Use of Time-Deformation Methods to Discriminate between Earthquakes and Explosions on the Basis of Lg Alone

In this article we introduce the use of time-transformation methods for analyzing signals with time-varying frequencies. We show that these techniques can be usefully applied to the Lg waves of earthquakes and explosions for purposes of deriving discriminants based on the Lg wave alone. Preliminary examination of the Lg waves from 10 earthquakes and 10 explosions recorded at the Mina, Nevada (mnv), station shows that frequencies are varying (decreasing) more systematically with time for explosions than for earthquakes. Use of a proposed discriminant produced excellent discrimination between the earthquakes and explosions analyzed.