THE EFFECT OF SHOTPOINT MEDIUM ON SEISMIC COUPLING

Geophysics ◽  
1961 ◽  
Vol 26 (6) ◽  
pp. 765-771
Author(s):  
W. M. Adams ◽  
L. M. Swift
Keyword(s):  
Seismic Waves ◽  
Surrounding Medium ◽  
Free Field ◽  
Field Measurements ◽  
Test Site ◽  
Salt Dome ◽  
Nevada Test Site ◽  
Overburden Pressure ◽  
Elastic Zone ◽  
Seismic Coupling

Two experiments on the coupling of seismic waves to the surrounding medium have been conducted. One was performed at two different overburden depths in a tunnel complex at the Nevada Test Site in the Oak Spring Tuff. The other was done at a depth of 800 ft in the Carey Salt Mine at the Winnfield Salt Dome near Winnfield, Louisiana. Free‐field measurements within 400 ft of the chemical charges indicate that three to four times more energy was propagated into the elastic zone in the tuff than in the salt. There is some indication that in tuff the amount of energy transmitted into the elastic zone was dependent upon the lithostatic overburden pressure. Increasing the overburden pressure by a factor of about five almost quadrupled the energy propagated into the elastic zone.

Comparison of seismic waves generated by different types of source

1963 ◽  
Vol 53 (5) ◽  
pp. 965-978 ◽  
Author(s):  
David E. Willis
Keyword(s):  
Seismic Waves ◽  
Nuclear Explosion ◽  
Test Site ◽  
Frequency Content ◽  
Nevada Test Site ◽  
Different Types ◽  
The Waves ◽  
Source Duration ◽  
Lower Frequencies

Abstract A comparison of the seismic waves generated by a nuclear explosion and an earthquake is discussed. The epicenter of the earthquake was located within the Nevada Test Site. Both events were recorded at the same station with the same type of equipment. The earthquake waves contained slightly lower frequency than the waves generated by the nuclear shot. The early P phases of the shot had larger amplitudes while the phases after Pg for the earthquake were larger. Seismic waves from collapses were generally found to be composed of lower frequencies than the waves from the original shot. Aftershocks of the Hebgen Lake earthquake were found to generate seismic waves whose frequency content was related to the magnitude of the aftershock. Spectral differences in quarry shot recordings that correlate with source duration times are also discussed.

SEISMIC DECOUPLING FOR EXPLOSIONS IN SPHERICAL UNDERGROUND CAVITIES

Geophysics ◽  
1961 ◽  
Vol 26 (6) ◽  
pp. 772-799 ◽  
Author(s):  
William M. Adams ◽  
DeWitt C. Allen
Keyword(s):  
Spherical Cavity ◽  
Seismic Waves ◽  
Free Field ◽  
Salt Mine ◽  
Cavity Pressure ◽  
Frequency Range ◽  
Overburden Pressure ◽  
Underground Cavities ◽  
Order Of Magnitude ◽  
Surface Measurements

A series of paired explosions in a salt mine near Winnfield, Louisiana, has been conducted to test a theory by A. L. Latter concerning seismic decoupling by underground cavities. The theory predicted a decoupling of 130. Free‐field and surface measurements from an explosion in either a 6‐ft‐ or a 15‐ft‐radius spherical cavity were compared with similar measurements from a completely tamped explosion of equal size. Shot sizes were from 20 pounds to a ton. Surface measurements were made out to 100 km and covered the frequency range from 0.05 to 100 cps. The experiment confirmed that decoupling does occur. For explosions that produce an average cavity pressure up to one‐fifth and possibly more of the lithostatic overburden pressure, seismic waves were decoupled by more than 100, i.e., two orders of magnitude. Even for explosions producing an average cavity pressure of six times the lithostatic overburden pressure, the seismic waves were decoupled by 20—more than a full order of magnitude. Minimum decoupling factors as a function of frequency are presented.

Geodetic determination of strain at the Nevada Test Site following the Handley event

1974 ◽  
Vol 64 (1) ◽  
pp. 115-129
Author(s):  
J. C. Savage ◽  
W. T. Kinoshita ◽  
W. H. Prescott
Keyword(s):  
Large Amplitude ◽  
Seismic Waves ◽  
Nuclear Explosion ◽  
Test Site ◽  
Nevada Test Site ◽  
Ground Zero ◽  
Overall Response ◽  
Final Configuration ◽  
East West

abstract Repeated surveys of a trilateration network (aperture greater than 20 km) centered on ground zero for the HANDLEY event, a nuclear explosion at the Nevada Test Site with yield in excess of 1 megaton, suggest that the explosion induced an east-west extension of the network by more than 50 mm. In the year following the detonation, this deformation reversed such that the final configuration represented a small east-west contraction from the pre-HANDLEY state. In the subsequent 2-year period, only minor deformation was detected. Thus, the overall response of Pahute Mesa may be described as stable. The explosion-induced deformation is thought to be partly due to slip on faults driven by the large-amplitude seismic waves from the explosion. The mechanism of the postshot relaxation is not understood.

The effect of Yucca Fault on seismic wave propagation

1971 ◽  
Vol 61 (3) ◽  
pp. 697-706 ◽  
Author(s):  
Walter W. Hays ◽  
John R. Murphy
Keyword(s):  
Wave Propagation ◽  
Seismic Wave ◽  
Seismic Waves ◽  
Low Frequency ◽  
Test Site ◽  
Seismic Wave Propagation ◽  
Nevada Test Site ◽  
Basement Rocks ◽  
Geological Discontinuity ◽  
Frequency Components

abstract Yucca Fault is a major structural feature of Yucca Flat, a well-known geological province of the Nevada Test Site (NTS). The trace of the Fault extends north-south over a distance of about 32 km. The fault plane is nearly vertical and offsets Quaternary alluvium, Tertiary volcanic tuffs and pre-Cenozoic basement rocks (quartzites, shales and dolomites) with relative down displacement of several hundred feet on the east side of the fault. Data recorded from the CUP underground nuclear detonation in Yucca Flat typify the effect of the fault on near-zone (i.e., inside 10 km) seismic wave propagation. The effect of the fault is frequency dependent. It affects the frequency components (3.0, 5.0, 10.0 Hz) of the seismic waves which have characteristic wavelengths in the order of the geological discontinuity. Little or no effect is observed for low-frequency components (0.5, 1.0 Hz) which have wave-lengths exceeding the dimensions of the geological discontinuity. The effect of the fault does not represent a safety problem.

Travel times and amplitudes of principal body phases recorded from gnome

1962 ◽  
Vol 52 (5) ◽  
pp. 1057-1074 ◽  
Author(s):  
Carl Romney ◽  
Billy G. Brooks ◽  
Robert H. Mansfield ◽  
Dean S. Carder ◽  
James N. Jordan ◽  
...  
Keyword(s):  
United States ◽  
Seismic Waves ◽  
Test Site ◽  
The United States ◽  
Body Waves ◽  
Travel Times ◽  
Eastern United States ◽  
Nevada Test Site ◽  
Short Period ◽  
The Difference

abstract gnome, an undergound nuclear explosion in salt near Carlsbad, New Mexico, produced seismic waves which were recorded widely throughout the United States and at a few foreign stations. The travel times of P were strongly dependent on the path of propagation, and were as much as 12 seconds earlier in the eastern United States than at equivalent distances in the western part of the United States. At the few stations more distant than 25°, P was about 2 seconds earlier than predicted by the Jeffreys-Bullen table for surface focus. Amplitudes of Pn were similarly dependent upon the path of propagation; although the measurements showed great scatter, amplitudes to the east were generally larger than those to the west. Pn travel time and amplitude anomalies suggest a systematic relationship to crustal thickness. There is evidence from the difference in the speeds and attenuation rates that Lg and P are not transmitted along analogous paths through the crust. Short period body waves were two or three times larger than expected from an explosion of the same energy in tuff at the Nevada Test Site. Surface waves, however, were relatively weak compared with explosions of similar yield in tuff.

Elastic wave propagation in heterogeneous media

1970 ◽  
Vol 60 (3) ◽  
pp. 769-784 ◽  
Author(s):  
Paul R. Beaudet
Keyword(s):  
Wave Propagation ◽  
Wave Equation ◽  
Seismic Waves ◽  
Heterogeneous Media ◽  
Heterogeneous Medium ◽  
Test Site ◽  
Nuclear Test ◽  
Field Observations ◽  
Nevada Test Site ◽  
Test Program

Abstract The wave equation is solved for the ensemble average of particle displacements produced by an explosion. The explosion is assumed to occur in a finite cavity in an infinite heterogeneous medium. The solution is applied to the seismic waves generated by an underground nuclear detonation. Field observations from the underground nuclear test program at the Nevada Test Site are in qualitative agreement with the theory.

Properties of Oak Spring formation in Area 12 at the Nevada Test Site

1959 ◽  
Author(s):  
W.H. Diment ◽  
R.E. Wilcox ◽  
G.V. Keller ◽  
E. Dobrovolny ◽  
F.C. Kracek ◽  
...  
Keyword(s):  
Test Site ◽  
Nevada Test Site
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