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On the layer of relatively low wave velocity at a depth of about 80 kilometers

Gutenberg, B. (1948) On the layer of relatively low wave velocity at a depth of about 80 kilometers. Bulletin of the Seismological Society of America, 38 (2). pp. 121-148. ISSN 0037-1106. doi:10.1785/BSSA0380020121.

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More than twenty years ago, the author (Gutenberg, 1926) pointed out that the longitudinal waves of shallow earthquakes decrease considerably in amplitude at epicentral distances between a few (say 2) degrees and about 15 degrees. At greater distances the amplitudes become again rather large, at 16° epicentral distance about as large as at 2°. With further increase in epicentral distance the amplitudes decrease slowly, The whole phenomenon was interpreted as due to a decrease in wave velocity at a depth between 70 and 80 km. Further investigations (Gutenberg and Richter, 1931; 1935, pp. 335-343; 1939a; Gutenberg, 1945a; 1945c, pp. 126-127) indicate that the decrease in velocity must be rather small, that the shadow zone is less significant in earthquakes which start at a depth of 150 to 250 km. and is absent in earthquakes originating at a depth of more than about 300 km.

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Additional Information:Copyright © 1948 by the Seismological Society of America. Manuscript received for publication December 11, 1947.
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Balch Graduate School of the Geological Sciences420
Issue or Number:2
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47728
Deposited By: George Porter
Deposited On:31 Jul 2014 21:43
Last Modified:28 Jan 2022 16:10

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