Fault rock heterogeneity can produce fault weakness and reduce fault stability
Abstract
Geological heterogeneity is abundant in crustal fault zones; however, its role in controlling the mechanical behaviour of faults is poorly constrained. Here, we present laboratory friction experiments on laterally heterogeneous faults, with patches of strong, rate-weakening quartz gouge and weak, rate-strengthening clay gouge. The experiments show that the heterogeneity leads to a significant reduction in strength and frictional stability in comparison to compositionally identical faults with homogeneously mixed gouges. We identify a combination of weakening effects, including smearing of the weak clay; differential compaction of the two gouges redistributing normal stress; and shear localization producing stress concentrations in the strong quartz patches. The results demonstrate that geological heterogeneity and its evolution can have pronounced effects on fault strength and stability and, by extension, on the occurrence of slow-slip transients versus earthquake ruptures and the characteristics of the resulting events, and should be further studied in lab experiments and earthquake source modelling.
Additional Information
© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received 09 June 2021; Accepted 15 December 2021; Published 17 January 2022. Gary Coughlan is thanked for assistance in developing and maintaining the experimental apparatus. We are grateful to Elisabetta Mariani for help with and maintenance of the SEM facilities. This work is supported by Natural Environment Research Council grant NE/P002943/1. Data availability: The associated experimental data files for this research can be accessed in National Geoscience Data Center (NGDC) via the following link: https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item164865. Author Contributions: J.D.B., D.R.F. and N.L. developed the main ideas. J.D.B. performed the experiments, ran microstructural analyses and produced the initial manuscript. All authors contributed to interpreting the results and editing the manuscript. The authors declare no competing interests. Peer review information: Nature Communications thanks Chris Marone, Giulio Di Toro and Terry Tullis for their contribution to the peer review of this work. Peer reviewer reports are available.Attached Files
Published - s41467-022-27998-2.pdf
Submitted - heterogeneous-faults-manuscript_preprint_v3.pdf
Supplemental Material - 41467_2022_27998_MOESM1_ESM.pdf
Supplemental Material - 41467_2022_27998_MOESM2_ESM.pdf
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Additional details
- Eprint ID
- 113126
- Resolver ID
- CaltechAUTHORS:20220127-621076900
- NE/P002943/1
- Natural Environment Research Council (NERC)
- Created
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2022-01-28Created from EPrint's datestamp field
- Updated
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2022-11-15Created from EPrint's last_modified field
- Caltech groups
- Center for Geomechanics and Mitigation of Geohazards (GMG), Division of Geological and Planetary Sciences, Seismological Laboratory