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Applications of attenuation tomography to Imperial Valley and Coso-Indian Wells Region, southern California

Ho-Liu, Phyllis and Kanamori, Hiroo and Clayton, Robert W. (1988) Applications of attenuation tomography to Imperial Valley and Coso-Indian Wells Region, southern California. Journal of Geophysical Research B, 93 (B9). pp. 10501-10520. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20121016-103928185

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Abstract

Spatial variations in seismic wave attenuation were tomographically imaged from observed S to P wave amplitude ratios in the Imperial Valley and Coso-Indian Wells regions of southern California. In the Coso-Indian Wells region a highly attenuating body (S wave quality factor Q_β ≈ 30) coincides with a slow P wave anomaly mapped by Walck and Clayton (1987). This coincidence suggests the presence of a 3- to 5-km depth magmatic or hydrothermal body in the Indian Wells region. In the Imperial Valley, slow P wave travel time anomalies and highly attenuating S wave anomalies were found in the Brawley seismic zone at a depth of 8–12 km. The effective S wave quality factor is very low (Q_β ≈ 20), and the P wave velocity is 10% slower than the surrounding areas. These results suggest either magmatic or hydrothermal intrusions, or fractures at depth, possibly related to active shear in the Brawley seismic zone. This attenuation tomographic technique is shown to be useful in delineating the spatial variations in seismic wave attenuation and in estimating the effective seismic quality factor of attenuation anomalies.


Item Type:Article
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http://dx.doi.org/10.1029/JB093iB09p10501 DOIUNSPECIFIED
http://www.agu.org/pubs/crossref/1988/JB093iB09p10501.shtmlPublisherUNSPECIFIED
Additional Information:© 1988 American Geophysical Union. Received 18 March 1987; accepted 6 March 1988. We thank Chris Sanders for valuable suggestions in the early stage of this study and providing us with the Coso data set and Marianne Walck for providing us with the results obtained in the Coso-Indian Wells study (Figure 7). We also thank Christof Stork for supplying the three-dimensional ray-tracing code. Discussions with Art Frankel, Carl Johnson, Kerry Sieh, Richard Stead, and John Vidale have been very helpful. We also thank Luciana Astiz, E. Kissling, Harold Magistrale, William Menke, Richard Stead, John Vidale, and two anonymous reviewers for reviewing the manuscript. This work is supported by USGS grant 14-08-0001-G1171 and in part by a grant from the Keck Foundation. Contribution no. 4437, from the Division of Geological and Planetary Sciences, California Institute of Technology.
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USGS14-08-0001-G1171
Keck FoundationUNSPECIFIED
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Caltech Division of Geological and Planetary Sciences4437
Record Number:CaltechAUTHORS:20121016-103928185
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20121016-103928185
Official Citation:Ho-Liu, P., H. Kanamori, and R. W. Clayton (1988), Applications of attenuation tomography to Imperial Valley and Coso-Indian Wells Region, southern California, J. Geophys. Res., 93(B9), 10,501–10,520, doi:10.1029/JB093iB09p10501
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34917
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:17 Oct 2012 18:37
Last Modified:27 Dec 2012 02:52

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