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Spectrum of P and PcP in relation to the mantle-core boundary and attenuation in the mantle

Kanamori, Hiroo (1967) Spectrum of P and PcP in relation to the mantle-core boundary and attenuation in the mantle. Journal of Geophysical Research, 72 (2). pp. 559-571. ISSN 0148-0227.

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Spectrum analyses were made of the records of the short-period vertical component of P and PcP phases on seismograms of array stations at Tonto Forest, Arizona, for twenty-one earthquakes over the range Δ = 47° to 83°. Generally, as has been reported by other investigators, the trace amplitude ratio of PcP to P is significantly larger than the theoretical ratio. The pulse width of PcP is narrower than that of P. Both of these facts can be explained by taking into account an appropriate attenuation distribution in the mantle. Taking Q_β, Q for S waves, which has been determined by Anderson, Ben-Menahem, and Archambeau using different methods as a standard, the Q distribution for P waves, Q_a, can be determined as Q_a ≈ Q_β at the period of about 1 sec. A matrix method is applied to calculate the complex reflection coefficient of a transitional mantle-core boundary. Impulse responses calculated therefrom and comparison of the waveforms of P and PcP lead to the conclusion that the major discontinuity at the mantle-core boundary is sharp and is probably less than 1 km thick. The effect of a more gradual transition region superposed upon such a sharp discontinuity is also discussed. The possibility of the existence of a soft layer terminated by a sharp boundary cannot be totally ruled out.

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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:Copyright © 1967 by the American Geophysical Union. (Received July 2, 1966; revised September 22, 1966.) I am indebted to Dr. Don Anderson for critically reading the manuscript and offering suggestions for its improvement. Thanks are also extended to Dr. Francis Wu for the use of his computer program for the calculation of the complex reflection coefficient. I have benefited from many discussions with Drs. James Brune, Hewitt Dix, Lane Johnson, Stewart Smith, and Ta-Liang Teng. This research was partially supported by the Advanced Research Projects Agency and was monitored by the Air Force Office of Scientific Research under contract AF-49(638)-1337. Contribution 1412, Division of Geological Sciences, California Institute of Technology.
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Advanced Research Projects Agency (ARPA)UNSPECIFIED
Air Force Office of Scientific Research (AFOSR)AF-49(638)-1337
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Caltech Division of Geological Sciences1412
Issue or Number:2
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Official Citation:Kanamori, H. (1967), Spectrum of P and PcP in relation to the mantle-core boundary and attenuation in the mantle, J. Geophys. Res., 72(2), 559–571, doi:10.1029/JZ072i002p00559.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51462
Deposited By: George Porter
Deposited On:07 Nov 2014 23:03
Last Modified:09 Mar 2020 13:18

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