Accession Number : AD0640842

Title :   AN EVALUATION OF A METHOD FOR FOCAL-DEPTH DETERMINATION OF SEISMIC DISTURBANCES FROM UNDERGROUND NUCLEAR EXPLOSIONS.

Descriptive Note : Special technical rept.,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF GEOLOGY AND GEOPHYSICS

Personal Author(s) : Lin,Jin-Long

Report Date : 15 JUL 1966

Pagination or Media Count : 109

Abstract : The Watson-Merdler method for determination of focal depths was applied to fourteen seismograms from underground nuclear explosions. Because the depths for blasts are less than 1 km, the true time delta t for the actual surface reflection was not tested. 200 cases where concentration ratio, C sub R, was greater than in the original seismogram and where the area under the seismogram was reduced were investigated. Causes which can produce simplification are: (1) Deconvolution removes the pP sequence from the seismogram. (2) Deconvolution removes PcP or some other sequence other than pP. (3) Deconvolution produces a larger maximum amplitude in the deconvolved seismogram than in the original. (4) Deconvolution diminishes amplitudes on the seismogram. (5) Deconvolution phases random noise so as to add to or subtract from the principal peaks of the seismic pulse. The doublet-function hypothesis for a seismogram is too simple and is therefore unrealistic. The simplicity criterion may identify many pulses in addition to the pP pulse on the seismogram. The Watson-Merdler method does not show promise to distinguish blasts from earthquakes. (Author)

Descriptors :   (*UNDERGROUND EXPLOSIONS, *SEISMIC WAVES), (*SEISMOLOGY, *NUCLEAR EXPLOSIONS), SEISMOGRAPHS, EPICENTERS, BLAST, EARTHQUAKES, COMPUTER PROGRAMMING

Subject Categories : Seismology

Distribution Statement : APPROVED FOR PUBLIC RELEASE