetary Science Letters

DOI
10.1016/j.epsl.2023.118056

Additional Links
https://linkinghub.elsevier.com/retrieve/pii/S0012821X23000699

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