Studies in decoupling. Annual report, March 1985-September 1987

Technical Report · Sat Nov 01 04:00:00 EST 1986

OSTI ID:5320432

Gupta, I N; McLaughlin, K L; Wagner, R A; McElfresh, T W; Marshall, M E

This report contains studies on seismic decoupling using Salmon, Sterling, and Pahute Mesa Nuclear Explosions, and on strain and frequency-dependent attenuation estimates in salt from Salmon and Sterling near-field recording. An understanding of the frequency dependence of decoupling is essential for monitoring nuclear explosions detonated in large underground cavities. Analysis of available data from the nuclear explosions Salmon and Sterling recorded at shot-receiver distances of 16, 32, and 27 km, confirmed earlier findings of Blandford and Woolson indicating: 1) reduced decoupling of Sterling at higher frequencies for both P and L, and (2) relatively greater decoupling of Sterling for lL than for P at high frequencies. In an attempt to understand why the frequency dependence of the decoupling ratio is different for P and Lg group, we examined the spectral content of Pn and Lg from 7 Pahute Mesa, NTS explosions covering a wide range of scaled depths and recorded at a common station, KN-UT. The spectral ratio Pn/Lg varied strongly with scaled depth, mainly due to significantly greater dependence on scaled depth of the spectra of Pn than of Lg. These results are in agreement with those from Salmon and Sterling. A possible reason for the decoupling at higher frequencies to be different for P and LG may be the greater scaled depth of decoupled shots. The Spectral ratio Pn/Lg may be useful in discriminating between decoupled (or overburied) and normal shots.

• Research Organization: Teledyne Geotech, Alexandria, VA (USA). Alexandria Labs.
• OSTI ID: 5320432
• Report Number(s): AD-A-188212/5/XAB; TGAL-86-08
• Country of Publication: United States
• Language: English

Related Subjects

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
450300* -- Military Technology
Weaponry
& National Defense-- Nuclear Explosion Detection
58 GEOSCIENCES
580201 -- Geophysics-- Seismology & Tectonics-- (1980-1989)
ATTENUATION
CHEMICAL REACTIONS
DECOUPLING
DEPTH
DETECTION
DIMENSIONS
DOCUMENT TYPES
EXPLOSIONS
MONITORING
NUCLEAR EXPLOSION DETECTION
NUCLEAR EXPLOSIONS
PROGRESS REPORT
REDUCTION
SEISMIC DETECTION
SEISMOLOGY
SPECTRA