ENERGY LIBERATED IN THE AFTERSHOCK SEQUENCE OF AN EXPLOSION

Abstract

Rock blasting often produces aftershock sequences whose duration, intensity and total energy depend not only on the size of the shot, but also on the seismotectonic activity of the region. The aftershock sequence represents the process of relaxation of energy in the zone stimulated by the shot. The characteristics of aftershocks generally depend on the magnitude and distribution of the deformation energy imparted to the rock. Thus evaluation of the energy liberated in the aftershock sequence of a shot is a problem of principal importance. One method of determining the energy liberated by a tectonic earthquake is to estimate the energy of deformation of the crust in the critical state. The advantage of this method is that the estimate of the total energy liberated by the earthquake is independent of the theoretical or laboratory models of the focus. In this method the parameters of the earthquake are determined from its seismic traces. This method of determining the energy liberated in an earthquake was used to investigate the total energy of an aftershock sequence associated with an underground shot in anhydrite. The low energy liberated in the aftershock sequences of a shot, as estimated from the seismic trace in the epicentral zone, suggests that the energies of shots set off in aseismic rock bodies is converted to aftershock energy with a low efficiency.