Demonstration of Regional Discrimination of Eurasian Seismic Events UsingObservations at Soviet IRIS and CDSN Stations

摘要

This study has brought together a large, high-quality database of regionalsignals from Eurasian seismic events, including 38 underground nuclear explosions and 68 earthquakes, recorded at Soviet IRIS and CDSN stations. Characteristics of regional phases observed at each of the Soviet IRIS stations and their relation to propagation and source effects have been analyzed. The high quality of the signals indicates the strong potential of the stations for monitoring events throughout Eurasia. A variety of amplitude and spectral measurements have been performed on the regional signals to discern differences related to source type. We find here differences in Lg/P amplitude ratios and Lg/P spectral ratios between underground nuclear explosions and earthquakes. The fact that such differences are observed for explosions and earthquakes with practically identical propagation paths provides strong evidence that the observed behavior is dependent on source type. However, the regional phase amplitudes and spectral behavior also are affected by geologic structure along the propagation path. A methodology for identifying and adjusting the observations for such propagation effects is described. Similarity of signals for events of a common source type suggests that discriminants effective for some events are likely to work for others from the same general area.