Word: seismic
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Dates: during 1950-1959
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...deep underground explosion sends no air waves, but such explosions, and surface explosions too, send seismic waves through the earth. A station in a quiet place can detect the waves from a one-kiloton explosion as much as 2,200 miles away. The detecting apparatus is accurate enough to pinpoint the explosion within an area of 40-80 sq. mi., less than one-quarter the area of New York City...
Each of these methods, the East-West experts pointed out, has its faults. Acoustic waves from a volcanic eruption, for instance, can be mistaken for waves from a nuclear test. Seismic waves from earthquakes can be misinterpreted, too. Nuclear tests deep under the earth or ocean yield no radioactive fallout, send out no air waves or radio waves. But they do send waves through the ocean, the earth, or both. Each type of test is detectable by one or more methods...
...space. ¶ Electromagnetic radiation. Control posts, equipped with photocells and low-frequency radio receivers could pick up the X rays and ultraviolet rays that turn into light and radio waves after an explosion. They could even pick up the light pulses resulting from a blast in space. ¶ The seismic method, which with astonishing accuracy has already detected the size and location of underground explosions thousands of miles away. Main drawback: seismographs cannot always distinguish between a nuclear blast and an earthquake, though differences between them are now being studied...
...grip of an Ice Age, with icecaps at both polar regions, and the IGY wants to know whether it is coming or going. In Greenland, scientists have bored 1,438 ft. into the ice. In Antarctica they are doing the same, and measuring the great icecap by seismic waves. Other scientists are observing the advance or retreat of smaller glaciers in Temperate Zone mountains. Their reports may tell what changes of climate lie in the earth's future...
...Bullen expressed gratitude. There would not be time, he said, to set up special apparatus in remote places, but the world's 600-odd established seismic stations will be listening. The waves from Nevada will surely be recorded all over the earth...