We have examined broadband waveforms from a large number of NTS explosions and earthquakes throughout the southwestern United States in order to characterize seismic sources. Explosions were found to be richer in coda energy than earthquakes. Most earthquakes show relatively little long-period (T>4 sec) coda energy and tend to be richer in long-period and shear-wave energy than explosions. We have developed several seismic discriminants based on these observations and our ...