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Lithospheric convective instability could induce creep along part of the San Andreas fault

Le Pourhiet, Laetitia and Saleeby, Jason (2013) Lithospheric convective instability could induce creep along part of the San Andreas fault. Geology, 41 (9). pp. 999-1002. ISSN 0091-7613. http://resolver.caltech.edu/CaltechAUTHORS:20130919-141723383

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Abstract

Along the western border of the Sierra Nevada microplate, the San Andreas fault (California, United States) is comprised of three segments. Two (north and south segments) are locked and support large earthquakes (e.g., the M 7.7 1906 San Francisco and the M 7.8 1857 Fort Tejon earthquakes), while the central segment, from Parkfield to San Juan Bautista, is creeping. Based on mechanical models, we show that the late Pliocene–Quaternary convective removal (delamination) of the southern Sierra Nevada mantle lithosphere and associated uplift of the Sierra Nevada Mountains causes the Great Valley upper crust to deform by flexure and buckling. Additional three-dimensional flexural models imply that the local flexural bulge overlaps with the creeping segment of the fault system, while geological observations indicate that the local weakening of the San Andreas fault started at the same time that the Sierra Nevada started its recent phase of uplift. We argue that bending stresses promote lithostatic pore pressure to occur in the depth range of 7–15 km, causing the effective strength of the fault to vanish, and locally favoring creep. Our results suggest for the first time that earthquake cycles along a major plate boundary may be influenced by convective instabilities in the adjacent upper mantle.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1130/G34244.1 DOIArticle
http://geology.gsapubs.org/content/41/9/999PublisherArticle
http://geology.geoscienceworld.org/content/41/9/999.abstractPublisherArticle
Additional Information:© 2013 Geological Society of America. Manuscript received 18 November 2012; Revised manuscript received 16 April 2013; Manuscript accepted 5 May 2013. First published online July 11, 2013. This research was supported in part by a grant from the George and Betty Moore Foundation and INSU (Institut National des Sciences de l’Univers). This is contribution 104 of the California Institute of Technology (CalTech) Tectonics Observatory, and contribution 10016 of the Division of Geological and Planetary Science, CalTech. We thank three anonymous reviewers for the in-depth reviews that greatly improved the clarity of this manuscript.
Group:Caltech Tectonics Observatory
Funders:
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory104
Caltech Division of Geological and Planetary Sciences 10016
Record Number:CaltechAUTHORS:20130919-141723383
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130919-141723383
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41421
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Sep 2013 21:54
Last Modified:19 Sep 2013 21:54

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