Shear waves from a nuclear explosion in a salt cavity

1968 ◽  
Vol 58 (6) ◽  
pp. 2043-2051
Author(s):  
William R. Perret
Keyword(s):  
Particle Velocity ◽  
Nuclear Explosion ◽  
Shear Waves ◽  
Vertical Motion ◽  
Salt Dome ◽  
Explosive Source ◽  
Level Plane ◽  
Stable Cavity

ABSTRACT Shear waves have been resolved in records of acceleration and particle velocity resulting from the Sterling event which was a nuclear explosion (380 tons) within the stable cavity left by the Salmon detonation in the Tatum salt dome. These shear waves were strongest in records of vertical motion at stations in the shot-level plane, but were detectable in records from both vertical and horizontal radial gages above and below that elevation. No appreciable shear waves could be identified in records from shot-level gages oriented horizontally. All instruments involved in this study were situated within the salt dome at ranges between 166 and 660 meters from the explosive source. Shear waves carried over 95 per cent of the energy in vertical shot-level records, but they represented less than 11 per cent of the energy in horizontal radial shot-level records. Cause of the vertically polarized shear waves is considered to be vertical asymmetry at the source.

VSP measurement of shear‐wave velocities in consolidated and poorly consolidated formations

Geophysics ◽  
1992 ◽  
Vol 57 (12) ◽  
pp. 1583-1592 ◽  
Author(s):  
John O’Brien
Keyword(s):  
Shear Wave ◽  
Poisson’S Ratio ◽  
Mode Conversion ◽  
Shear Waves ◽  
Vertical Motion ◽  
Seismic Source ◽  
Poisson's Ratio ◽  
The Arctic ◽  
Wave Velocities ◽  
Shear Wave Velocities

Mode conversion in the subsurface can generate shear waves with sufficient amplitude so that they can be used to measure shear‐wave propagation effects. Significant mode conversion can occur even at near vertical incidence if there is sufficient contrast in Poisson’s ratio across the interface. This can be exploited to measure shear‐wave velocities in the underlying section in the course of vertical seismic profile (VSP) acquisition. The technique is effective even in poorly consolidated formations with low shear‐wave velocities where sonic waveform logging fails. Where shear‐wave velocity data are available from sonic waveform logs, the VSP data can be used to verify the wireline data and to calibrate these data to seismic frequencies. The technique is illustrated with a case study from the North Slope, Alaska, in which several shear‐wave events are observed propagating downward through the subsurface. The seismic source is a vertical‐motion vibrator; shear waves are generated via mode conversion in the subsurface and also radiated from the source at the surface, and they are observed with both far‐ and near‐source offsets. The shear‐wave events are strong even on the near‐offset data, which is attributed to the contrast in Poisson’s ratio at the interfaces where mode conversion occurs. The technique is not limited to the hard surfaces of the Arctic and should work in any well, either land or marine, that penetrates shallow interfaces where mode conversion can occur.

scholarly journals Strain Hardening in Salt—Results of the SALMON Experiment

1990 ◽  
Vol 112 (2) ◽  
pp. 145-148 ◽  
Author(s):  
L. A. Glenn
Keyword(s):  
Yield Strength ◽  
Strain Hardening ◽  
Nuclear Explosion ◽  
Fluid Pressure ◽  
Salt Dome ◽  
Pore Fluid ◽  
Laboratory Scale ◽  
Experimental Results ◽  
Pore Fluid Pressure

SALMON was a nuclear explosion in the Tatum salt dome, near Hattiesburg, Mississippi, that took place on October 22, 1964. Computational attempts to simulate the experimental results had been largely unsuccessful. Recent calculations suggest that the reason is that the salt yield strength is extremely sensitive to strain hardening. The hardening effect had not been observed in laboratory-scale measurements, which were not made at small enough strain levels and may not have been representative of in-situ pore-fluid pressure.

scholarly journals EARTH VIBRATIONS FROM A NUCLEAR EXPLOSION IN A SALT DOME

1967 ◽  
Author(s):  
W. V. Mickey ◽  
L. M. Lowrie ◽  
T. R. Shugart
Keyword(s):  
Nuclear Explosion ◽  
Salt Dome

scholarly journals Sedimentation of a dilute suspension of rigid spheres at intermediate Galileo numbers: the effect of clustering upon the particle motion

2014 ◽  
Vol 752 ◽  
pp. 310-348 ◽  
Author(s):  
Markus Uhlmann ◽  
Todor Doychev
Keyword(s):  
Particle Velocity ◽  
Settling Velocity ◽  
Fluid Velocity ◽  
Voronoi Tessellation ◽  
Density Ratio ◽  
Fluid Motion ◽  
Finite Size ◽  
Vertical Motion ◽  
Average Particle ◽  
Rigid Spheres

AbstractDirect numerical simulation of the gravity-induced settling of finite-size particles in triply periodic domains has been performed under dilute conditions. For a single solid-to-fluid-density ratio of 1.5 we have considered two values of the Galileo number corresponding to steady vertical motion ($\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\mathit{Ga}=121$) and to steady oblique motion ($\mathit{Ga}=178$) in the case of one isolated sphere. For the multiparticle system we observe strong particle clustering only in the latter case. The geometry and time scales related to clustering are determined from Voronoï tessellation and particle-conditioned averaging. As a consequence of clustering, the average particle settling velocity is increased by 12 % as compared with the value of an isolated sphere; such a collective effect is not observed in the non-clustering case. By defining a local (instantaneous) fluid velocity average in the vicinity of the finite-size particles it is shown that the observed enhancement of the settling velocity is due to the fact that the downward fluid motion (with respect to the global average) which is induced in the cluster regions is preferentially sampled by the particles. It is further observed that the variance of the particle velocity is strongly enhanced in the clustering case. With the aid of a decomposition of the particle velocity it is shown that this increase is due to enhanced fluid velocity fluctuations (due to clustering) in the vicinity of the particles. Finally, we discuss a possible explanation for the observation of a critical Galileo number marking the onset of clustering under dilute conditions.

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