Accession Number:

ADA230567

Title:

A Comparative Study of Regional Phases from Underground Nuclear Explosions at East Kazakh and Nevada Test Sites

Descriptive Note:

Rept. for Mar 1989-Feb 1990

Corporate Author:

TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS

Personal Author(s):

Report Date:

1990-09-01

Pagination or Media Count:

60.0

Abstract:

The spectral characteristics of regional phases from East Kazakh, USSR underground nuclear explosions are studied for their dependence on parameters such as m sub b generally related to shot depth and spatial location Shagan versus Degelen. The observed results are compared with those of the Nevada Test Site NTS, where the near-source conditions are better known. Pn and Lg from 25 Soviet nuclear shots recorded at the Chinese Digital Seismic Network CDSN station WMQ are analyzed by obtaining spectral and time domain measurements on each phase. The average amplitude ratio PnLg is found to be stable with mb but to vary strongly with frequency. For both Shagan and Yucca Flat explosions of similar yield, the reduction in amplitude with frequency is considerably larger for Lg than for Pn. At higher frequencies 3-7 Hz, the amplitude ratios PnLg for explosions from Shagan, Degelen, Pahute Mesa, and Yucca Flat test sites show significant differences that appear to be due to variations in their source medium velocities. Over the frequency range of about 0.5 to 5.0 Hz, PnLg increases by almost two orders of magnitude for the USSR shots and considerably less for the NTS shots. A possible explanation for the observed Lg spectra varying systematically with shot medium velocity is that Lg from USSR explosions is dominated by S whereas that from NTS shots includes contributions from both pS and S.

Subject Categories:

  • Seismic Detection and Detectors
  • Nuclear Weapons

Distribution Statement:

APPROVED FOR PUBLIC RELEASE