Seismic source characteristics of Soviet peaceful nuclear explosions

During the period 1965 to 1988, the former Soviet Union (FSU) conducted ove r 120 peaceful nuclear explosions (PNE) at locations widely dispersed throu ghout the territories of the FSU. These explosions sample a much wider rang e of source conditions than do the historical explosions at the known nucle ar test sites and, therefore, seismic data recorded from these PNE tests pr ovide a unique resource for use in deriving improved quantitative bounds on the ranges of seismic signal characteristics which may require considerati on in global monitoring of the Comprehensive Test-Ban Treaty (CTBT). In thi s paper we summarize the results of a detailed statistical analysis of broa dband seismic data recorded at the Borovoye Geophysical Observatory from 21 of these PNE tests at regional distances extending from about 7 to 19 degr ees, as well as the results of theoretical waveform. simulation analyses of near-regional (Delta < 25 km) seismic data observed from a selected sample of nine of these PNE tests. The results of these analyses have been found to be consistent with those of previous teleseismic investigations in that they indicate that the seismic source coupling efficiencies are very simila r for explosions in a wide variety of hardrock and water-saturated media, w hile explosions in water-saturated clay are observed to have significantly higher coupling efficiencies. Moreover, the scaling of the seismic source f unction with explosion yield and depth of burial inferred from these analys es of the Soviet PNE data are shown to be generally consistent with the pre dictions of the Mueller/Murphy source model. These results suggest that the Mueller/Murphy source model can provide a reasonable basis for estimating the expected variation in regional phase spectral composition over a wide r ange of nuclear source conditions of potential interest in CTBT monitoring.