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Upper mantle surprises derived from the recent Virginia earthquake waveform data

Chu, Risheng and Helmberger, Don and Gurnis, Michael (2014) Upper mantle surprises derived from the recent Virginia earthquake waveform data. Earth and Planetary Science Letters, 402 . pp. 167-175. ISSN 0012-821X. doi:10.1016/j.epsl.2012.10.023.

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Recent high resolution regional waveform modeling reveals that the lithosphere beneath the North American craton is subdivided into an upper nearly uniform layer and a lower layer with a high velocity gradient. The boundary occurs at about a depth of 115 km and is responsible for 8° discontinuity in seismic record sections that is often observed in craton environments. Unexpectedly, we find seismic velocities in the lower layer significantly reduced along a corridor from the New Madrid rift zone to Virginia. This reduced velocity in the lower lithosphere may be associated with a possible historic hotspot activity. We also find a well developed X-discontinuity that we model as a ∼3% increase in P velocity starting at a depth of ∼290 km. These anomalous features transition into a nearly 1D craton structure to the north with a strong low-velocity anomaly just above the 410 discontinuity along an east–west boundary. The latter two features may be relics of structures formed from the descending Farallon plate between Late Cretaceous and Early Tertiary.

Item Type:Article
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Gurnis, Michael0000-0003-1704-597X
Additional Information:© 2012 Elsevier B.V. Accepted 26 October 2012. Available online 22 November 2012. Editor: P. Shearer. We would like to thank two anonymous reviewers. Their suggestions and comments made significant improvements to the manuscript. This work was partially supported by the Gordon and Betty Moore Foundation through Tectonic Observatory, California Institute of Technology. RC and DVH are partially supported by the National Science Foundation through Grant no. EAR-1053064.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Caltech Tectonics ObservatoryUNSPECIFIED
Subject Keywords:lithosphere; upper mantle; X discontinuity
Record Number:CaltechAUTHORS:20141002-102959367
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Official Citation:Risheng Chu, Don Helmberger, Michael Gurnis, Upper mantle surprises derived from the recent Virginia earthquake waveform data, Earth and Planetary Science Letters, Volume 402, 15 September 2014, Pages 167-175, ISSN 0012-821X, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50166
Deposited By: Ruth Sustaita
Deposited On:02 Oct 2014 17:55
Last Modified:10 Nov 2021 18:52

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