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Underground Nuclear Explosions at Azgir, Kazakhstan, and Implications for Identifying Decoupled Nuclear Testing in Salt

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Technical rept.

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Bodywave magnitudes, mb are recomputed for 17 nuclear explosions with yields of about 0.01 to 100 kilotons kt at Azgir in western Kazakhstan. Station corrections were developed for Azgir using larger events and then applied in recomputing magnitude of other explosions. Revised values of mb for three tamped fully coupled explosions in salt at Azgir and one at Orenburg of announced yield, Y, were used to obtain the relationship, mb 4.425 0.832 log Y. Salt is one of the best coupling geological media for generating seismic waves from underground nuclear explosions. In a special study made of the Azgir explosion of 1.1 kt of 1966 mb was determined for 16 stations at 4.52 or - . 06. For purposes of appreciating the detection capability of a given seismic network, it is important to recognize that a fully-coupled explosion of 1 kt in salt in high-Q low attenuation areas of the Former Soviet Union FSU, like Azgir, has an mb of 4.4 fully decoupled events of 1 and 10 kt have mbs of about 2.6 and 3.4. Most areas of thick salt deposits in the C.I.S. are typified by high Q for P waves and low natural seismic activity. Yields of all known nuclear explosions at Azgir and in other areas of thick salt deposits in the C. I.S. through May 1993 are recalculated. The yields of fully decoupled nuclear explosions of Y or 0.5 kt that possibly could be detonated in the cavities produced by those events are calculated.

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  • Nuclear Weapons

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