Ground motion prediction method for simultaneously detonated multiple underground nuclear explosives

The problem of predicting the seismic signals generated by the simultaneous detonation of a multiple array of underground explosions is considered. A method is proposed whereby the multiple explosion signal or signal parameters may be synthesized from the single explosion signal or signal parameters. This method utilizes the superposition principle of elastic theory and the wave properties of seismic signals to construct a "coherency transfer function" essential to the synthesizing process. Both intuition and experience indicate that signals from multiple explosives can interfere either constructively or destructively. This analytical method is shown to be a good mathematical model by accurately predicting amplitudes for both cases. The method is applied to the results of several single and row charge cratering events and the calculations are compared to measured results. It is shown that when applied to peak amplitudes of velocity, this prediction method gives good agreement with experimental results for both simultaneous and sequential detonations with relatively short time delays. The results indicate that the simultaneous detonation of five close-spaced explosives in the 100-kt yield range detonated in an isotropic medium can result in larger amplitudes of motion than the detonation of a single explosive of equivalent total yield.