Modeling frictional precursory phenomena using a wear-based rate- and state-dependent friction model in the laboratory

Abstract
We examine numerical models that employ the rate-and-state frictional (RSF) framework to investigate earthquake sequences using laboratory driven descriptions of heterogeneous frictional properties. Using previously obtained experimental measurement of roughness, we observed that wear produced a bimodal Gaussian distribution of surface heights, which we hypothesized produced spatial heterogeneity of the critical slip distance Dc. In this numerical study, the fault surface was binarized into discrete smooth or rough sections, producing a barcode style version of frictional heterogeneity. The fault was predominantly rough except for two dominant asperities (A1 and A2) representative of larger polished sections. We simulated the resistive effect of increasing the fracture energy (toughness) of the rough barriers while maintaining constant properties of the embedded brittle/smooth asperities. Our numerical simulations generated burst-like seismic events and aseismic transients throughout the interseismic phase. At the late interseismic phase, bursts of seismicity (foreshocks) interacted with the accelerating preslip region at the transition to the preseismic (nucleation) phase. At lower levels of toughness heterogeneity, the slip rate increase was roughly inversely proportional to the time-to-failure tf for larger events. As fault toughness was increased, the dominant asperities initiated nucleation and thus force deviations of the fault from the smooth 1/tf acceleration observed for the homogeneous case, producing a rate-dependent cascade response. The calculations were validated by comparing two independently measured metrics from the experiments: (1) The expansion rate of slow ruptures during the interseismic and preslip phase and (2) the scalar seismic moment and source dimensions. While our study does not address the scaling problem, these results help to understand laboratory experiments that investigate transition to the preseismic (nucleation) phase during complex earthquake sequences.

Citation
Selvadurai, P. A., Galvez, P., Mai, P. M., & Glaser, S. D. (2023). Modeling frictional precursory phenomena using a wear-based rate- and state-dependent friction model in the laboratory. Tectonophysics, 847, 229689. https://doi.org/10.1016/j.tecto.2022.229689

Acknowledgements
We would like to thank T. Yamaguchi who provided important discussion points regarding the analysis, three anonymous reviewers and thoughtful comments from P. Romanet. Key insights into simulations presented here are given by J.-P. Ampuero. This research was supported by: JSPS KAKENHI Grant No. JP16H06478 in Scientific Research on Innovative Areas “Science of Slow Earthquakes”. Computational resources were provided by the Information Technology Division and Extreme Computing Research Center (ECRC) at KAUST. Funding for parts of this research was provided by the National Science Foundation Grant CMMI-1131582 awarded to SDG at the University of California, Berkeley. Partial funding for PAS was provided from the European Research Council (ERC) project FEAR (grant 856559) under the European Community’s Horizon 2020 Framework Programme. PMM’s contribution to this study and a research visit of PAS to KAUST was supported by KAUST research grant BAS/1/1339–01-01. The authors assume full responsibility for the comments and concepts presented in the paper.

Publisher
Elsevier BV

Journal
TECTONOPHYSICS

DOI
10.1016/j.tecto.2022.229689

Additional Links
https://linkinghub.elsevier.com/retrieve/pii/S0040195122004838

Permanent link to this record