Propagation of large earthquakes as self-healing pulses or mild cracks
- Creators
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Lambert, Valère
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Lapusta, Nadia
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Perry, Stephen
Abstract
Observations suggest that mature faults host large earthquakes at much lower levels of stress than their expected static strength. Potential explanations are that the faults are quasi-statically strong but experience considerable weakening during earthquakes, or that the faults are persistently weak, for example, because of fluid overpressure. Here we use numerical modelling to examine these competing theories for simulated earthquake ruptures that satisfy the well known observations of 1–10 megapascal stress drops and limited heat production. In that regime, quasi-statically strong but dynamically weak faults mainly host relatively sharp, self-healing pulse-like ruptures, with only a small portion of the fault slipping at a given time, whereas persistently weak faults host milder ruptures with more spread-out slip, which are called crack-like ruptures. We find that the sharper self-healing pulses, which exhibit larger dynamic stress changes compared to their static stress changes, result in much larger radiated energy than that inferred teleseismically for megathrust events. By contrast, milder crack-like ruptures on persistently weak faults, which produce comparable static and dynamic stress changes, are consistent with the seismological observations. The larger radiated energy of self-healing pulses is similar to the limited regional inferences available for crustal strike-slip faults. Our findings suggest that either large earthquakes rarely propagate as self-healing pulses, with potential differences between tectonic settings, or their radiated energy is substantially underestimated, raising questions about earthquake physics and the expected shaking from large earthquakes.
Additional Information
© 2021 Nature Publishing Group. Received 08 November 2019; Accepted 18 January 2021; Published 10 March 2021. This study was supported by the US National Science Foundation (NSF) (grants EAR 1142183 and 1520907), the US Geological Survey (grant G19AP00059) and the Southern California Earthquake Center (SCEC), contribution no. 10085. SCEC is funded by NSF Cooperative Agreement EAR 1033462 and US Geological Survey Cooperative Agreement G12AC20038. Numerical simulations for this study were carried out on the High Performance Computing Center cluster of the California Institute of Technology. We thank H. Kanamori, T. Heaton, J.-P. Avouac, V. Tsai and Z. Zhan for discussions and comments. Data availability: Numerical data are accessible through the CaltechDATA repository (https://data.caltech.edu/records/1620). Seismological inferences used in this study are compiled from published literature and publicly available sources. Source data are provided with this paper. Code availability: The numerical methodology used in this study is described in the Supplementary Materials and references32,49. Author Contributions: V.L and N.L contributed to developing the main ideas, interpreting the results and producing the manuscript. S.P. performed preliminary simulations comparing crack-like ruptures and self-healing pulses. V.L. designed, carried out and analysed the numerical experiments described in the paper. The authors declare no competing interests. Peer review information: Nature thanks Jeffrey J. McGuire, Peter Shearer and Alice-Agnes Gabriel for their contribution to the peer review of this work.Attached Files
Supplemental Material - 41586_2021_3248_MOESM1_ESM.pdf
Supplemental Material - 41586_2021_3248_MOESM2_ESM.mp4
Supplemental Material - 41586_2021_3248_MOESM3_ESM.mp4
Supplemental Material - 41586_2021_3248_MOESM4_ESM.mp4
Supplemental Material - 41586_2021_3248_MOESM5_ESM.xlsx
Supplemental Material - 41586_2021_3248_MOESM6_ESM.xlsx
Supplemental Material - 41586_2021_3248_MOESM7_ESM.xlsx
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Additional details
- Eprint ID
- 108386
- Resolver ID
- CaltechAUTHORS:20210310-112130851
- NSF
- EAR-1142183
- NSF
- EAR-1520907
- USGS
- G19AP00059
- Southern California Earthquake Center (SCEC)
- NSF
- EAR-1033462
- USGS
- G12AC20038
- Created
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2021-03-10Created 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
- Other Numbering System Name
- Southern California Earthquake Center
- Other Numbering System Identifier
- 10085