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Subducting slab ultra-slow velocity layer coincident with silent earthquakes in southern Mexico

Song, Teh-Ru Alex and Helmberger, Donald V. and Brudzinski, Michael R. and Clayton, Robert W. and Davis, Paul and Pérez-Campos, Xyoli and Singh, Shri K. (2009) Subducting slab ultra-slow velocity layer coincident with silent earthquakes in southern Mexico. Science, 324 (5926). pp. 502-506. ISSN 0036-8075. http://resolver.caltech.edu/CaltechAUTHORS:20090507-090314466

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Abstract

Great earthquakes have repeatedly occurred on the plate interface in a few shallow-dipping subduction zones where the subducting and overriding plates are strongly locked. Silent earthquakes (or slow slip events) were recently discovered at the down-dip extension of the locked zone and interact with the earthquake cycle. Here, we show that locally observed converted SP arrivals and teleseismic underside reflections that sample the top of the subducting plate in southern Mexico reveal that the ultra-slow velocity layer (USL) varies spatially (3 to 5 kilometers, with an S-wave velocity of ~2.0 to 2.7 kilometers per second). Most slow slip patches coincide with the presence of the USL, and they are bounded by the absence of the USL. The extent of the USL delineates the zone of transitional frictional behavior.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1126/science.1167595DOIUNSPECIFIED
http://www.sciencemag.org/cgi/content/abstract/324/5926/502PublisherUNSPECIFIED
Additional Information:© 2009 American Association for the Advancement of Science. 23 October 2008; accepted 20 February 2009. We thank S. Sacks, P. Silver, S. Shirey, M. Bostock, J.-P. Avouav, and V. Manea for helpful discussions; R. Engdahl provided the global relocated seismic catalog used in fig. S10. We thank CENS at UCLA for support and the entire MASE team for making the MASE data available. We thank H. Hinojosa-Prieto, E. Cabral-Cano, A. Arciniega, O. Diaz-Molina, and C. DeMets for sharing their work on episodic tremor and slip in Oaxaca. Incorporated Research Institutions for Seismology Data Management Center and Canadian National Data Centre provided the GEOSCOPE data and Yellowknife short-period data used in this analysis, respectively. Station UNM is operated and maintained by Servicio Sismológical Nacional. This work is partially supported by NSF grant EAR-0636012. This is Tectonic Observatory contribution 10015. T.-R.A.S. is supported by a Carnegie fellowship at the Department of Terrestrial Magnetism.
Group:Caltech Tectonics Observatory, Caltech Tectonics Observatory. MesoAmerican Subduction Experiment (MASE)
Funders:
Funding AgencyGrant Number
NSFEAR-0636012
Carnegie fellowshipUNSPECIFIED
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Caltech Tectonics Observatory10015
Record Number:CaltechAUTHORS:20090507-090314466
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20090507-090314466
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14176
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:11 May 2009 21:38
Last Modified:26 Dec 2012 10:59

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