HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) References Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by GUTENBERG, B. Articles by RICHTER, C. F. Search for Related Content GeoRef GeoRef Citation

On supposed discontinuities in the mantle of the Earth

SEISMOLOGICAL LABORATORY, PASADENA, CALIFORNIA

Abstract

Investigations of the Mexican shocks of January 2, 15, and 17, 1931, as recorded at stations in California have shown that the travel-time curve of the P-waves at distances between 9° and 15° is nearly a straight line. At these distances the amplitudes of the P-waves are very small, as is to be expected from theory. At greater distances dt/d decreases, and the amplitudes are larger. The data are not sufficient to decide whether the changes are abrupt or not. No S-waves could be found between 9° and 15°. The calculated velocities of the P-waves are near 8.2 kilometers per second at depths between 40 and 100 kilometers, increasing slightly with greater depths. It is possible that the velocity decreases very slightly at some depths between 40 and 80 kilometers, but there is no sign of any discontinuity at depths between 40 and more than 500 kilometers. The S-waves seem to be affected a little more at depths between 40 and 100 kilometers than the P-waves. It is not impossible that at some depth between 40 and 80 kilometers there is a transition from the crystalline to the glassy state.

This article has been cited by other articles:

				B. GUTENBERG On the layer of relatively low wave velocity at a depth of about 80 kilometers Bulletin of the Seismological Society of America, April 1, 1948; 38(2): 121 - 148. [Abstract] [PDF]

				P. BYERLY The first preliminary waves of the Nevada earthquake of December 20, 1932 Bulletin of the Seismological Society of America, January 1, 1935; 25(1): 62 - 80. [Abstract] [PDF]

				P. BYERLY The Texas earthquake of August 16, 1931 Bulletin of the Seismological Society of America, April 1, 1934; 24(2): 81 - 99. [Abstract] [PDF]

				V. C. STECHSCHULTE The Japanese earthquake of March 29, 1928, and the problem of depth of focus Bulletin of the Seismological Society of America, June 1, 1932; 22(2): 81 - 137. [PDF]