Seismic Detection Methods for Underground Explosions

Underground explosions are detectable at long ranges only by recording and analyzing seismic waves. The signals received are highly distorted as a result of multi-path propagation, dispersion, mode conversion, and scattering. The result is that signals from explosions tend to be similar to those recorded from thousands of small earthquakes which occur each year. The basic detection problem thus becomes one of sorting out suspicious events from the many natural events recorded. No way of identifying explosions by seismic means is now known, but methods of identifying a fair proportion of natural events exist and are being improved. The remaining occurrences in the suspicious category could be identified only if other kinds of information were available.