Seismic Source Characteristics of Soviet Peaceful Nuclear Explosions

Abstract

— During the period 1965 to 1988, the former Soviet Union (FSU) conducted over 120 peaceful nuclear explosions (PNE) at locations widely dispersed throughout the territories of the FSU. These explosions sample a much wider range of source conditions than do the historical explosions at the known nuclear test sites and, therefore, seismic data recorded from these PNE tests provide a unique resource for use in deriving improved quantitative bounds on the ranges of seismic signal characteristics which may require consideration in global monitoring of the Comprehensive Test-Ban Treaty (CTBT). In this paper we summarize the results of a detailed statistical analysis of broadband seismic data recorded at the Borovoye Geophysical Observatory from 21 of these PNE tests at regional distances extending from about 7 to 19 degrees, as well as the results of theoretical waveform simulation analyses of near-regional (Δ < 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 similar for explosions in a wide variety of hardrock and water-saturated media, while explosions in water-saturated clay are observed to have significantly higher coupling efficiencies. Moreover, the scaling of the seismic source function with explosion yield and depth of burial inferred from these analyses of the Soviet PNE data are shown to be generally consistent with the predictions 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 range of nuclear source conditions of potential interest in CTBT monitoring.