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Crustal structure and temporal velocity change in southern California

Kanamori, Hiroo and Hadley, David (1975) Crustal structure and temporal velocity change in southern California. Pure and Applied Geophysics, 113 (1). pp. 257-280. ISSN 0033-4553.

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About twenty blasts are used to determine crustal structure and to monitor temporal seismic velocity changes in southern California. The shot time is determined up to 10 msec by using a disposable pick-up placed directly on the explosive. About 17 permanent stations and 20 temporary stations are used for the recordings. With a fast paper speed (typically 1 cm/sec) and the WWVB radio signals superposed on the seismic trace, absolute timing accuracy of up to 10 msec is achieved. A representative structure thus determined consists of a 4 km thick 5.5 km/sec layer underlain successively by 23.4 km thick 6.3 km/sec layer, 5.0 km thick 6.8 km/sec layer and 7.8 km/sec half space. The details of the lower crust are somewhat uncertain. This structure can explain the travel time data, corrected for the station and source elevations and for the station delays, to ±0.15 sec. Small but systematic temporal velocity changes up to 3% have been found for some of the profiles. If the effect of the migration of the shot point is small enough, these changes are larger than experimental errors and represent real temporal change in the material property between the shot point and the stations.

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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1975 Springer. (Received 2nd December 1974) We are very much indebted to RALPH GILMAN, FRANCIS LEHNER and his associates for the field operations. SHAWN BIEHLER and his colleagues at the University of California, Riverside, LEON TENG and his colleagues at the University of Southern California, and many graduate students at the Seismological Laboratory at Caltech helped us in the various aspects of the field program. DAVID JACKSON at the University of California at Los Angeles provided us with a reading at a UCLA station. HSI-PING LIV kindly measured the ultrasonic velocity of a bentonite sample from the Hector quarry. Our thanks go to Minnesota Mining and Manufacturing Co., General Portland Inc., California Portland Cement Co., Southwestern Portland Cement Co., Owl Rock Products Co., L. S. Hawley Corp., Baroid Division, N. L. Industries, Inc., Riverside Division, American Cement Corp., and Dr. Pierre St. Amand at U.S. Naval Ordnance Test Station at China Lake for kind cooperation in recording these blasts. This research was supported by Earthquake Research Affiliates, National Science Foundation Grant GA 29920, and US Geological Survey Contract 14-08-001-14563. Contribution No. 2530, Division of Geological Sciences, California Institute of Technology, Pasadena, California.
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Caltech Earthquake Research AffiliatesUNSPECIFIED
NSFGA 29920
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Caltech Division of Geological Sciences2530
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ID Code:59372
Deposited By: George Porter
Deposited On:11 Aug 2015 15:11
Last Modified:09 Mar 2020 13:18

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