Seismic Energy from Explosions

Abstract

For underwater explosions it is shown that the amplitude of the first arrival of the ground wave should be proportional to W2/3, where W is the charge weight. Also that its frequency content should be independent of W. Of the total chemical energy of the explosive it is estimated that about 3 per cent is available in the frequency range 0–100 c/s. For underground explosions it is postulated that the radiated pressure pulse begins to obey infinitesimal strain theory once its impulse per unit area has decreased below a limiting value. This value is constant for a given rock type. From this it follows that the seismic amplitude should usually be directly proportional to W. But for high frequencies or very large charges it should become proportional to W2/3. These predictions are compared with observational data, both original and those previously published. They agree well for underground explosions. For underwater explosions the data are themselves inconsistent and more are needed.