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A study of the seismic waves SKS and SKKS

Nelson, Robert L. (1954) A study of the seismic waves SKS and SKKS. Bulletin of the Seismological Society of America, 44 (1). pp. 39-55. ISSN 0037-1106.

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Arrival times, amplitudes, and periods of the seismic phases SKS and SKKS have been investigated for shallow, intermediate, and deep earthquakes recorded at Pasadena and Huancayo, Peru. New observed time-distance curves are constructed for depths of <60, 100, 200, and 600 kilometers. Travel times for the core have been calculated from shallow-shock time data. Slight modification of wave velocity just inside the core and of travel times within the core are suggested. Calculated travel times of SKS, SKKS, and SKKKS are in good agreement with observations. Energy parameters determined from observed amplitude/period ratios are found in only fair agreement with those calculated from theory. Observed energies are too large for most of the phase components and depths considered. The horizontal components of SKKS over the whole distance range, and of SKS at Δ ≦ 100° for all depths, yield observed energies less than those predicted by theory. Both discrepancies are at least qualitatively explained by a proposed nonspherical distribution of shear strain about the fault source, and by abnormal absorption in the outer 700 kilometers of the core. Anomalous observed energies, as functions of epicentral location, are also accounted for by the proposed nonspherical distribution of energy.

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Additional Information:Copyright © 1954, by the Seismological Society of America. Manuscript received for publication June 13, 1952. The writer is indebted to Professor Beno Gutenberg for suggestion of the problem and for many helpful criticisms during the course of the investigation and preparation of the manuscript. The suggestions and comments of Dr. Hugo Benioff and Professor Charles F. Richter on many phases of the problem have been helpful and inspiring. This study was carried on while the writer was the recipient of a fellowship granted by the Stanolind Oil and Gas Company, whose financial assistance is gratefully acknowledged. Detailed data, calculations, and results, as well as additional data on phase periods, multiplicity, and polarization are available in the thesis, on file at the California Institute of Technology, Pasadena.
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Stanolind Oil and Gas CompanyUNSPECIFIED
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Caltech Division of Geological Sciences598
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ID Code:48024
Deposited By: George Porter
Deposited On:06 Aug 2014 14:23
Last Modified:03 Oct 2019 06:59

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