As public sensitivity to radiation increased, the weapons laboratories pursued efforts to reduce fallout by using lower yields, by applying reduced fission yield technology, and by containing explosions underground. The first experiment to contain an explosion completely underground was the "Rainier"test, which was detonated at the end of a spiraling tunnel in Rainier Mesa, Nevada, on September 19, 1957.2 A nuclear device with a known yield of 1.7 kilotons was selected for Rainier. The test was designed with two objectives: 1) to prevent the release of radioactivity, and 2) to determine whether diagnostic information could be obtained from an underground test. But Rainier had an additional result - it marked the entry of seismology as a major player in nuclear monitoring.
Although RAINIER produced strong seismic signals, the signals looked surprisingly like those of a normal earthquake. Thus, seismology held the promise of remote test monitoring, but it was obvious that the state of scientific understanding of seismology was inadequate. In 1959, the Special Assistant to the President for Science and Technology, Dr. Killian, formed the Panel on Seismic Improvement (now known as the Berkner Panel). This panel recommended a major, two-pronged program in seismology which came to be known as the VELA UNIFORM program. First, state-of-the-art seismic instrumentation needed to be developed and deployed globally. Second, there needed to be a major research program to improve understanding of the generation of seismic waves from nuclear explosions and the propagation of these waves through the Earth.
The parallel development of instrumentation and research proved extraordinarily successful, and progress in underground test monitoring was rapid. The World-Wide Standard Seismological Network (WWSSN) deployed 125 stations in 31 countries. For the first time, a global network provided seismologists the ability to study seismic events which were recorded on instruments with common, known characteristics. The WWSSN not only provided invaluable data for nuclear explosions, but it also provided seismologists with a tool to study natural seismicity i.e., earthquake activity. Much of the geophysical framework for plate tectonics is based on data collected from the WWSSN.
The research program developed a lasting partnership between the university community and government agencies charged with negotiating and monitoring weapons treaties. This partnership has resulted in a strong technology base, and has trained a generation of seismologists. It is fair to say that nearly every important development in earthquake seismology has been rooted, at least partially, in the VELA program. The box on the following page gives an abbreviated chronological listing of seismological research that has contributed to the VELA program. Thousands of papers published in peer-reviewed journals were authored by university seismologists funded by the VELA program.
Today, the challenges to the seismological community in monitoring a CTBT hold many analogies to the technical and research opportunities that emerged following the 1957 RAINIER explosion. This chapter will examine how the technical questions have evolved and how the research community can once again be involved in developing a solution to the monitoring problem through the application of existing knowledge, research, and instrumentation.
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Continue to:Chapter II, The New Challenge