Frustration turned to delight Friday as American and Soviet scientists declared success in the first of a series of experiments they hope will prove that a cheat-proof ban on nuclear weapons testing is possible.
Scores of seismic monitors from both countries were set up to record the vibrations from three non-nuclear explosions scheduled in remote areas of Nevada on Friday and Saturday to see if even the smallest blasts could be detected.Friday's first detonation of 10 tons of TNT buried 160 feet below the Black Rock Desert 100 miles north of Reno did not appear to register on any of the seismometers initially, but it later was detected on sensitive Soviet equipment 250 miles away, said Paul Allen of the Natural Resources Defense Council.
After a more detailed study, Allen said, the explosion was found to have registered on the seismometers close to the blast site as well.
He said the Soviet unit in Deep Springs, Calif., recorded the blast 100 seconds after it was detonated in the desert, sharply jolting the ground under observers 500 feet away.
Holly Eissler, research geophysicist at the University of California San Diego, said scientists had been concerned that Nevada's complex geography would not carry sound waves to monitoring stations 250-430 miles off.
A second 10-ton blast was scheduled late Friday at Lathrop Wells, 50 miles south of the Nevada Test Site, where all U.S. nuclear weapons are tested. A 15-ton charge was to be detonated Saturday at Broken Hills, 100 miles east of Carson City.
If the experiments succeed, they would show that "any chances for cheating are about excluded" under a test ban, Evgeni Velikhov, vice president of the Soviet Academy of Sciences and an observer of the test said.
"We think the comprehensive test ban is very important," said Velikhov, an adviser to Soviet leader Mikhail Gorbachev. "It is extremely important to stop the arms race."
The experiment is part of a unique agreement between the Soviet Academy of Sciences and the privately funded Natural Resources Defense Council of the United States.
The blasts were to be monitored from three permanent centers surrounding the Nevada Test Site, including one at Deep Springs, Calif., 25 miles east of Bishop, Calif., where the Soviet technicians installed a ton of their own instruments for their first use in this country.
"Typical underground nuclear explosions are measured in hundreds or thousands of tons of TNT," Thomas Cochran, senior staff scientist of the Natural Resources Defense Council, said at a news conference. "By detonating only 10 to 15 tons, we will show that it is possible to detect very small explosions."
By comparison, the House passed a bill Thursday that calls for a ban on all underground nuclear explosions equivalent to more than 1,000 tons of TNT, if the Soviet Union agreed to do the same.
One objection to a test ban has been that low-yield blasts could be virtually undetectable, particularly if they were muffled in deep caverns.
The equipment used in the weekend tests was designed to be sophisticated enough "to feel the difference between nuclear and industrial explosions and ... very small earthquakes," Cochran said.
The tests were expected to produce shock waves equivalent to earthquakes measuring 1 or 2 on the Richter scale of ground motion, said Keith Priestley of the University of Nevada-Reno seismology laboratory.
In addition to the equipment from the Soviet Academy of Sciences and the Natural Resources Defense Center, the University of Nevada-Reno and the University of Wisconsin arranged to take readings at 23 sites. And the U.S. Geological Survey installed 120 seismometers and recorders along a line from Nevada's northwestern corner to its southern tip 450 miles away.