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Response of rate-and-state seismogenic faults to harmonic shear-stress perturbations

Ader, Thomas J. and Lapusta, Nadia and Avouac, Jean-Philippe and Ampuero, Jean-Paul (2014) Response of rate-and-state seismogenic faults to harmonic shear-stress perturbations. Geophysical Journal International, 198 (1). pp. 385-413. ISSN 0956-540X. doi:10.1093/gji/ggu144.

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Field and laboratory observations show that seismicity has non-trivial period-dependent response to periodic stress perturbations. In Nepal, seismicity shows significant variations in response to annual monsoon-induced stress variations but not to semidiurnal tidal stresses of the same magnitude. Such period dependence cannot be explained by the Coulomb failure model and spring-slider rate-and-state model (SRM). Here, we study seismicity response to periodic stress perturbations in a 2-D continuum model of a rate-and-state fault (that is, a finite rate-and-state fault). We find that the resulting seismicity indeed exhibits nearly periodic variations. Their amplitude is maximum at a certain period, T_a, and decreases with smaller and larger periods to the SRM predictions, remaining much larger than the SRM predictions for a wide range of periods around T_a. We attribute the higher sensitivity of finite faults to their finite nucleation zones which vary in space and have a different slip-velocity evolution than that of the SRM. At periods T ≫ T_a and T ≪ T_a, the seismicity-rate variations are in phase with the stress-rate and stress variations, respectively, consistent with the SRM, although a gradual phase shift appears as T increases towards T_a. Based on the similarities with the SRM and our simulations, we propose a semi-analytical expression for T_a. Plausible sets of model parameters make T_a equal to 1 yr, potentially explaining Nepal observations and constraining the fault properties. Our finite-fault findings indicate that aσ, where a is a rate-and-state parameter and σ is the effective normal stress, can be severely underestimated based on the SRM.

Item Type:Article
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URLURL TypeDescription Information
Lapusta, Nadia0000-0001-6558-0323
Avouac, Jean-Philippe0000-0002-3060-8442
Ampuero, Jean-Paul0000-0002-4827-7987
Additional Information:© The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society. Accepted 2014 April 14. Received 2014 April 10; in original form 2013 September 20. This project was supported by the Gordon and Betty Moore Foundation, through the Tectonics Observatory, NSF grant EAR #0838495. This is Caltech Tectonic Observatory’s contribution number 231 and Caltech Seismolab contribution number 10093.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Caltech Tectonics ObservatoryUNSPECIFIED
NSFEAR 0838495
Subject Keywords:Seismic cycle; Earthquake dynamics; Seismicity and tectonics
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory231
Caltech Division of Geological and Planetary Sciences10093
Issue or Number:1
Record Number:CaltechAUTHORS:20140828-112246557
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Official Citation:Ader, T. J., Lapusta, N., Avouac, J.-P., & Ampuero, J.-P. (2014). Response of rate-and-state seismogenic faults to harmonic shear-stress perturbations. Geophysical Journal International, 198(1), 385-413. doi: 10.1093/gji/ggu144
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49020
Deposited On:28 Aug 2014 19:24
Last Modified:10 Nov 2021 18:39

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