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Published September 2018 | Supplemental Material + Published
Journal Article Open

Imaging the eastern Trans‐Mexican Volcanic Belt with ambient seismic noise: evidence for a slab tear

Abstract

The eastern sector of the Trans‐Mexican Volcanic Belt (TMVB) is an enigmatic narrow zone that lies just above where the Cocos plate displays a sharp transition in dipping angle in central Mexico. Current plate models indicate that the transition from flat to steeper subduction is continuous through this region, but the abrupt end of the TMVB suggests that the difference in subduction styles is more likely to be accommodated by a slab tear. Based on a high‐resolution shear wave velocity and radial anisotropy model of the region, we argue that a slab tear within South Cocos can explain the abrupt end of the TMVB. We also quantify the azimuthal anisotropy beneath each seismic station and present a well‐defined flow pattern that shows how mantle material is being displaced from beneath the slab to the mantle wedge through the tear in the subducted Cocos plate. We suggest that the toroidal mantle flow formed around the slab edges is responsible for the existence of the volcanic gap in central Mexico. Moreover, we propose that the temperature increase caused by the influx of hot, less‐dense mantle material flowing through the tear to the Veracruz area may have significant implications for the thermomechanical state of the subducted slab, and explain why the intermediate‐depth seismicity ends suddenly at the southern boundary of the Veracruz basin. The composite mantle flow formed by the movement of mantle material through the slab tears in western and southern Mexico may be allowing the Cocos plate to rollback in segments.

Additional Information

© 2018 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Received 16 MAR 2018; Accepted 18 AUG 2018; Accepted article online 22 AUG 2018; Published online 13 SEP 2018. This research was supported by NSF, EAR‐1645063 award. Our recognition is extended to the DGAPA‐PAPIIT IN105816 and CONACYT 177676 projects for maintaining the GECO Network. Our recognition is extended to the DGAPA‐PAPIIT IN105816, CONACYT 270544, and CONACYT 177676 projects for financing and maintaining the GECO Network. SSN data were obtained by the Servicio Sismológico Nacional (México), and we thank its personnel for station maintenance, data acquisition, and distribution (SSN, 2017). We also thank the Centro de Ciencias de la Tierra de la Universidad Veracruzana (CCTUV) and the Civil Protection authorities of Veracruz (SPC‐VER) for maintaining the UV network. We are grateful to Michael Brudzinski, Enrique Cabral‐Cano, and Alejandra Arciniega‐Ceballos for providing access to OXNET data. We also thank the IRIS‐PASSCAL Instrumentation Center for making the data available. Figures were made using the Generic Mapping Tools v.4.5.9 (www.soest.hawaii.edu/gmt, last accessed November 2017; Wessel and Smith, 1998). We gratefully thank Zack Spica and Sara Dougherty for providing their insight and expertise throughout the development of this work. We are also very grateful to Martha Savage and two anonymous reviewers for their careful and constructive suggestions. The final shear wave velocity and radial anisotropy models can be downloaded from https://github.com/JorgeCastillo90/Paper-2018JB015783R.git.

Attached Files

Published - Castellanos_et_al-2018-Journal_of_Geophysical_Research_3A_Solid_Earth.pdf

Supplemental Material - jgrb53003-sup-0001-supplementary.pdf

Supplemental Material - jgrb53003-sup-0002-supplementary.xlsx

Supplemental Material - jgrb53003-sup-0003-supplementary.xlsx

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Additional details

Created:
August 21, 2023
Modified:
October 18, 2023