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Nearly magnitude‐invariant stress drops in simulated crack‐like earthquake sequences on rate‐and‐state faults with thermal pressurization of pore fluids

Perry, Stephen M. and Lambert, Valère and Lapusta, Nadia (2020) Nearly magnitude‐invariant stress drops in simulated crack‐like earthquake sequences on rate‐and‐state faults with thermal pressurization of pore fluids. Journal of Geophysical Research. Solid Earth, 125 (3). Art. No. e2019JB018597. ISSN 2169-9313. https://resolver.caltech.edu/CaltechAUTHORS:20200306-132842975

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Abstract

Stress drops, inferred to be magnitude‐invariant, are a key characteristic used to describe natural earthquakes. Theoretical studies and laboratory experiments indicate that enhanced dynamic weakening, such as thermal pressurization of pore fluids, may be present on natural faults. At first glance, magnitude invariance of stress drops and enhanced dynamic weakening seem incompatible since larger events may experience greater weakening and should thus have lower final stresses and higher stress drops. We hypothesize that enhanced dynamic weakening can be reconciled with magnitude‐invariant stress drops due to larger events having lower average prestress when compared to smaller events. We conduct numerical simulations of long‐term earthquake sequences in fault models with rate‐and‐state friction and thermal pressurization, and in the parameter regime that results mostly in crack‐like ruptures, we find that such models can explain both the observationally inferred stress drop invariance and increasing breakdown energy with event magnitude. Smaller events indeed have larger average initial stresses than medium‐sized events, and we find nearly constant stress drops for events spanning up to two orders of magnitude in average slip, comparable to approximately six orders of magnitude in seismic moment. Segment‐spanning events have more complex behavior, which depends on the properties of the arresting velocity‐strengthening region at the edges of the faults.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2019jb018597DOIArticle
https://data.caltech.edu/records/1377DOIData
ORCID:
AuthorORCID
Lambert, Valère0000-0002-6174-9651
Lapusta, Nadia0000-0001-6558-0323
Additional Information:© 2020 American Geophysical Union. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Issue Online: 14 March 2020; Version of Record online: 14 March 2020; Accepted manuscript online: 04 March 2020; Manuscript accepted: 28 February 2020; Manuscript revised: 18 January 2020; Manuscript received: 03 September 2019. This study was supported by the National Science Foundation (Grants EAR 1142183 and 1520907) and the Southern California Earthquake Center (SCEC), Contribution No. 8128. SCEC is funded by NSF Cooperative Agreement EAR‐1033462 and USGS Cooperative Agreement G12AC20038. The numerical simulations for this work were done on the supercomputing cluster in the Caltech Division for Geology and Planetary Science. The data supporting the analysis and conclusions is given in Figures and Tables. Data is accessible through the CaltechDATA repository (https://data.caltech.edu/records/1377). We thank Jean‐Philippe Avouac, Victor Tsai, and Zhongwen Zhan for helpful discussions, Semechah Lui and Natalie Higgins for help with the simulation code, and Alice‐Agnes Gabriel and an anonymous reviewer for thoughtful reviews that helped us improve the manuscript.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR 1142183
NSFEAR-1520907
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-1033462
USGSG12AC20038
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center8128
Issue or Number:3
Record Number:CaltechAUTHORS:20200306-132842975
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200306-132842975
Official Citation:Perry, S. M., Lambert, V., & Lapusta, N. (2020). Nearly magnitude‐invariant stress drops in simulated crack‐like earthquake sequences on rate‐and‐state faults with thermal pressurization of pore fluids. Journal of Geophysical Research: Solid Earth, 125, e2019JB018597. https://doi.org/10.1029/2019JB018597
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101744
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:06 Mar 2020 21:43
Last Modified:17 Mar 2020 19:35

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