Raikes, Susan A. and Hadley, David M. (1979) The azimuthal variation of teleseismic P-residuals in southern California: Implications for upper-mantle structure. Tectonophysics, 56 (1-2). pp. 89-96. ISSN 0040-1951. doi:10.1016/0040-1951(79)90012-X. https://resolver.caltech.edu/CaltechAUTHORS:20171129-091030526
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Abstract
The azimuthal variation of teleseismic P-delays has been investigated for stations of the USGS-Caltech Southern California Seismographic Network. Normalized residuals show azimuthal variations as large as 1.2 s, and must be explained in terms of upper mantle structure. The observed azimuthal dependence implies the presence of a region of depressed velocity beneath the Imperial Valley, and regions of increased velocity below the Sierra Nevada, southwest Arizona, and much of the Transverse Ranges. The last is a major high velocity ridge-like structure, extending from a depth of ~40 km to over 100 km, which crosses, but is not offset by, the San Andreas Fault. This suggests that the plate boundary at depth may diverge from its surface expression. The horizontal shear resulting from the divergence of crust and mantle plate boundaries may be accommodated by a zone of decoupling associated with the regionally observed 7.8 km/s (P_n) layer.
| Item Type: | Article | |||||||||
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| Additional Information: | © 1979 Published by Elsevier B.V. Accepted 15 June 1978. We thank Hiroo Kanamori for many interesting and helpful discussions. This work was supported by the Earth Sciences Section of the National Science Foundation under grant number DES 75-03643 and by the U.S. Geological Survey under contract number 14-08-0001-15893. | |||||||||
| Group: | Seismological Laboratory | |||||||||
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| Issue or Number: | 1-2 | |||||||||
| DOI: | 10.1016/0040-1951(79)90012-X | |||||||||
| Record Number: | CaltechAUTHORS:20171129-091030526 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20171129-091030526 | |||||||||
| Official Citation: | Susan A. Raikes, David M. Hadley, The azimuthal variation of teleseismic P-residuals in southern California: Implications for upper-mantle structure, In Tectonophysics, Volume 56, Issues 1–2, 1979, Pages 89-96, ISSN 0040-1951, https://doi.org/10.1016/0040-1951(79)90012-X. (http://www.sciencedirect.com/science/article/pii/004019517990012X) | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 83564 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Tony Diaz | |||||||||
| Deposited On: | 29 Nov 2017 17:35 | |||||||||
| Last Modified: | 15 Nov 2021 20:12 |
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