Contact:	Faye Yates						Embargoed for release
		Lamont-Doherty Earth Observatory		2 P.M. EDT, Oct. 22, 1997
		(914) 365-8878				
		faye@ldeo.columbia.edu



Columbia Scientists, in Nature Article, Dispute Finding
That Aug. 16 Event Was Russian Nuclear Test


	Two seismologists at Columbia University's Lamont-Doherty Earth 
Observatory, writing in the British journal Nature, have concluded that a seismic 
event on Aug. 16 north of mainland Russia was an earthquake, not a nuclear test.
	Seismic monitoring stations detected the event, which appeared to be in the 
vicinity of Novaya Zemlya, an island that is the site of a Russian nuclear weapons 
testing facility.  Newspaper reports quoted government sources describing the 
event as having "explosive characteristics" and a Clinton Administration 
spokesman maintained that technical data could be interpreted to support either 
the hypothesis of an earthquake or a nuclear test.
	Had the event indeed been a nuclear explosion, it would mean the Russian 
government had violated the terms of the Comprehensive Test Ban Treaty (CTBT), 
an agreement laboriously negotiated over the last two decades by the United 
States, Russia and other nations that bans such testing.
	Analysis by the two Columbia researchers, Paul Richards and Won-Young 
Kim, seismologists who specialize in nuclear test verification, shows the seismic 
event was actually a small earthquake.  The research, published in the Oct. 23 
issue of Nature, demonstrates that scientists have excellent capability to monitor 
such events in the vicinity of Novaya Zemlya, they said.
	Other scientific views at odds with the U.S. government's interpretation of 
the Aug. 16 event have been reported in the Washington Post and the New York 
Times.  The Nature report is based on one of the first independent tests of a new
International Monitoring System (IMS) that is being developed to verify the CTBT.  
The system is a global network of sensitive instruments designed to detect the 
various physical and chemical fingerprints of nuclear weapons tests.
	Data from these instruments are to be analyzed by the treaty participants in 
order to determine compliance with the test ban.  Since nuclear explosions can 
produce signals that may look like an earthquake, scientists must learn to 
differentiate between the two, the scientists said.
	Dr. Richards, the Mellon Professor of Natural Sciences, saw the Aug. 16 
event as an opportunity to test the capabilities of data obtained both from IMS and 
non-IMS sources to monitor nuclear tests under the test ban treaty.  In the Nature 
article, he and Dr. Kim, associate research scientist, state:  "The ease of location 
and identification of the 16 August event, with a magnitude of about 3.5, 
demonstrates that the CTBT can be monitored near the Russian test site down to 
magnitude 3, and maybe even lower.  . . .  So the 16 August event indicates 
excellent capability to monitor the CTBT."  Seismologists use the Richter scale to 
measure the size of both explosions and earthquakes; a magnitude of 3.5 
corresponds to an explosive yield of about one-twentieth of a kiloton.
	The Columbia seismologists drew on several lines of evidence to verify that 
the event was not an explosion.  First, the scientists compared seismic recordings
 of the questioned event with the recordings of a known nuclear explosion set off by 
the former Soviet Union in 1990.  Drs. Richards and Kim noted differences in the 
delay between the first arriving seismic shocks (P-waves) and ones arriving later 
(S-waves).  The recordings, from a Finnish monitoring station west of Novaya 
Zemlya, showed that S-waves from the 1997 event took 8 seconds longer to reach 
the station than those from the 1990 nuclear test, indicating that the more recent 
event was in fact nearly 100 kilometers, or about 62 miles, east of the test site.
	Additional work by other seismologists located the epicenter some 50 
kilometers to the southeast of Novaya Zemlya, in a part of the Kara Sea nearly 400 
meters deep.  An explosion of this size located under water would produce a large 
acoustic signature that would be picked up by sensitive seafloor microphones 
maintained by the U.S. government.  No such acoustic signature was observed.
	Neither the large underwater drilling apparatus that would have been
necessary for such a test, nor any radioactivity, was observed.  Drs. Richards and
Kim further noted the presence of several aftershocks in the region, which would 
not be expected if the event had been a nuclear test.
	"Aftershocks are common for earthquakes, but would not be detectable at 
IMS stations after small nuclear explosions at Novaya Zemlya," Dr. Richards 
said.
	Drs. Richards and Kim also analyzed the seismic waves produced by the 
event and recorded by seismological monitoring stations scattered throughout 
Eurasia.  These data are collected by various U.S. government and international 
programs and are available to the scientific research community.  Analyzing the 
size of shock waves at high frequencies, the seismologists found that the ratios of 
P to S waves were consistent with ratios for known earthquakes with epicenters 
near Novaya Zemlya.  This technique, which has been carefully refined at 
Lamont-Doherty and elsewhere, provides the most definitive evidence that the 
Aug. 16 event does not have "explosive characteristics," the scientists said.
	The U.S. government needs to provide mechanisms that allow officials to 
draw on new research in their decision-making, the scientists said.
	"When the research community is able to demonstrate a good new method 
of discrimination, or the need for good communication to non-IMS stations with 
openly available data, the development must be assessed and operational 
procedures perhaps revised," Drs. Richards and Kim wrote in Nature, adding 
that the existence of more than 10,000 seismographic research stations across the 
globe should be able to provide supplementary data on any problem event.
	Despite the U.S. government's refusal to acknowledge a mistake, both that 
government and the IMS have the technology to discern earthquakes from 
nuclear explosions, the scientists said.  "Our capability to monitor the CTBT is 
magnificent.  We have all these discriminants upon which knowledgeable 
decisions can be based," Dr. Richards said.
	Lamont-Doherty Earth Observatory is a part of the Columbia Earth 
Institute, founded this year to promote wise stewardship of the Earth's resources.



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