Analysis of Ground Motion and Containment
ENVIRONMENTAL RESEARCH CORP ALEXANDRIAVA
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The pre-shot predictions and evaluations of ground motion, stemming and containment are presented and compared with the available observed data. The analysis of seismic data included corrections for frequency response of the instruments, derivation of non- recorded motions by differentiation and integration, and filtering of the seismic signals to derive amplitude-frequency relationships. Seismic data were available from stations located between 2 to 32 kilometers from surface zero. Observed ground motions were lower than expected from a coupled fully tamped explosion of equal size. The peak accelerations and velocities displayed high rates of attenuation compared to Salmon. Relatively small azimuthal variations were observed. Peak motions were associated with frequencies between 3 and 80 Hz. A noticeable decrease in frequency with increasing distance was observed. The purpose of Sterling was to test decoupling theory which predicts that seismic signals can be reduced by detonating a nuclear device in a large cavity. The observed decoupling effects were strongly frequency-dependent. At frequencies between 2 and 5 Hz, particle velocities were reduced by a factor of about 200. Outside this range, observed decoupling factors decreased exponentially with frequency. The observed frequency dependence of the decoupling factor was found to agree with decoupling theory. The prediction of containment and evaluation of the stemming plan were substantiated by the test results. No other post-shot data were available for comparison.
- Nuclear Explosions and Devices (Non-Military)