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Seismic structure beneath the Gulf of California: a contribution from group velocity measurements

Di Luccio, F. and Persaud, P. and Clayton, R. W. (2014) Seismic structure beneath the Gulf of California: a contribution from group velocity measurements. Geophysical Journal International, 199 (3). pp. 1861-1877. ISSN 0956-540X. doi:10.1093/gji/ggu338.

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Rayleigh wave group velocity dispersion measurements from local and regional earthquakes are used to interpret the lithospheric structure in the Gulf of California region. We compute group velocity maps for Rayleigh waves from 10 to 150 s using earthquakes recorded by broad-band stations of the Network of Autonomously Recording Seismographs in Baja California and Mexico mainland, UNM in Mexico, BOR, DPP and GOR in southern California and TUC in Arizona. The study area is gridded in 120 longitude cells by 180 latitude cells, with an equal spacing of 10 × 10 km. Assuming that each gridpoint is laterally homogeneous, for each period the tomographic maps are inverted to produce a 3-D lithospheric shear wave velocity model for the region. Near the Gulf of California rift axis, we found three prominent low shear wave velocity regions, which are associated with mantle upwelling near the Cerro Prieto volcanic field, the Ballenas Transform Fault and the East Pacific Rise. Upwelling of the mantle at lithospheric and asthenospheric depths characterizes most of the Gulf. This more detailed finding is new when compared to previous surface wave studies in the region. A low-velocity zone in northcentral Baja at ∼28ºN which extends east–south–eastwards is interpreted as an asthenospheric window. In addition, we also identify a well-defined high-velocity zone in the upper mantle beneath central-western Baja California, which correlates with the previously interpreted location of the stalled Guadalupe and Magdalena microplates. We interpret locations of the fossil slab and slab window in light of the distribution of unique post-subduction volcanic rocks in the Gulf of California and Baja California. We also observe a high-velocity anomaly at 50-km depth extending down to ∼130 km near the southwestern Baja coastline and beneath Baja, which may represent another remnant of the Farallon slab.

Item Type:Article
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URLURL TypeDescription DOIArticle Information
Persaud, P.0000-0003-3462-7023
Clayton, R. W.0000-0003-3323-3508
Additional Information:© 2014 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. Accepted 2014 September 2. Received 2014 August 27; in original form 2013 June 21. We would like to thank J. Contreras, J. Gaherty, R. Negrete-Aranda, M. Pasyanos, J. O. Campos-Enríquez and F. Lin for the very constructive comments on different aspects of the manuscript. We also thank F. Pereira for his help in developing the tomographic code. We are grateful to B. Savage supplying his velocity model. Comments from two anonymous reviewers and the Editor W. Friederich contributed to improve the final version of the manuscript. Some figures were generated using GMT software (Wessel & Smith 1998).
Group:Seismological Laboratory
Subject Keywords:Surface waves and free oscillations; Seismic tomography; Dynamics of lithosphere and mantle; Crustal structure
Issue or Number:3
Record Number:CaltechAUTHORS:20150105-142549856
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Official Citation:F. Di Luccio, P. Persaud, and R. W. Clayton Seismic structure beneath the Gulf of California: a contribution from group velocity measurements Geophys. J. Int. (December, 2014) 199 (3): 1861-1877 doi:10.1093/gji/ggu338
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53193
Deposited By: Tony Diaz
Deposited On:06 Jan 2015 19:15
Last Modified:10 Nov 2021 19:49

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