Silencing the Bomb Read online

  Again, the agenda was set and tightly controlled. I was given about five minutes to counter Romney’s claims and to mention the findings of the previous AFTAC panel. Helmberger was not helpful in stating that the magnitude bias between Nevada and Eastern Kazakhstan likely was small. Simmons unfortunately accepted Romney’s assertions because he regarded him as an expert who worked full-time on seismic verification.

  Romney, I discovered with time, was a very cagey person who knew his audience very well, including what he could get away with. He would give one story to a knowledgeable seismologist and another to people, like the others on this ad hoc panel, who were not familiar with what had gone on at the last AFTAC panel or what Marshall and Springer had concluded in 1976. I found Romney’s presentation to the ad hoc panel outrageously deceptive. I never trusted him again. I think he likely regarded me as an enemy for my views on this panel and the AFTAC one that preceded it.

  Romney persuaded the ad hoc group to endorse a one-page secret document stating that the Russians could be breaking the treaty by testing weapons with yields much larger than the 150-kiloton limit of the TTBT. How much greater is likely still classified. I came away very dejected with that outcome and angry about Romney’s manipulation of the panel. That classified document “rang a lot of bells” in the U.S. government. At the time that yields of tests at Eastern Kazakhstan were being overestimated by many times, Romney concluded that the actual yields were even higher, not smaller.

  REVIEW BY CARTER’S SCIENCE ADVISER

  In 1977 Jimmy Carter was inaugurated as president, and seismologist Frank Press became his science adviser and head of the Office of Science and Technology Policy. I wrote an unclassified letter to Frank, whom I had known for a long time, saying I had been part of the AFTAC panel and the recent ad hoc committee. I stated that I strongly disagreed with the one-page statement of the ad hoc committee and that this was a very important matter. Press soon wrote back requesting that I send him the secret document and my views about it via a classified route. I complied and sent Press a classified letter of a few pages describing why I disagreed and why I thought that the ad hoc panel’s conclusions were quite incorrect.

  Press convened a panel of his own, in the West Wing of the White House on September 1 and 2, 1977, to explore again the evidence about yields of Soviet explosions. He called Romney to testify. The panel consisted of Springer from Livermore, seismologist Robert Massé of AFTAC, and me. Massé broke ranks with the AFTAC-ARPA view and said that Romney was incorrect about determining yields of Soviet tests. Springer, a very straightforward person, said in a nonacrimonious way that Romney was wrong. I voiced similar views. The panel concluded that the United States was overestimating the yields of Soviet explosions.

  The panel recommended that the official classified magnitude-yield formula should be changed to include a correction for magnitude bias using P waves and that surface waves should be incorporated into yield determinations. It was my view that AFTAC needed to do more work on how to merge P-wave and surface-wave data in a thoughtful way. One way was to use Soviet explosions characterized by low to little tectonic release to obtain a better estimate of mb bias. AFTAC and the Defense Department, however, did not permit that work to go forward, stating they needed to be “tasked” to do it.

  I was told that Frank Press forwarded our recommendation about yield determination using both P and surface waves to Zbigniew Brzezinski, who headed the National Security Council under Carter, but that Brzezinski overruled Press and our recommendation, saying it was stupid to have two different methods for yield determination.

  I also learned that the Carter administration concluded that the United States should drill deeper holes in Nevada to test weapons exceeding the 150-kiloton limit of the TTBT. This was in answer to the Soviets’ alleged cheating on the treaty. I would like to think that my and a few others’ raising hell and enough valid scientific points helped forestall the United States from setting off explosions above the limit of the Threshold Treaty. That would have stirred up a hornet’s nest in Russia at a time of tense relations between our two countries.

  MORE EVIDENCE OF BIAS IN ESTIMATING SOVIET YIELDS

  By 1979 it was clear from a long and thorough publication of Marshall, Springer, and Rodean that the magnitude (mb) bias for explosions in hard rock between the Nevada Test Site and Eastern Kazakhstan was 0.3 to 0.4 magnitude units. Their work also found that the propagation of P waves from the French test site in southern Algeria and Nevada were very similar. Romney had claimed that the Algerian site in the Hoggar (Ahaggar) region was situated in old rocks of the West African Shield and hence could be used to calibrate Soviet yields. Instead, Hoggar is one of several young elevated regions in Africa that are known as “hot spots” to those familiar with plate tectonics. It is not an old geological area like the surrounding West African Shield.

  Marshall and others found that the Pn velocity beneath Hoggar itself was low, as it was beneath Nevada. Therefore, P waves were absorbed beneath Hoggar in a similar way to those beneath Nevada. Thus, Hoggar data also needed to have a correction made for a bias of about 0.3 to 0.4 magnitude units. The bottom line was that it was not a good analog for Eastern Kazakhstan.

  Clearly, the British government was concerned about the U.S. methodology for determining yields of Soviet tests. Otherwise, Marshall, who worked for the UK Ministry of Defense on seismology, would not have stated his views so forthrightly in peer-reviewed journals. The same is true for Springer and Rodean—two knowledgeable scientists who had long worked at Livermore. It is quite surprising, as well as unfortunate, that their views did not carry more weight in the U.S. debate about Soviet yields. That debate festered until 1988.

  A FAILED ATTEMPT AT A FULL TEST BAN TREATY

  After 1963, a full test ban (a CTBT) did not resurface until the Carter administration entered into negotiations with the Soviet Union and Britain in 1977. The United States decided not to press for ratification of the TTBT and PNET but to push instead for a full ban on nuclear testing. Formal negotiations started in Geneva in July 1977. In his 1981 book, Glen Seaborg indicates that Herbert York, who led the U.S. negotiations from 1979 to 1980, informed him about what had been accomplished, most of it by the end of 1978. The main outlines of a treaty included automatic seismic detection stations on the territories of the three parties, a system of voluntary on-site inspections with arrangements for challenges and responses, a treaty with a three-year duration, and a moratorium on peaceful nuclear explosions.

  After an initial good start, the CTBT negotiations stalemated when Margaret Thatcher became the UK prime minister, opposition to a CTBT increased in the United States, the Soviet Union was reluctant to accept on-site inspections, and the Soviets invaded Afghanistan. Opponents of a CTBT in the United States cited the need to test weapons for the Trident II missile and energy-directed weapons (called “Star Wars” by opponents). In addition, the Carter administration did not want to push for a CTBT until the Strategic Arms Limitation Treaty, SALT II, was completed.

  10

  CONTINUED DEBATE ABOUT YIELDS, ACCUSATIONS OF SOVIET CHEATING ON THE THRESHOLD TREATY, AND ITS ENTRY INTO FORCE

  This chapter covers the continuing long debate in the 1980s about determining the yields of Soviet nuclear explosions. During the Reagan and first Bush administrations, the U.S. government charged that the Soviet Union had cheated on the Threshold Test Ban Treaty (TTBT) by testing nuclear weapons above its 150-kiloton limit. The issue of yield determination was finally resolved in 1988 by close-in monitoring of explosions by the United States and the USSR at the other’s test sites. The United States and Russia ratified an amended TTBT, which entered into force in December 1990.

  My article “The Verification of a Comprehensive Nuclear Test Ban” with Jack Evernden in the Scientific American of October 1982 drew criticism from DARPA officials for its conclusions about the yields of Soviet explosions, our finding that the Soviet Union had not cheated on the Threshold Treaty, and our claim
s that a full test ban could be monitored effectively. In the early 1980s, the Nuclear Monitoring Research Office of DARPA included Ralph Alewine, Thomas Bache, Carl Romney, and Alan Ryall, all of whom opposed a full test ban. All very conservative in their views on national security policies, they focused almost entirely on the determination of Soviet yields.

  Bache wrote a DARPA report on yield determination in 1982 that stated, for yield estimation with short-period P waves, an important issue is possible bias caused by path effects (my italics). By path effects he meant differences in the absorption (attenuation) of P waves for paths from Soviet explosions in Eastern Kazakhstan compared to those from the Nevada Test Site. When expressed in terms of seismic magnitude, those differences are called magnitude or mb bias, as discussed in the previous chapter.

  Bias is a systematic difference, like measuring a length without realizing that an inch has been cut off the measuring stick. Just making additional P-wave measurements of magnitude (akin to measurements of length using a defective ruler) does not decrease the bias. When an average mb is obtained from about a hundred stations, the uncertainty is very small, about 0.04 mb units. To obtain an accurate estimate of the yield of a Soviet explosion from an average value of mb, however, that magnitude still needs to be corrected for bias between it and underground explosions in Nevada. The systematic difference of about 0.3 to 0.4 mb units between those sites dominates the uncertainty in yield determination for Soviet tests. Hence, the main task is to determine that systematic error, not to focus on more or better mb measurements.

  Bache also stated, “Regionally varying attenuation [absorption of P waves] is an important potential cause for bias in yield estimates [my italics]. Current knowledge suggests that differences of 0.3 or 0.4 mb for otherwise identical events in different areas can be expected, but it is difficult to demonstrate that they actually occur.”

  In April 1983, Larry Burdick, a seismologist at Woodward-Clyde Consultants, wrote to me stating that Bache, his contract monitor, had reviewed Burdick’s report on magnitude bias and said to him, “Your section 2 is a good example of the problems (futility?) associated with estimating a specific site amplitude bias from travel time residuals. Some important people seem to think otherwise. For example note the way Sykes and Evernden use travel time residuals to estimate mb bias of Semipalatinsk [Eastern Kazakhstan] compared to NTS on page 55 of their article in the October Scientific American. I would appreciate your sending a note to Sykes drawing attention to this section in your report.” Burdick then wrote to me, “Since we ultimately use travel times to estimate site bias, we obviously believe that this is a valid approach. I infer that Tom [Bache] believes otherwise.” Since I had read Burdick’s report, Bache was at the very least not very professional in asking Burdick to send me a note citing the errors of our ways.

  In 1982 the Reagan administration decided not to submit either the TTBT or its companion Peaceful Nuclear Explosion Treaty (PNET) for ratification by the U.S. Senate until the USSR agreed to additional verification measures. Two years later, in 1984, the administration publicly charged the Soviet Union with a probable violation of the TTBT. This was part of a larger set of accusations that the USSR most likely had cheated on other arms control agreements, including the Anti-Ballistic Missile (ABM) Treaty, encryption of data during missile testing, the number of new missile systems permitted under the second Strategic Arms Limitation Treaty, and the Chemical Weapons Treaty.

  Evernden and I had concluded, however, that reports of Soviet cheating on the Threshold Treaty were erroneous. When our calibration was used, it was apparent that none of the Russian weapons tests exceeded the 150-kiloton limit of the TTBT. Several Soviet explosions did come close to that limit, however, as was also the case for some U.S. tests in Nevada.

  SYMPOSIUM IN 1983 ON THE VERIFICATION OF TEST BAN TREATIES

  Evernden and I organized a symposium for the American Geophysical Union (AGU) on Verification of Nuclear Test Ban Treaties. This symposium, held in Baltimore in June 1983, was intended (1) to present arguments for and against verification of a complete test ban, (2) to assess the determination of yields under the Threshold Treaty, and (3) to address accusations that the Soviet Union had cheated on the TTBT.

  About five hundred people attended, including many from U.S. federal agencies. A morning session was devoted to the Threshold Treaty, while the afternoon dealt with monitoring a full nuclear test ban (a CTBT). We invited Bache and Alewine of DARPA to give talks on each, which they did. Of course, Evernden and I knew to expect strong criticisms from them. I obtained a written copy of their unpublished eleven-page presentation, plus nineteen figures, titled “Monitoring a Comprehensive Test Ban Treaty.”

  The worst was yet to come from DARPA: an accusation that someone or some agency had leaked the purported revised U.S. classified methodology for determining yields of Soviet explosions to the media. Figure 10.1, from their presentation, showed P-wave magnitudes, mb, of nuclear explosions in Eastern Kazakhstan from the start of the TTBT on April 1, 1976, through 1982. The dates in figure 10.2, from our paper, included that period and extended it back to 1970.

  FIGURE 10.1

  Seismic magnitudes mb (filled circles) as a function of date for underground nuclear explosions at the Soviet test site in Eastern Kazakhstan.

  Source: 1983 presentation by Bache and Alewine of the U.S. Department of Defense, published in Pike and Rich, 1984.

  FIGURE 10.2

  Seismic magnitudes mb for underground nuclear explosions at Eastern Kazakhstan.

  Source: Sykes, Evernden, and Cifuentes, 1983; also published in Pike and Rich, 1984.

  The DARPA chart in figure 10.1 was annotated to show 150 kilotons for explosions in Nevada and interpretations of mb values associated with explosions of that yield in Eastern Kazakhstan—pre and post July 1977. It indicated that Soviet tests seemed to double in yield between 1978 and 1979 and claimed this was evidence that the Soviets had discovered U.S. plans to modify its classified yield calibration formula, presumably about July 1977. According to Alewine and Bache, the USSR raised the yields of their tests accordingly. The dotted horizontal line in figure 10.1 indicates (mistakenly) that fourteen Soviet tests after 1978 exceeded the 150-kiloton limit of the TTBT, four of them by a factor of two. Bache and colleagues published a similar figure and arguments again in 1986.

  Figure 10.2, which I presented at the 1983 symposium, shows that magnitudes and yields of Soviet tests actually rose gradually over a period of three years and then stabilized at a magnitude mb close to 6.2. Evernden, Cifuentes, and I associated mb 6.2 with a yield of about 150 kilotons, factoring in an mb bias of 0.35 units between hard rock in Eastern Kazakhstan and Nevada.

  Figure 10.1 indicates a magnitude of 5.65 for explosions of 150 kilotons in Nevada, but this magnitude is appropriate only for tests in softer rocks, not the much harder rocks in Eastern Kazakhstan. Without taking into account the magnitude bias between the two test sites and the difference in rock types, the inference from the Department of Defense work was that Soviet tests of magnitude 6.2 corresponded to yields of about 600 to 800 kilotons. Evernden and I thought Alewine and Bache were not only incorrect but misleading as well.

  After each talk at the 1983 symposium, we devoted about five minutes to questions for the speakers. Alewine received several, including one from me: “Then I have one final question that is to do with the last sentence in your abstract. And there, perhaps to paraphrase you, you liken [sic] yields of 600 to 800 kilotons or larger, and none of the yields you were talking about here [in your oral presentation] are in that range. Could you discuss that?” Alewine replied, “I didn’t have that in the paper.” I replied, “It’s in your [printed] abstract.” Alewine: “Right. Well, what we observed, I think what we said in the paper is that for an mb 6.2 in the U.S. experience, we have not seen an mb 6.2 unless yields were in the 600/800 kiloton range.” Evernden responded, “But that means that the feeling that numerous people got out of the abstract, that you were con
cluding that possibly the Soviets had tested to 600/800 kilotons, was a false interpretation of your abstract. Is that right?” Alewine: “That’s right.”

  In addition, I recalculated magnitudes to three significant figures (6.21, 6.14, etc.) for figure 10.2. It is clear in Department of Defense figure 10.1, however, that the DARPA scientists calculated magnitudes to only two significant figures (6.2, 6.1, etc.). Rounding off magnitudes to two significant figures is sufficient for arguing about a factor of two but not in deciding if a yield was, say, 140, 150, or 160 kilotons.

  Table 10.1 lists several quotations from media coverage in 1982 and 1983 claiming that the yields of several Soviet explosions exceeded the 150-kiloton limit of the Threshold Treaty by large amounts. Some of these probably involved leaks to conservative columnists.

  TABLE 10.1 Published statements about yields of the largest USSR explosions under the Threshold Test Ban Treaty

  JACK ANDERSON—COLUMN IN WASHINGTON POST, AUGUST 1982

  350 kt “…the Soviets appear to have exceeded the 150-kiloton limit at least 11 times since 1978. One test in September 1980 was clocked at a likely size of 350 kilotons, according to my sources.”

  260 kt “As recently as July 4, the Soviets set off a huge nuclear blast. It was estimated at a likely 260 kilotons,…”

  HAROLD M. AGNEW—LETTER TO SCIENCE, APRIL 8, 1983

  400 kt “…subsequent tests appeared to us to range as high as 400 kilotons…”

  ALEWINE AND BACHE—EOS, MAY 1983 (ABSTRACT FOR SYMPOSIUM ON JUNE 2)