Contrasting with conclusions from laboratory experiments that the absorption coefficient k for amplitudes of elastic waves is proportional to 1/T, or, from theoretical considerations, that it should be proportional to 1/T or to 1/T2, observations of body waves through the mantle of the earth show little if any decrease in absorption with increasing period T. In teleseismic records S rarely shows periods of less than 4 seconds, while in P periods of 1 second are observed to the greatest distances. The value k = 0.06 per 1,000 km., found previously for P, P′P′ and P′P′P′ through the mantle and the core, is confirmed for P and PP and is found also for S in the mantle.

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