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Unified Structural Representation of the southern California crust and upper mantle

Shaw, John H. and Plesch, Andreas and Tape, Carl and Suess, M. Peter and Jordan, Thomas H. and Ely, Geoffrey and Hauksson, Egill and Tromp, Jeroen and Tanimoto, Toshiro and Graves, Robert and Olsen, Kim and Nicholson, Craig and Maechling, Philip J. and Rivero, Carlos and Lovely, Peter and Brankman, Charles M. and Munster, Jason (2014) Unified Structural Representation of the southern California crust and upper mantle. Earth and Planetary Science Letters, 415 . pp. 1-15. ISSN 0012-821X. doi:10.1016/j.epsl.2015.01.016.

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We present a new, 3D description of crust and upper mantle velocity structure in southern California implemented as a Unified Structural Representation (USR). The USR is comprised of detailed basin velocity descriptions that are based on tens of thousands of direct velocity (Vp, Vs) measurements and incorporates the locations and displacement of major fault zones that influence basin structure. These basin descriptions were used to developed tomographic models of crust and upper mantle velocity and density structure, which were subsequently iterated and improved using 3D waveform adjoint tomography. A geotechnical layer (GTL) based on Vs30 measurements and consistent with the underlying velocity descriptions was also developed as an optional model component. The resulting model provides a detailed description of the structure of the southern California crust and upper mantle that reflects the complex tectonic history of the region. The crust thickens eastward as Moho depth varies from 10 to 40 km reflecting the transition from oceanic to continental crust. Deep sedimentary basins and underlying areas of thin crust reflect Neogene extensional tectonics overprinted by transpressional deformation and rapid sediment deposition since the late Pliocene. To illustrate the impact of this complex structure on strong ground motion forecasting, we simulate rupture of a proposed M 7.9 earthquake source in the Western Transverse Ranges. The results show distinct basin amplification and focusing of energy that reflects crustal structure described by the USR that is not captured by simpler velocity descriptions. We anticipate that the USR will be useful for a broad range of simulation and modeling efforts, including strong ground motion forecasting, dynamic rupture simulations, and fault system modeling. The USR is available through the Southern California Earthquake Center (SCEC) website (

Item Type:Article
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URLURL TypeDescription
Tape, Carl0000-0003-2804-7137
Hauksson, Egill0000-0002-6834-5051
Tromp, Jeroen0000-0002-2742-8299
Additional Information:© 2015 Elsevier B.V. Received 18 August 2014, Revised 15 January 2015, Accepted 19 January 2015, Available online 4 February 2015. Editor: P. Shearer. The authors thank Walter Mooney, Peter Shearer, and an anony-mous reviewer for constructive comments that helped to im-prove the manuscript. This work was supported by the Southern California Earthquake Center, the National Science Foundation, and the U.S. Geological Survey. SCEC is funded by NSF Cooperative Agreement EAR-1033462 and USGS Cooperative Agreement G12AC20038. This work was also supported through NSF awards EAR-1226343 titled “Geoinformatics: Community Computational Platforms for Developing Three-Dimensional Models of Earth Struc-ture” and EAR-1349180 titled “Community Computational Plat-forms for Developing Three-Dimensional Models of Earth Structure, Phase II.” The SCEC contribution number for this paper is 2068.
Group:Seismological Laboratory, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Southern California Earthquake CenterUNSPECIFIED
Subject Keywords:velocity structure; fault models; southern California; tomography; seismic wave propagation; strong ground motions
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Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center2068
Record Number:CaltechAUTHORS:20150409-151104225
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Official Citation:John H. Shaw, Andreas Plesch, Carl Tape, M. Peter Suess, Thomas H. Jordan, Geoffrey Ely, Egill Hauksson, Jeroen Tromp, Toshiro Tanimoto, Robert Graves, Kim Olsen, Craig Nicholson, Philip J. Maechling, Carlos Rivero, Peter Lovely, Charles M. Brankman, Jason Munster, Unified Structural Representation of the southern California crust and upper mantle, Earth and Planetary Science Letters, Volume 415, 1 April 2015, Pages 1-15, ISSN 0012-821X, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56557
Deposited By: Ruth Sustaita
Deposited On:10 Apr 2015 16:37
Last Modified:10 Nov 2021 21:00

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