Intermittent lab earthquakes in dynamically weakening fault gouge
- Creators
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Rubino, V.
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Lapusta, N.
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Rosakis, A. J.
Abstract
Large and destructive earthquakes on mature faults in Earth's crust occur as slip in a layer of a fine granular material—fault gouge—produced by comminution during sliding. A range of insights into the frictional resistance of faults—one of the main factors controlling earthquake nucleation, dynamic propagation and arrest, and hence the destructive ground shaking of earthquakes—has been obtained in experiments with spatially uniform slip imposed in small samples. However, how various features of gouge friction combine to determine spontaneous progression of earthquakes is difficult to study in the lab owing to substantial challenges with sample sizes and adequate imaging. Here, using lab experiments, we show that spontaneously propagating dynamic ruptures navigate a fault region with fine rock gouge through complex, intermittent slip processes with dramatic friction evolution. These include repeated arrest of rupture propagation caused by friction strengthening at lower slip rates and dynamic earthquake re-nucleation enabled by pronounced rapid friction weakening at higher slip rates consistent with flash heating. The spontaneous repeated weakening and strengthening of friction in fine rock gouge highlights the fundamental dependence of friction on slip rate and associated processes, such as shear heating, localization and delocalization of shear, and dilation and compaction of the shear layer. Our findings expand experimental support of the concept that co-seismic weakening may enable earthquake rupture to break through stable fault regions, with substantial implications for seismic hazard.
Additional Information
© The Author(s), under exclusive licence to Springer Nature Limited 2022. Received 16 April 2021; Accepted 08 April 2022; Published 01 June 2022. This study was supported by the US National Science Foundation (NSF) (EAR-2045285 and EAR-1651235), the US Geological Survey (USGS) (grants G20AP00037 and G16AP00106), the NSF-IUCRC at California Institute of Technology-Center for Geomechanics and Mitigation of Geohazards (GMG), and the Southern California Earthquake Center (SCEC), contribution number 11854. SCEC is funded by NSF Cooperative Agreement EAR-1600087 and USGS Cooperative Agreement G17AC00047. Data availability: The data generated in this study are available through the CaltechDATA repository at https://data.caltech.edu/records/2155. Source data are provided with this paper. Contributions: V.R., AJ.R. and N.L. contributed to developing the main ideas, interpreting the results and producing the manuscript. V.R. performed the measurements and analysed the data. The authors declare no competing interests. Peer review information: Nature thanks Giulio Di Toro and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.Attached Files
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Additional details
- Eprint ID
- 115008
- Resolver ID
- CaltechAUTHORS:20220602-794026200
- NSF
- EAR-2045285
- NSF
- EAR-1651235
- USGS
- G20AP00037
- USGS
- G16AP00106
- Center for Geomechanics and Mitigation of Geohazards
- Southern California Earthquake Center (SCEC)
- NSF
- EAR-1600087
- USGS
- G17AC00047
- Created
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2022-06-02Created 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, GALCIT, Seismological Laboratory
- Other Numbering System Name
- Southern California Earthquake Center
- Other Numbering System Identifier
- 11854