Silencing the Bomb Page 10

  I flew to Las Vegas on the day of the explosion and drove a rental car about 100 miles (160 km) to the town of Alamo, where Molnar and Jacob were staying. Halfway to Alamo, snow started to fall heavily, a weather condition that was supposed to be ruled out when deciding to fire such a large explosion. Those responsible at the test site probably wanted to complete the Benham test before the upcoming holidays. Fortunately, Benham did not vent—that is, leak radioactive materials into the atmosphere.

  In a 1969 paper, Molnar, Jacob, and I found no significant change in the numbers of small earthquakes within 15 miles (25 km) of each instrument from before to after Benham. The explosion triggered numerous very small aftershocks, but they were confined to within about 6 miles (10 km) of its epicenter.

  In late December 1968, after monitoring Benham, Jacob and I decided to move the portable Lamont instruments to Death Valley, California, just west of the Nevada border, to monitor several active faults. Molnar returned to Lamont. Our van was having mechanical problems, so we decided to stop midway for repairs in Las Vegas.

  Because the number of working daylight hours was short in late December, we typically got up well before daylight for breakfast and ate dinner after dark. We went to a casino in Las Vegas near our motel for breakfast the next morning about 5 AM. TV sets had been set up so that patrons could see the splashdown in the Pacific of the Apollo flight that first flew around the moon but did not land on it. We were happy to see the successful landing while having breakfast, but most gamblers were oblivious to the exciting scenes on the TVs.

  After we set up our instruments in Death Valley later that day, it was too cold to sleep in the van, so we drove back uphill to a motel in tiny Death Valley Junction, the same route on which mule teams hauled borax to trains at the Junction. Those trains and the mule teams had long disappeared. The next morning, December 31, at 5 AM, we went for breakfast at the only diner in town. A man came over to our table and remarked that we must not be from around there and was delighted to hear we were from New York. He told us that his wife, Marta Becket, would be dancing a ballet that evening, New Year’s Eve, in town at the Amargosa Opera House and invited us to join him for the performance. It proved to be a memorable evening. The year before, as Marta and her husband were on their way from Los Angeles to Las Vegas, they passed a recreation hall in town. She decided to rent it, renaming it Amargosa, its original name.

  Klaus indicated that he would be ten minutes or so late for the performance because he wanted to call his sister in Massachusetts to wish her Happy New Year. Becket’s husband said, “No problem; we’ll wait for you to start.” We turned out to be the only people who stayed for the full performance. One family came late and left early. Becket’s husband pulled the curtain, worked the lights, and played recorded music. On the back wall of the small theater, he and Marta had painted a copy of Velasquez’s Las Meninas, in which the young infanta Margaret Theresa is surrounded by her entourage of maids of honor, a chaperone, a bodyguard, two dwarfs, and a dog. They said they went ahead with ballet performances even if no one else came; they had Las Meninas for spectators. The Opera House, now on the National Register of Historic Places, was discovered several years later and became successful. Marta’s final show was in 2012.

  Afterward, Klaus and I were invited to have a glass of champagne with Marta and her husband. About an hour before midnight, as we stood around celebrating, a frightened woman’s face appeared at a window of their home. She said her husband, who was to get out of prison at midnight, had vowed to kill a man, and she needed help in finding him. As Ms. Becket’s husband was about to join her, Marta implored him not to go, but he said, “These are our neighbors, and I need to help them.” So off he went. We headed back to our motel room and slept soundly as the New Year arrived.

  8

  PEACEFUL NUCLEAR EXPLOSIONS

  During the Moscow negotiations for the Threshold Test Ban Treaty (TTBT) in 1974, the Soviet delegation insisted on two major conditions. One condition, as mentioned earlier and discussed in more detail in later chapters, was that the threshold be based on yield, not seismic magnitude. A second was that the treaty be limited to the testing of nuclear weapons underground and not apply to peaceful nuclear explosions (PNEs). The United States accepted both conditions, and the two parties signed the TTBT in July 1974. Soon after, negotiations were started on a separate bilateral treaty dealing with peaceful nuclear explosions; it was signed two years later in 1976.

  The United States and the Soviet Union used peaceful explosions to create large underground cavities in salt for storage of various products, to break rock for petroleum recovery, and as large sources of energy for seismological studies of the Earth’s crust and upper mantle. The numerous cavities created in salt by peaceful explosions have been of great concern because some could be used for evasive (muffled) nuclear testing. One large cavity at Azgir in western Kazakhstan was, in fact, used by the Soviets for a partially decoupled test. It was the largest evasive test ever conducted.

  In 1974 the Soviet delegation stated that their country needed to conduct numerous peaceful explosions to benefit its national economy. A major problem, however, is that a peaceful explosion cannot be distinguished from a weapon test by either seismic means or satellite imagery. For example, India claimed that its first nuclear test in 1974, which produced seismic waves like those from a weapon test, was a peaceful nuclear explosion. Years later it became clear that it actually was part of India’s development of nuclear weapons. From this, the United States concluded that peaceful nuclear explosions needed to be subject to a treaty that would spell out what was acceptable.

  Distinguishing weapons tests from peaceful nuclear explosions ultimately was resolved in the Peaceful Nuclear Explosions Treaty (PNET) of 1976. It stated that any nuclear explosion at the declared weapons test sites of the two countries would be considered a weapons test and would be subject to the terms of the TTBT of 1974. All nuclear explosions outside of the declared nuclear weapons test sites would be considered to be peaceful explosions and would be covered by the terms of the PNET.

  THE U.S. PNE PROGRAM

  The United States began peaceful nuclear explosions in 1957 in a program called Plowshare, which ended in 1973, a year before the Threshold Treaty was signed. Plowshare’s two main purposes were excavating harbors and stimulating the flow of petroleum. In the 1950s and 1960s, many people in the United States, especially in the Atomic Energy Commission and the weapons laboratories, thought that PNEs could be utilized to accomplish many unique and important purposes. Others believed they were simply an excuse for continued nuclear testing.

  Donald Springer of Livermore and others published a list of twenty-three peaceful nuclear explosive devices that were tested at the Nevada Test Site (NTS) from 1962 through 1971. Yields of all of these U.S. tests were declassified. One of the largest was the 104-kiloton Sedan explosion in 1962. That PNE excavated a huge hole with a diameter of 1280 feet (390 meters)—the length of more than three American football fields—and a depth of 320 feet (98 meters). The purpose of Sedan was to demonstrate that large holes could be created in the ground for various purposes using PNEs. Satellite imagery easily detected the crater it formed.

  Some U.S. proponents advocated using very large nuclear explosions to create harbors in Alaska and Australia as well as megaton-size explosions to create a sea level Panama Canal during the time the United States controlled the Canal Zone. Fortunately, the United States did not go ahead with any of those projects because immense amounts of fallout would have resulted from those huge explosions. It is not difficult to imagine the great international political storm that would have occurred if that project in Panama had gone forward.

  The United States conducted the Gnome explosion in salt in southeastern New Mexico in 1961. Gnome and the 1964 explosion Salmon in Mississippi, which was not a PNE, left underground cavities standing long afterward. Most cavities in materials other than salt collapse within seconds to days. The Soviet Union use
d nuclear explosions to create many cavities in salt for the storage of gas, oil, and waste products.

  The United States conducted a number of nuclear explosions to obtain gas that was not accessible by standard drilling methods in tightly locked pores of very fine-grained rock. Gasbuggy of 29 kilotons was detonated in New Mexico in 1967, and 40-kiloton Rulison in western Colorado in 1969. Rio Blanco, set off in northwestern Colorado in 1973, consisted of three 33-kiloton explosions in a single hole but at different depths. Not very effective in stimulating gas, it was the last of the U.S. peaceful nuclear explosions.

  I visited the Rio Blanco site about a year or two after it was detonated as part of a field trip for a U.S.-Japan conference on earthquake prediction in Salt Lake City. The Department of Energy (DOE) showed us a film about the project that included small children bouncing on the devices prior to their being lowered down a hole in an effort to demonstrate how safe PNEs were. I found the demonstration especially objectionable because several of our Japanese colleagues had lived through World War II and the bombing of Hiroshima.

  There were several other objections to the use of PNEs to obtain gas. One was that the gas produced would be radioactive. Another was that a large amount of water would be needed in dry regions for further exploitation. Today, tight gas formations are being exploited in various parts of the eastern and central United States using hydrofracturing (fracking). Recent technology permits a horizontal well to be drilled from a vertical hole at depth into a tight geological formation such as shale. Fluids injected at high pressure along that horizontal hole create many vertical hydrofractures, which release trapped gas. The process is hotly debated today because it requires great amounts of water as well as the disposal of the toxic liquid wastes produced during fracking.

  SOVIET PNE PROGRAM

  The Soviet program of peaceful nuclear explosions (figure 8.1) started in 1965, later than in the United States, but it continued much longer, until 1988. The USSR conducted its first peaceful nuclear explosion of 125 kilotons at its Eastern Kazakhstan test site, where it formed a crater that is easily seen on unclassified satellite images. Yields of the explosion and some later PNEs were released by the Soviet Union at international conferences on peaceful explosions. D. D. Sultanov and others published locations, depths, times, names, and yields of 122 Soviet PNEs in 1999.

  FIGURE 8.1

  Sites of peaceful nuclear explosions in the Soviet Union.

  Source: Bulatov, 1993.

  During the 1974 negotiations for the TTBT, the Soviet delegation stated their country would like to use very large nuclear explosions to construct a major canal that would bring abundant water that normally flows into the Arctic Ocean through the Pechora River into the south-flowing Kama River, which empties into the water-starved Caspian Sea. A few nuclear explosions with yields up to about 100 kilotons were detonated along the line of the proposed canal in the early 1970s to test the concept.

  The bilateral Peaceful Nuclear Explosion Treaty (PNET) of 1976 permitted the Soviet Union to perform a series of nuclear explosions whose total yield was larger than the 150-kiloton limit of the TTBT provided the United States could conduct extensive on-site observations. Each explosion in the series was to be no larger than 150 kilotons. On the advice of his science adviser, however, Secretary-General Gorbachev later canceled the Pechora-Kama project on the grounds that the proposed nuclear explosives would create dangerous radioactive fallout. After the PNET was signed in 1976, Russia did not detonate peaceful nuclear explosions nearly as large as 150 kilotons.

  Soviet explosions in salt are important because the deep cavities that remain after those events could be used at some point to conduct decoupled or muffled nuclear tests. I made a major finding in 1996, discovering that none of the cavities created by the Soviets, with the exception of those at Azgir in western Kazakhstan, was large enough to be used to conduct a fully decoupled nuclear explosion with a yield larger than one kiloton.

  It is important to note that Kazakhstan became a separate nation following the dissolution of the Soviet Union in 1991. The ninth largest country in the world in area, bigger than Western Europe, Kazakhstan has not detonated any nuclear weapons since its independence. It is very antinuclear as a result of fallout from past nuclear tests. Kazakhstan has ratified both the Nonproliferation Treaty and the Comprehensive Nuclear Test Ban Treaty.

  Cavities created in salt by well-coupled nuclear explosions are only suitable for conducting fully decoupled nuclear explosions of much smaller yield, up to 5 percent as large as that of the explosion that created the cavity. Therefore, because of the limited size of cavities created in salt by past well-coupled nuclear explosions in the Russian Republic, they would be suitable for fully decoupled tests only of sub-kiloton size.

  The locations of past nuclear explosions in salt in Russia and Kazakhstan are known very accurately. In addition, earthquakes in and near salt deposits are very few, so they can be recognized readily. Explosions in salt also are relatively easy to detect because salt transmits seismic waves as easily as hard rocks. Therefore, monitoring sites of previous nuclear explosions in salt in the Russian Republic is relatively easy.

  NUCLEAR EXPLOSIONS IN SALT AT AZGIR

  In 1966 the Soviet Union conducted a PNE of 1.1 kilotons in salt to the north of the Caspian Sea near the small town of Azgir, Kazakhstan. It formed a collapsed crater at the surface because the explosion was of quite shallow depth. The crater is visible on unclassified images made by the French SPOT satellite. In 1996 I made a special study of it, searching all available records from the worldwide seismic station network and Canadian stations for P waves from the event. Using sixteen stations, I obtained an average mb of 4.5, a sizable magnitude for an event whose yield was only 1.1 kiloton. The ability to detect such a small event using data mainly from simple unclassified stations outside the Soviet Union reflects the efficient transmission of energy from underground explosions in salt at Azgir. Remember from earlier chapters that the seismic magnitudes of underground explosions at the Nevada Test Site with yields of about one kiloton were much smaller than mb 4.5.

  I obtained similar results for fourteen larger nuclear explosions in salt at Azgir between 1968 and 1979. Situated in a remote area, Azgir appears to have been a testing area for using nuclear explosions either to form cavities in salt or to conduct nuclear explosions within two of those cavities. Azgir is situated in the Pre-Caspian depression, which contains the largest concentration of salt domes in the world.

  The Soviets detonated a second peaceful nuclear explosion north of Azgir in 1968. Its yield was reported as 25 to 27 kilotons. Soviet workers stated that its cavity filled with water after the 1968 shot. They used the cavity to set off six additional very small nuclear explosions with yields ranging from 0.01 to 0.5 kilotons (10 to 500 tons). The sensitive NORSAR seismic array in southern Norway recorded the four smallest events. Data from the two largest explosions in the cavity during 1975 and 1979 aided them in analyzing the smaller events. Their occurrence on nearly an exact hour early in the morning helped in their identification. Detecting the smallest nuclear explosion in that cavity with a yield of about 10 tons and a magnitude of 2.8 was a significant accomplishment. They would be even more easily detected today.

  Soviet scientists stated that the small explosions in the water-filled cavity were intended to test their use for deep seismic sounding of the crust and upper mantle at large distances across their country. They were very well coupled explosions, not decoupled or muffled, because they were fired in water, making them valuable studies of the crust and mantle. Soviet scientists reported that one of those small explosions was used to generate elements beyond uranium in the periodic table.

  The Soviet Union went on to conduct many nuclear and chemical explosions to explore its deep Earth structure along lines that extended thousands of miles (kilometers) (Figure 8.1). It probably used more PNEs for this purpose than for any other task. The seismic signals from PNEs of about 10 kilotons could be observe
d at those large distances, permitting Earth structures to be imaged as deep as 200 kilometers. Conducting such a large number of very large chemical explosions would have been more difficult.

  Eight large underground nuclear explosions were conducted to the northeast of the small town of Azgir from 1971 to 1979. Those sites, along with numerous roads leading to them, were visible on unclassified SPOT satellite images taken in 1988.

  The cavity created by the nuclear explosion of 64 kilotons in 1971 was used to conduct a partially decoupled nuclear explosion of 8 to 10 kilotons on March 26, 1976. It is the only known nuclear explosion that was significantly decoupled or muffled with a yield larger than that of the U.S. Sterling explosion of 0.38 kilotons.

  OTHER SOVIET NUCLEAR EXPLOSIONS IN SALT

  Sultanov and others reported that fifteen cavities were formed by PNEs with yields of about 3 to 8.5 kilotons from 1980 to 1984 at depths of 3000 to 3600 feet (900 to 1100 m) at Astrakhan near the mouth of the Volga River in the Russian Republic. All were intended for the storage of propane and butane within a large gas field. In 2001 William Leith of the U.S. Geological Survey wrote to me that most, and perhaps all, of those cavities had completely collapsed within several years of the explosions that created them. Those cavities were not used and remained air filled for years. That, coupled with the fact that salt at the depths of the Astrakhan explosions likely is not homogeneous and probably contains layers of other sedimentary rocks, contributed to the collapses.