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Spatially variable fault friction derived from dynamic modeling of aseismic afterslip due to the 2004 Parkfield earthquake

Chang, Shu-Hao and Avouac, Jean-Philippe and Barbot, Sylvain and Lee, Jian-Cheng (2013) Spatially variable fault friction derived from dynamic modeling of aseismic afterslip due to the 2004 Parkfield earthquake. Journal of Geophysical Research. Solid Earth, 118 (7). pp. 3431-3447. ISSN 2169-9313. doi:10.1002/jgrb.50231.

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We investigate fault friction from dynamic modeling of fault slip prior to and following the M_w 6.0 earthquake which ruptured the Parkfield segment of the San Andreas Fault in 2004. The dynamic modeling assumes a purely rate-strengthening friction law, with a logarithmic dependency on sliding rate: μ= μ*+(a-b)ln(v/v*). The initial state of stress is explicitly taken into account, and afterslip is triggered by the stress change induced by the earthquake source model given a priori. We consider different initial stress states and two coseismic models, and invert for the other model parameters using a nonlinear inversion scheme. The model parameters include the reference friction μ*, the friction rate dependency characterized by the quantity a-b, assumed to be either uniform or depth dependent. The model parameters are determined from fitting the transient postseismic geodetic signal measured at continuous GPS stations. Our study provides a view of frictional properties at the kilometers scale over the 0–15 km depth illuminated by the coseismic stress change induced by the Parkfield earthquake. The reference friction is estimated to be between 0.1 and 0.5. With independent a priori constraints on the amplitude of differential stress, the range of possible values narrows down to 0.1–0.17. The friction rate coefficient a-b is estimated to be ∼ 10^(− 3) − 10^(− 2) with a hint that it increases upward from about 1–3 × 10^(–3) at 3–7 km depth to about 4–7 × 10^(–3) at 0–1 km depth. It is remarkable that our results are consistent with frictional properties measured on rock samples recovered from the fault zone thanks to the San Andreas Fault Observatory at Depth experiment.

Item Type:Article
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URLURL TypeDescription DOIArticle
Avouac, Jean-Philippe0000-0002-3060-8442
Barbot, Sylvain0000-0003-4257-7409
Additional Information:© 2013 American Geophysical Union. Received 14 September 2012; revised 22 May 2013; accepted 29 May 2013; published 2 July 2013. The National Science Council of Taiwan is thanked for supporting S.-H. Chang’s postdoctoral fellowship at the California Institute of Technology. The grants are NSC 99-2911-I- 001-009 and NSC 100-2911-I-001-006. Brett Carpenter and André Niemeijer are thanked for providing thorough and detailed reviews which helped clarify the text and figures. This study was funded by the Gordon and Betty Moore Foundation through Grant GBMF #423.01 to the Caltech Tectonics Observatory. This is Tectonics Observatory publication #229. This study was supported partially by NSC 101-2116-M-001-005 and the publication # is IESAS1819.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funding AgencyGrant Number
National Science Council (Taipei)99-2911-I-001-009
National Science Council (Taipei)100-2911-I-001-006
Gordon and Betty Moore FoundationGBMF 423.01
National Science Council (Taipei)101-2116-M-001-005
Subject Keywords:fault friction; afterslip; rate-strengthening; Parkfield
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Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory229
Issue or Number:7
Record Number:CaltechAUTHORS:20131104-094125115
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Official Citation:Chang, S.-H., J.-P.Avouac, S.Barbot, and J.-C.Lee (2013), Spatially variable fault friction derived from dynamicmodeling of aseismic afterslip due to the 2004 Parkfield earthquake, J. Geophys. Res. Solid Earth, 118, 3431–3447, doi:10.1002/jgrb.50231
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42215
Deposited By: Tony Diaz
Deposited On:04 Nov 2013 18:34
Last Modified:10 Nov 2021 16:20

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