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Dynamic rupture activation of backthrust fault branching

Xu, Shiqing and Fukuyama, Eiichi and Ben-Zion, Yehuda and Ampuero, Jean-Paul (2015) Dynamic rupture activation of backthrust fault branching. Tectonophysics, 644 . pp. 161-183. ISSN 0040-1951. doi:10.1016/j.tecto.2015.01.011.

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We perform dynamic rupture simulations to investigate the possible reactivation of backthrust branches triggered by ruptures along a main thrust fault. Simulations with slip-weakening fault friction and uniform initial stress show that fast propagation speed or long propagation distance of the main rupture promotes reactivation of backthrust over a range of branch angles. The latter condition may occur separately from the former if rupture speed is limited by an increasing slip-weakening distance towards the junction direction. The results suggest a trade-off between the amplitude and duration of the dynamic stress near the main rupture front for backthrust reactivation. Termination of the main rupture by a barrier can provide enhanced loading amplitude and duration along a backthrust rooted near the barrier, facilitating its reactivation especially with a high frictional resistance. The free surface and depth-dependent initial stress can have several additional effects. The sign of the triggered motion along the backthrust can be reversed from thrust to normal if a deeply nucleated main rupture breaks the free surface, while it is preserved as thrust if the main rupture is terminated by a barrier at depth. The numerical results are discussed in relation to several recent megathrust earthquakes in Sumatra, Chile, and Japan, and related topics such as branch feedbacks to the main fault. The dynamic view on backthrust fault branching provided by the study fills a gap not covered by quasi-static models or observations. A specific examined case of antithetic fault branching may be useful for indicating a barrier-like behavior along the main fault.

Item Type:Article
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URLURL TypeDescription
Ben-Zion, Yehuda0000-0002-9602-2014
Ampuero, Jean-Paul0000-0002-4827-7987
Additional Information:© 2015 Elsevier B.V. Received 28 August 2014, Revised 13 January 2015, Accepted 21 January 2015, Available online 3 February 2015. We thank the Editor Jean-Philippe Avouac and two reviewers for constructive comments. We thank Surendra Somala for generating the numerical mesh with software CUBIT. S. Xu also benefits from discussions with Kelin Wang during a meeting, with Yongen Cai during a seminar, and with Wataru Suzuki and Daisuke Inazu on the 2011 Tohoku earthquake. Some numerical simulations were performed at NIED's supercomputer center. This work is supported by the NIED project entitled “Development of the Earthquake Activity Monitoring and Forecasting” and the MEXT project entitled “Wide-area Earthquake Disaster Prevention Research along Nankai Trough”.
Group:Seismological Laboratory
Funding AgencyGrant Number
National Research Institute for Earth Science and Disaster Prevention (NIED)UNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Subject Keywords:Fault branching; Dynamic rupture propagation; Earthquake rupture interaction; Backthrust faulting; Subduction earthquakes
Record Number:CaltechAUTHORS:20150423-105209879
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Official Citation:Shiqing Xu, Eiichi Fukuyama, Yehuda Ben-Zion, Jean-Paul Ampuero, Dynamic rupture activation of backthrust fault branching, Tectonophysics, Volumes 644–645, 16 March 2015, Pages 161-183, ISSN 0040-1951, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56915
Deposited By: Ruth Sustaita
Deposited On:23 Apr 2015 19:22
Last Modified:10 Nov 2021 21:05

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