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The shadow of the Earth's core

Guttenberg, B. (1960) The shadow of the Earth's core. Journal of Geophysical Research, 65 (3). pp. 1013-1020. ISSN 0148-0227.

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There is very good agreement between the observed decrease in amplitudes of longitudinal waves diffracted at the boundary of the earth's core and corresponding theoretical results. Especially, no rapid decrease of amplitudes at the beginning of the shadow zone is to be expected. Theory and observations show that the amplitudes of diffracted short-period P waves decrease faster with distance in the shadow zone than those of longer waves. At epicentral distances of over 110° short-period diffracted P waves emerge gradually and their beginning can rarely be ascertained. Corresponding long-period waves arrive within the limits of error at the time calculated on the assumption of a straight-line travel-time curve. Amplitudes of waves diffracted from a caustic decrease rapidly with distance; this usually limits the range of their observation to roughly 10°. On the contrary, amplitudes of P waves diffracted at the core may be visible on records of a great earthquake at distances of 103° to 180°. Observations for diffracted S waves cover a much smaller range of distances, since S waves appear in a portion of seismograms which is disturbed by earlier motion. Otherwise, observations indicate similar behavior for diffracted P and S waves.

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Additional Information:© 1960 American Geophysical Union. Manuscript received November 19, 1959.
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Caltech Division of Geological and Planetary Sciences957
Issue or Number:3
Record Number:CaltechAUTHORS:20140917-132740477
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Official Citation:Guttenberg, B. (1960), The shadow of the Earth's core, J. Geophys. Res., 65(3), 1013–1020, doi:10.1029/JZ065i003p01013
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49787
Deposited By: Tony Diaz
Deposited On:18 Sep 2014 02:56
Last Modified:03 Oct 2019 07:17

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