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Geometry and seismic properties of the subducting Cocos plate in central Mexico

Kim, Y. and Clayton, R. W. and Jackson, J. M. (2010) Geometry and seismic properties of the subducting Cocos plate in central Mexico. Journal of Geophysical Research B, 115 . Art. No. B06310. ISSN 0148-0227. doi:10.1029/2009JB006942.

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The geometry and properties of the interface of the Cocos plate beneath central Mexico are determined from the receiver functions (RFs) utilizing data from the Meso America Subduction Experiment (MASE). The RF image shows that the subducting oceanic crust is shallowly dipping to the north at 15° for 80 km from Acapulco and then horizontally underplates the continental crust for approximately 200 km to the Trans-Mexican Volcanic Belt (TMVB). The crustal image also shows that there is no continental root associated with the TMVB. The migrated image of the RFs shows that the slab is steeply dipping into the mantle at about 75° beneath the TMVB. Both the continental and oceanic Moho are clearly seen in both images, and modeling of the RF conversion amplitudes and timings of the underplated features reveals a thin low-velocity zone between the plate and the continental crust that appears to absorb nearly all of the strain between the upper plate and the slab. By inverting RF amplitudes of the converted phases and their time separations, we produce detailed maps of the seismic properties of the upper and lower oceanic crust of the subducting Cocos plate and its thickness. High Poisson's and Vp/Vs ratios due to anomalously low S wave velocity at the upper oceanic crust in the flat slab region may indicate the presence of water and hydrous minerals or high pore pressure. The evidence of high water content within the oceanic crust explains the flat subduction geometry without strong coupling of two plates. This may also explain the nonvolcanic tremor activity and slow slip events occurring in the subducting plate and the overlying crust.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Kim, Y.0000-0002-1111-632X
Clayton, R. W.0000-0003-3323-3508
Jackson, J. M.0000-0002-8256-6336
Additional Information:© 2010 American Geophysical Union. Received 31 August 2009; accepted 25 January 2010; published 17 June 2010. This study was supported by the Gordon and Betty Moore Foundation through the Tectonics Observatory at Caltech and NSF award EAR 0609707. We thank Juan S. Payero for providing the NVT locations and the many volunteers who worked on the MASE experiment. This is contribution 108 from the Caltech Tectonics Observatory.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
NSFEAR 0609707
Subject Keywords:subduction; receiver function; inversion
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Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory108
Record Number:CaltechAUTHORS:20100713-105555426
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Official Citation:Kim, Y., R. W. Clayton, and J. M. Jackson (2010), Geometry and seismic properties of the subducting Cocos plate in central Mexico, J. Geophys. Res., 115, B06310, doi:10.1029/2009JB006942.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19026
Deposited By: Tony Diaz
Deposited On:13 Jul 2010 20:32
Last Modified:08 Nov 2021 23:49

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