Abstract
IT would be premature to discuss at length the identification of S waves through the earth's core, announced by L. Bastings1, until the complete paper is available. Nevertheless, the failure of previous investigators to detect these waves with any confidence invites comment. If the waves are real, this result must be due either to their smallness and indistinctness, or to their nearness to others that must theoretically exist. The earthquake considered by Bastings has been also used by Miss I. Lehmann2; in her first paper, the P waves are considered, while the later one gives a diagram showing the readings of all from P to SS, at distances from 160° to 170°. The actual seismograms must be mainly the same as those read by Bastings. She proceeded by reading all the more striking movements without reference to their interpretation and afterwards comparing them with the theoretical times. Inspection of her diagram gives no impression that any movements besides the two branches of P, PP, SKS, PPP, SKKS, SKSP, PPS, and SS are capable of being traced over this range of distance, and even of these, SKS and SKSP show such a scatter from any smooth curve as to make the identifications doubtful. Presumably they are real but small or with indefinite commencements. She finds PPS early in comparison with Gutenberg's times, and this may be what Bastings has identified as S1. The difference between the observed times of this pulse and Gutenberg's calculated times for PPS may, however, arise from the errors of Gutenberg's times, which are reasonably good but still require some correction, and at present I am inclined to think that the pulse read is really PPS.
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NATURE, 134, 216, Aug. 11, 1934.
Gerlands Beiträge z. Geophysik, 26, 402–412; 1930. Verhandl. d. 5 Tagung d. Balt. Geodät. Komm., 192–212; 1931.
"The Earth”, 239; 1929. Mon. Not. Roy. Ast. Soc., Geoph. Suppl., 1, 371–383; 1926.
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JEFFREYS, H. State of the Earth's Central Core. Nature 134, 324 (1934). https://doi.org/10.1038/134324a0
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DOI: https://doi.org/10.1038/134324a0
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