Simulation and Decomposition of Multiple Explosions

The purpose of the study is to develop procedures for using seismic measurements to verify the number and yields of individual explosions making up a multiple event. Multiple explosion seismograms are simulated by straightforward summations of single explosion records. Several types of multiple explosions are simulated. These include closely spaced equal yield explosions (no consideration given to propagation path effects between explosions and receiver) and relatively more widely spaced explosions (propagation path effects included) of varying yields. The data employed are principally close-in seismic recordings of the Nevada Test Site explosions obtained from Sandia Laboratories in Albuquerque, New Mexico. Decomposition of the simulated multiple explosion records is accomplished using a series of narrow-band filters with center frequencies ranging from 3 to 100 Hz. In general, our results show that the narrow-band filter technique is able to achieve accurate time separation and amplitude scaling. The limitation on the technique is essentially the requirement for the presence of sufficient signal energy at frequencies greater than about 3.5 times the inverse of the lag time between arriving signals.