Advances in detection devices and methods of analysis have allowed seismologists to identify virtually all events that might be nuclear explosions of possible military significance under the Comprehensive Test Ban Treaty (CTBT), according to Prof. Lynn R. Sykes of Columbia Universitys Lamont-Doherty Earth Observatory. Writing in the 29 October issue of Eos, published by the American Geophysical Union, Sykes analyzes 72 questionable events since 1960.
Verification was a major issue in the U.S. Senate debate in 1999, in which American ratification of the treaty was defeated. Since 1995, the International CTBT Organization has detected many small seismic events and has determined that many were earthquakes or otherwise identifiable. Under the treaty, however, the international organization is not charged with identifying all seismic events and is, in fact, not permitted to declare an event a nuclear explosion. Unresolved cases and possible nuclear events are referred to national CTBT agencies, whose work is usually classified.
Therefore, says Sykes, we do not always know how well the difficult cases are resolved. Only 72 events have been flagged in the literature or by the media as questionable or difficult to identify, a small fraction of all events recorded over the past 42 years, demonstrating the great progress made in verification, says Sykes. By studying technical characteristics of the seismic signals, nearly all of the 72 events have been identified as nuclear explosions, chemical explosions, earthquakes, or mine collapses, he writes.
Harvey Leifert | AGU
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