| Abstract: | In order to identify whether observed seismic signals are generated by an underground nuclear explosion or an earthquake, it is adequate to rely on one efficient identifier that provides a reasonably good clue in an unambiguous way. Although it is generally accepted that multi-station, multi-parameter discrimination can provide separation between explosions and earthquakes, it has been observed that cases do arise where signal characteristics cannot be established distinctly and satisfactorily. In the so-called “difficult” cases which are associated with some ambiguity in deducing the nature of the source using single-station seismograms, it is shown in this paper that a reliable estimate of source depth proves extremely useful. Out of the eleven typical examples of “not-easy-to-discriminate” events recorded at the Gauribidanur short-period seismic array in Southern India, seven could be successfully identified as earthquakes and the remaining four as probable underground explosions on the basis of focal-depth estimates from multi-station data. |
