Yields of Underground Nuclear Explosions at Azgir and Shagan River, USSR and Implications for Identifying Decoupled Nuclear Testing in Salt.

摘要

Bodywave magnitudes, mb, are recomputed using station corrections for all known Soviet underground nuclear explosions at Shagan River and Azgir. The mb values for explosions of announced yield, Y, in various parts of the world in either hard rock or below the water table were normalized to the SW part of the Shagan River testing area using previously published values of t* and mb bias. The resulting relationship, mb = 4.48 + 0.79 logY, which includes yields published by Bocharov et al. (1989) for Shagan River, differs very little from a regression that does not include those data. Using magnitudes determined from Lg at NORSAR as a standard, the Shagan River site is divided into three subareas. Yields calculated from these revised mb values and from m(Lg) are much more consistent for the same explosion; each agrees closely with the yields published by Bocharov et al. for large explosions in 1971 and 1972 in the NE and SW parts of the testing area. Yields calculated by averaging determinations from Lg and body waves for 66 explosions have a high precision at 95% confidence (mean value 1. 14) for Y > 10 kt. The explosion of 23 July 1973 of Y = 193 kt is clearly the largest underground explosion at Shagan River. The newly calculated values provide strong evidence of clustering in the distribution of yields of Soviet tests. In a special study yields of Soviet nuclear explosions, nuclear tests in salt, decoupling, evasion