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Kinematic fault slip evolution source models of the 2008 M7.9 Wenchuan earthquake in China from SAR interferometry, GPS and teleseismic analysis and implications for Longmen Shan tectonics

Fielding, Eric J. and Sladen, Anthony and Li, Zhenhong and Avouac, Jean-Philippe and Bürgmann, Roland and Ryder, Isabelle (2013) Kinematic fault slip evolution source models of the 2008 M7.9 Wenchuan earthquake in China from SAR interferometry, GPS and teleseismic analysis and implications for Longmen Shan tectonics. Geophysical Journal International, 194 (2). pp. 1138-1166. ISSN 0956-540X. http://resolver.caltech.edu/CaltechAUTHORS:20130816-155608675

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Abstract

The M_w 7.9 2008 Wenchuan earthquake ruptured about 280 km of faults in the Longmen Shan of Sichuan province, China, at the eastern edge of the Tibetan Plateau. We use teleseismic waveforms with geodetic data from Global Positioning System, synthetic aperture radar interferometry and image amplitude correlation to produce a source model of this earthquake. The model describes evolution of fault slip during the earthquake. The geodetic data constrains the spatial distribution of fault slip and the seismic waveforms constrain mostly the time evolution of slip. We find that the earthquake started with largely thrust motion on an imbricate system of faults beneath the central Longmen Shan, including the Beichuan Fault and Pengguan Fault, with fault slip at depth extending up to 50 km northwest of the mountain front. The fault ruptures continued northeast along the Beichuan Fault with more oblique slip (right-lateral and thrust) and the proportion of lateral motion increasing in the northern Longmen Shan. The northernmost fault segment has a much steeper dip, consistent with nearly pure strike-slip motion. The kinematic source model shows that the rupture propagated to the northeast at about 2.5–3.0 km s^(−1), producing a cascade of subevents with a total duration of about 110 s. The complex fault ruptures caused shortening and uplift of the extremely steep central Longmen Shan, which supports models where the steep edge of the plateau is formed by thrusting over the strong crust of the Sichuan Basin.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1093/gji/ggt155 DOIArticle
http://gji.oxfordjournals.org/content/194/2/1138PublisherArticle
ORCID:
AuthorORCID
Fielding, Eric J.0000-0002-6648-8067
Avouac, Jean-Philippe0000-0002-3060-8442
Additional Information:© 2013 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. Accepted 2013 April 15. Received 2013 March 1; in original form 2012 June 1. First published online: May 22, 2013. We thank many researchers for sharing their thoughts on this earthquake, including Zheng-Kang Shen, Jing Liu-Zeng, Judith Hubbard, Chen Ji, Dan McKenzie and Ken Hudnut. We thank Kiran Kumar Thingbaijam for help with formatting our slip model results into the SRCMOD format. Envisat data is copyright European Space Agency and provided under projects AOE-668 and Dragon-2 (ID: 5343). ALOS data is copyright Japanese Aerospace Exploration Agency and METI and provided through the US Government Research Consortium Data Pool at the Alaska Satellite Facility and through ALOS PI project 061. Part of this research was supported by the NASA Earth Surface and Interior focus area and performed at the Jet Propulsion Laboratory, California Institute of Technology, Pasadena. Additional support was provided by the National Science Foundation grant EAR-1014880. This research was funded in part by the Gordon and Betty Moore Foundation through Grant GBMF #423.01 to the Caltech Tectonics Observatory. This work was supported in part by the Natural Environmental Research Council through the GAS project (Reference: NE/H001085/1), by the National Centre of Earth Observation of which the Centre for the Observation and Modelling of Earthquakes, Volcanoes, and Tectonics (COMET+) is a part. Caltech Tectonics Observatory Contribution 227.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funders:
Funding AgencyGrant Number
NASAUNSPECIFIED
NSFEAR-1014880
Gordon and Betty Moore FoundationGBMF 423.01
Natural Environmental Research Council (NERC)NE/H001085/1
National Centre of Earth Observation UNSPECIFIED
Subject Keywords:Radar interferometry; Earthquake source observations; Seismicity and tectonics; Body waves; Continental tectonics: compressional
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory227
Record Number:CaltechAUTHORS:20130816-155608675
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130816-155608675
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:40714
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Aug 2013 23:20
Last Modified:20 Oct 2017 23:20

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