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A two-dimensional P-SV hybrid method and its application to modeling localized structures near the core-mantle boundary

Wen, Lianxing and Helmberger, Donald V. (1998) A two-dimensional P-SV hybrid method and its application to modeling localized structures near the core-mantle boundary. Journal of Geophysical Research B, 103 (B8). 17,901-17,918. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20121129-110137879

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Abstract

A P-SV hybrid method is developed for calculating synthetic seismograms involving two-dimensional localized heterogeneous structures. The finite difference technique is applied in the heterogeneous region and generalized ray theory solutions from a seismic source are used in the finite difference initiation process. The seismic motions, after interacting with the heterogeneous structures, are propagated back to the Earth's surface analytically with the aid of the Kirchhoff method. Anomalous long-period SKS-SPdKS observations, sampling a region near the core-mantle boundary beneath the southwest Pacific, are modeled with the hybrid method. Localized structures just above the core-mantle boundary, with lateral dimensions of 250 to 400 km, can explain even the most anomalous data observed to date if S velocity drops up to 30% are allowed for a P velocity drop of 10%. Structural shapes and seismic properties of those anomalies are constrained from the data since synthetic waveforms are sensitive to the location and lateral dimension of seismic anomalies near the core-mantle boundary. Some important issues, such as the density change and roughness of the structures and the sharpness of the transition from the structures to the surrounding mantle, however, remain unresolved due to the nature of the data.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/98JB01276DOIUNSPECIFIED
http://www.agu.org/pubs/crossref/1998/98JB01276.shtmlPublisherUNSPECIFIED
Additional Information:© 1998 American Geophysical Union. Received 23 July 1997; revised January 15, 1998; accepted 9 April 1998. We thank R. Clayton for his assistance, X. Ding for providing the WKB code and E. Garnero for providing the data. We also thank D.L. Anderson, E. Brodsky, M. Gurnis, T. Melbourne, two anonymous reviewers, and an associate editor for reviews. This work was funded by NSF grants EAR-9316441 and EAR-9629279. Contribution 6211, Division of Geological and Planetary Sciences, California Institute of Technology.
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NSFEAR-9316441
NSFEAR-9629279
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Caltech Division of Geological and Planetary Sciences6211
Record Number:CaltechAUTHORS:20121129-110137879
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20121129-110137879
Official Citation:Wen, L. and D. V. Helmberger (1998), A two-dimensional P-SV hybrid method and its application to modeling localized structures near the core-mantle boundary, J. Geophys. Res., 103(B8), 17,901–17,918, doi:10.1029/98JB01276.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35729
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:29 Nov 2012 19:24
Last Modified:27 Dec 2012 03:05

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