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Published December 21, 2021 | Supplemental Material + Published
Journal Article Open

Dynamic rupture initiation and propagation in a fluid-injection laboratory setup with diagnostics across multiple temporal scales

Abstract

Fluids are known to trigger a broad range of slip events, from slow, creeping transients to dynamic earthquake ruptures. Yet, the detailed mechanics underlying these processes and the conditions leading to different rupture behaviors are not well understood. Here, we use a laboratory earthquake setup, capable of injecting pressurized fluids, to compare the rupture behavior for different rates of fluid injection, slow (megapascals per hour) versus fast (megapascals per second). We find that for the fast injection rates, dynamic ruptures are triggered at lower pressure levels and over spatial scales much smaller than the quasistatic theoretical estimates of nucleation sizes, suggesting that such fast injection rates constitute dynamic loading. In contrast, the relatively slow injection rates result in gradual nucleation processes, with the fluid spreading along the interface and causing stress changes consistent with gradually accelerating slow slip. The resulting dynamic ruptures propagating over wetted interfaces exhibit dynamic stress drops almost twice as large as those over the dry interfaces. These results suggest the need to take into account the rate of the pore-pressure increase when considering nucleation processes and motivate further investigation on how friction properties depend on the presence of fluids.

Additional Information

© 2021 National Academy of Sciences. Published under the PNAS license. Edited by Paul Segall, Department of Geophysics, Stanford University, Stanford, CA; received November 20, 2020; accepted November 3, 2021. This study was supported by the US National Science Foundation (NSF) Grants (EAR-2045285 and EAR-1651235); US Geological Survey Grant G20AP00037; the California Institute of Technology (Caltech) Mechanical and Civil Engineering Big Idea Fund (2019); the Caltech Terrestrial Hazard Observatory and Reporting Center; and the NSF Industry-University Cooperative Research Center for Geomechanics and Mitigation of Geohazards. Data Availability: Structure data have been deposited in CaltechDATA (DOI: https://doi.org/10.22002/D1.1667). Author contributions: M.G., V.R., A.J.R., and N.L. designed research; M.G. performed research; M.G. analyzed data; and M.G., V.R., and N.L. wrote the paper. The authors declare no competing interest. This article is a PNAS Direct Submission. This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2023433118/-/DCSupplemental.

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Published - e2023433118.full.pdf

Supplemental Material - pnas.2023433118.sapp.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023