Identification of earthquakes and explosions by use of teleseismic data

Criteria for achieving an order of magnitude discrimination between underground explosions and shallow-focus continental earthquakes are presented. The basis of all these criteria is the gross difference between earthquakes and explosions as regards their relative generation of short- and long-period waves. It is also shown that depth of focus of small events can be accurately determined either by use of master-controlled travel-time corrections or by determination of time of origin (Pg, S-P, etc.). Therefore, the basic problem for differentiating earthquakes and underground explosions of magnitude 4¾ or greater by seismic criteria has been solved. The remaining problems are the detection of long-period waves at low signal-to-noise ratios and the evaluation of the applicability of long-period identification criteria for low-magnitude events.