Frictional Properties of Simulated Fault Gouges Subject to Normal Stress Oscillation and Implications for Induced Seismicity

Bowen Yu, Jianye Chen*, Christopher J. Spiers, Shengli Ma, Miao Zhang, Wenbo Qi, Hao Chen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Under critical conditions where experimental fault slip exhibits self-sustained oscillation, effects of normal stress oscillation (NSO) on fault strength and stability remain poorly understood, as do potential effects of NSO on natural and induced seismicity. In this study, we employed double direct-shear testing to investigate the frictional behavior of a synthetic, slightly velocity-weakening (SVW) fault gouge (characterized by self-sustained oscillation under quasi-static shear loading), when subjected to NSO at different amplitudes (5%–20% of 5 MPa) and frequencies (0.001–1 Hz). During the experiment, fault displacement and gouge layer thickness were measured. Transmitted ultrasonic waves were also employed to probe grain contact states within the gouge layer. Our results show that fault weakening and unstable slip can be triggered at NSO frequencies ranging from 0.03 to 0.1 Hz and amplitudes exceeding 5%. Interestingly, an amplified shear stress drop and weakening effect were observed when the NSO frequency fell in 0.05–0.1 Hz. Analysis of transmitted ultrasonic waves in tests on the SVW gouge revealed fault dilation, accompanied by unstable slip and weakening. By extending an existing microphysical model (the “Chen-Niemeijer-Spiers [CNS]” model), to account for elastic effects of NSO on gouge microstructure and grain contact state, the mechanical and wave data obtained in our experiments on the SVW gouge was reproduced, suggesting an approach for modeling fault instability under upper crustal (SVW) conditions where normal stress is perturbed by subsurface operations, such as periodic gas storage stimulation of reservoir formations.

Original languageEnglish
Article numbere2024JB029521
JournalJournal of Geophysical Research: Solid Earth
Volume129
Issue number9
DOIs
Publication statusPublished - 1 Sept 2024

Bibliographical note

Publisher Copyright:
© 2024. American Geophysical Union. All Rights Reserved.

Funding

This study was supported by the National Natural Science Foundation of China (Grants U1839211 and U2239204 to Shengli Ma, Grant 42174224 to Jianye Chen). The work was also supported in part by the DeepNL research programme (Science4Steer Project, project number DEEP.NL.2018.046), financed by the Dutch Research Council (NWO). B. Yu acknowledges the China Scholarship Council for providing funding to perform the theoretical part of this study at Utrecht University. We thank Yanshuang Guo, Jiahui Feng and Qingbao Duan for the technique help in running the friction experiments and the compaction test. We thank the editor Prof. Alexandre Schubnel, an anonymous associated editor, an anonymous reviewer, and Prof. John W. Rudnicki for the constructive suggestions on this work.

FundersFunder number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Universiteit Utrecht
China Scholarship Council
National Natural Science Foundation of China42174224, U2239204, U1839211
DeepNLDEEP.NL.2018.046

    Keywords

    • fault friction
    • induced seismicity
    • microphysical model
    • normal stress oscillation
    • slightly velocity-weakening gouge

    Fingerprint

    Dive into the research topics of 'Frictional Properties of Simulated Fault Gouges Subject to Normal Stress Oscillation and Implications for Induced Seismicity'. Together they form a unique fingerprint.

    Cite this