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Initiation and Arrest of Earthquake Ruptures due to Elongated Overstressed Regions

Galis, Martin and Ampuero, Jean-Paul and Mai, P. Martin and Kristek, Jozef (2018) Initiation and Arrest of Earthquake Ruptures due to Elongated Overstressed Regions. . (Submitted) http://resolver.caltech.edu/CaltechAUTHORS:20181102-083459055

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Abstract

The initiation of natural and induced earthquakes is promoted in fault areas where the shear stress is close to fault strength. In many important situations, these overstressed fault areas (or “asperities”) are very elongated; for example, in the case of a fault intersecting a reservoir subject to fluid-injection, or the stress concentration along the bottom of a seismogenic zone induced by deep fault creep. Theoretical estimates of the minimum overstressed asperity size leading to runaway rupture and of the final size of self-arrested ruptures are only available for 2D problems and for 3D problems with an asperity aspect ratio close to one. In this study, we determine how the nucleation of ruptures on elongated asperities, and their ensuing arrest, depend on the size and aspect ratio of the asperity and on the background stress. Based on a systematic set of 3D dynamic rupture simulations assuming linear slip-weakening friction, we find that if the shortest asperity side is smaller than the 2D critical length, the problem effectively reduces to a 2D problem in which rupture nucleation and arrest are controlled by the shortest length of the asperity. Otherwise, nucleation and rupture arrest are controlled by the asperity area, with a minor exception: for asperities with shortest side slightly larger than the 2D critical length, arrested ruptures are smaller than predicted by the asperity area. The fact that rupture arrest is dominantly controlled by area, even for elongated asperities, corroborates the finding that observed maximum magnitudes of earthquakes induced by fluid injection are consistent with the theoretical relation between the magnitude of the largest self-arrested rupture and the injected volume (Galis et al., 2017). In context of induced seismicity, our simulations provide plausible scenarios that could be either favourable or challenging for traffic light systems, and provide mechanical insights into the conditions leading to these situations.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
https://doi.org/10.31223/osf.io/dbuk4DOIDiscussion Paper
ORCID:
AuthorORCID
Ampuero, Jean-Paul0000-0002-4827-7987
Additional Information:Academic Free License (AFL) 3.0. This is a non-peer reviewed preprint submitted to EarthArXiv. It has been submitted on Oct-8, 2018 to Geophysical Journal International. The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST), grant BAS/1/1339-01-01. M.G. and J.K. acknowledge partial support by the Slovak Foundation Grant VEGA-2/0188/15. J. P. A. acknowledges partial funding from NAM (Nederlandse Aardolie Maatschappij) and from the French government through the UCA-JEDI Investments in the Future project managed by the National Research Agency (ANR) with the reference number ANR-15-IDEX-01.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
King Abdullah University of Science and Technology (KAUST)BAS/1/1339-01-01
Slovak FoundationVEGA-2/0188/15
Nederlandse Aardolie MaatschappijUNSPECIFIED
Agence Nationale pour la Recherche (ANR)ANR-15-IDEX-01
Subject Keywords:Numerical modelling, Earthquake dynamics, Induced seismicity
Record Number:CaltechAUTHORS:20181102-083459055
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20181102-083459055
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90603
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Nov 2018 16:34
Last Modified:02 Nov 2018 16:34

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