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Political Seismology or Seismological
Politics: Natural Resources Defense
Council–USSR Experiments in Underground
Nuclear Test Verification
by Anna Amramina
INTRODUCTION
In the 1980s, the Institute of Physics of the Earth (IPE) in Moscow was challenged by the Soviet Academy of Sciences with an
ambitious task to become the Soviet representative in an
unprecedented joint project with the United States of America
in a defense-sensitive area. In 1986–1988, a series of experiments was held on two major nuclear test sites, in Nevada in
the United States and Semipalatinsk in Kazakhstan, to prove
the scientific possibility of verifying the exact location and
yield of underground nuclear explosions. The story hardly
sounds sensational; however, there are reasons to believe that
it stands out in the chain of events that led to the current Comprehensive Nuclear-Test-Ban Treaty (CTBT). This paper
marks the twenty-fifth anniversary of the exceptional example
of seismologists acting on the forefront of global politics.
The majority of available materials on this project exist
only as technical reports, protocols, and presentations. The
course of events was covered extensively from the U.S. point
of view by an American historian of science, K.-H. Barth.
His paper, as well as this article, argues that there are situations
in which the critical mass of scientific knowledge can overpower the political pressure on the international scale (Barth,
2006); moreover, in times of a global threat, scientists can accumulate enough influence to become a strategic force for
change. This paper attempts a glimpse of the international seismological research in nuclear arms control at the end of the
Cold War through the lens of joint Soviet–American experiments in underground nuclear testing verifications from the
historical rather than the geophysical point of view, and it
is aimed at honoring the experiments as one of the independent research initiatives put forward by scientists that influenced the decisions of top government officials.
POLITICAL BACKGROUND
The initiative was preceded by nearly 20 years of deadlock in
negotiations between the Union of the Soviet Socialist Repubdoi: 10.1785/0220140183
lics (USSR) and the United States about nuclear test bans, in
which the issue of verification became a stumbling block.
There had been suspicions and accusations on technical
grounds concerning verification difficulties from both sides
since the Geneva Conference of Experts of 1958. One of the
main issues in this argument concerned the intentional concealment of underground nuclear tests or their yield; and, until
the issue was resolved scientifically, there seemed to be no end
to this fight. The last attempt at seeking understanding in this
matter was the signing of the 1974 Treaty on the Limitation of
Underground Nuclear Weapon Tests, also known as the
Threshold Test Ban Treaty (TTBT). It established a nuclear
threshold by prohibiting tests with a yield exceeding 150 kt,
but it did not put a final stop to either underground tests or
the atmosphere of mistrust between two major acting forces in
Western politics, resources, and warfare. In the following decade the U.S. administration was reluctant to become proactive
in this matter, and Soviet actions toward further test bans were
self-serving (Morrison, 1987).
The negotiations came to a halt with the deployment of
Soviet troops in Afghanistan in 1979. In 1982 President
Reagan, following the policy of his predecessor, Jimmy Carter,
declined to resume talks on a comprehensive test ban under the
pretexts of the demand for further nuclear testing, absence of
reliable methods of verification, and continuous violations of
the 150 kt threshold by the Soviet Union.
Utter distrust between the countries sometimes resulted in
curious incidents. American seismologist J. Evernden, who later
enrolled on the American team of experts in the joint experiments, sent a letter to the journal Science, rebutting false accusations toward the USSR of violating the 150 kt TTBT (Evernden,
1985). At that time, Soviet censors were deleting anything about
the Soviet nuclear testing program from the released copies of
Science. Thus, when the issue reached the USSR , the letter was
censored out, even though it spoke in favor of the USSR .
TECHNICAL STUMBLING BLOCKS
The problem of unequivocal verification of underground nuclear tests was a strong and convenient argument for those opposed to banning nuclear testing. Seismic methods were used
already by both sides at that time for TTBT verification. The
1
Interview with Dr. Jack F. Evernden by Kai-Henrik Barth in Golden,
Colorado in June 16, 1998, Niels Bohr Library & Archives, American
Institute of Physics, College Park, Maryland, http://www.aip.org/
history/ohilist/5914.html.
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seismic array of the USSR Ministry of Defense was able to
detect the yield of explosions in Nevada with an accuracy
of ∼20% for > 1 kt explosions. In Norway, two high-frequency
(> 20 Hz) seismic arrays (the Norwegian Seismic Array
[NORSAR] and the Norwegian Regional Sesmic Array
[NORESS]) monitored the underground nuclear explosions at
Novaya Zemlja and Semipalatinsk from 1968 onward (Nersesov et al., 1991). Nonetheless, opponents of a CTBT claimed
that, without reliable methods of mutual verification, the
United States would never be positive that the USSR did not
continue to test new weapons, enhance the quality of its nuclear power, and gain the chance to change the balance of
forces between the two countries. The U.S. Administration reported to the Congress that “… on several occasions, seismic
signals from the Soviet Union have been of sufficient magnitude to call into question Soviet compliance with the threshold
of 150 kT” (Richards and Zavales, 1990).
The wide range of opinions among scientists allowed the
Reagan Administration to choose a point of view that was convenient for its political purposes. It included the following
technical issues preventing further promotion of nuclear
test bans.
Arguable Reliability of Seismic Methods of Control
A network of high-sensitivity seismic stations capable of
registering even minor seismic events within a distance of thousands of kilometers was estimated to be necessary for efficient
and effective monitoring of underground explosions. Some experts claimed the seismological equipment of the time could
not accommodate this requirement. Moreover, they argued
that it would not be able to differentiate between small earthquakes, industrial explosions, and underground tests. The
Reagan Administration highly supported the Continuous
Reflectrometry for Radius versus Time Experiments (CORRTEX) method, which demands deployment of a hydrodynamic
tube in the close vicinity, within a hundred meters, from the
explosion source (Cochran, 1987).
Alleged Violations of the 150 kt Threshold by the USSR
Such violations were claimed on the basis of comparing seismic-wave magnitude produced by underground nuclear tests in
Nevada and Semipalatinsk.
Potential Methods of Concealing the Increased Yield of
an Explosion (e.g., Decoupling)
Concealment scenarios describing tactics of breaching test ban
treaties were part and parcel of the Cold War; among them
masking an explosion with a nearby earthquake and consecutive multiple explosions (Kedrov, 2005). Another issue that was
used to derail negotiations on nuclear arms control is referred
to as decoupling, which is muffling the seismic signals of the
explosions in large underground cavities. This scheme was
discussed theoretically by Latter et al. (1961) for evasion of
a future CTBT, though this technique was not a threat to the
TTBT, as it was only applicable to weak nuclear explosions. An
experiment on the decoupling effect was conducted by the
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United States in 1966: the underground nuclear explosion
STERLING was detonated in a hollow salt dome in Mississippi. The recorded seismic response at 1–2 Hz frequency was
decreased noticeably (∼60 times compared with a fully coupled
explosion), but it still was considerably less than the theoretically predicted ∼200 times (Herbst et al., 1961) difference. In a
high-frequency band (10–30 Hz), the decoupling was even
weaker (Sykes, 1987). A similar but more powerful ∼8 kt decoupling experiment was carried out by the USSR in 1976
(Adushkin et al., 1993). The cavity was ∼38 m in radius and
had been created by another nuclear explosion. The decoupling
factor was ∼30. Thus, high-frequency seismic signals can still
be used to detect an explosion even with decoupling, because
high-frequency seismic signals could be easily detected to distances well beyond 1000 km (Archambeau, 1986).
There were scientists who debated this point of view.
Some specialists were convinced of the advantage of seismic
monitoring methods over the CORRTEX method, which is
not effective for weak explosions with the yield < 75 kt and
has considerable uncertainty, depending on the geometry of
installation (Kedrov, 2005). Some seismologists were positive
the U.S. initiative favoring CORRTEX was put forward to
hinder progress on a СТВТ.
The concept of independent verification projects had been
brewing in scientific groups like the Pugwash Committee, The
Committee of Soviet Scientists for Peace and Against the
Nuclear Threat, and others for years. Moreover, with the
1980s came the digital revolution of seismic equipment. At that
time, digital techniques of data acquisition became available that
included analog-digital converters in a wide dynamic range, highspeed data-transmission, and large-volume storage devices. Digital
recordings permitted scientists to perform sophisticated data
analyses, to better discriminate the sources of weak seismic signals, and to determine the specific properties of the signal sources.
INITIATION OF THE EXPERIMENT
After a workshop in Moscow, which was devoted to formulating the scientific goals of the joint Soviet–American project, an
agreement was signed on 28 May 1986 between the Soviet
Academy of Sciences and the Natural Resources Defense
Council (NRDC), a U.S. nongovernmental organization, to
conduct seismological experiments in order to assess whether
Soviet underground nuclear tests were verifiable by the
American seismic stations and recording equipment. Another
agreement was signed by A. DeWind (the chairman of the
NRDC Board of Trustees) and E. Velikhov (vice president
of the USSR Academy of Sciences) on 25 June 1987, describing
in full detail the procedures of conducting mutually equal
underground nuclear explosions on both test sites under scientific and technical supervision by the counterparty.
KEY PLAYERS
Because of the stalemate in bilateral politics on nonproliferation of nuclear arms, the experiment being discussed by the
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NRDC and Soviet scientists evolved in an unconventional or-
der. The initiative to bring about this plan was coming from
the scientific communities in the two countries rather than
from the government officials, who had not been urged to give
it a green light. The key roles making it come to fruition were
played by the following organizations and people.
Natural Resources Defense Council (NRDC)
This American nongovernmental organization, founded in
1970 by a group of attorneys and scientists, continues to advocate environmental issues to this day. Although not sufficiently equal academically with the Soviet Academy of
Sciences to be formally acting as an equal counterpart in joint
research, it nevertheless possessed an invaluable quality that
helped its case with the U.S. authorities. Given the highly negative attitude of the Reagan Administration toward collaborating with the Soviet Union, the U.S. government would favor a
relevant independent contractor that could take the shape of a
nongovernmental organization.
From the American side, the project was led by Thomas
Cochran, a physicist and consultant for the NRDC, who
received the 1987 Leo Szilard Award for the experiment in
question. The NRDC played the role of a contractor. It took
care of all organizational issues, purchased the equipment, and
invited leading seismologists from the University of Colorado,
Scripps Institution of Oceanography, University of Nevada,
and others to build the American team of experts. Its ranks
were joined by Charles Archambeau, Jonathan Berger, Jim
Brune, Jack Evernden, Keith Priestly, Lynn Sykes, Holly Eissler,
and others.
Soviet Academy of Sciences
The Academy of Sciences of the USSR was the main scientific
body in the country. It also incorporated the Committee of
▴ Figure 1. Locations of the Semipalatinsk stations. Black triangles indicate American seismic stations, open squares indicate nearest
cities, and the open triangle indicates test site, Regelen. BAY, Bayanaul; KKL, Karkoaralinsk; KSU, Karasu.
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Soviet Scientists for Peace and Against the Nuclear Threat, led
by Evgeny Velikhov, Soviet physicist and vice president of
the Academy of Sciences at the time. This Committee evolved
from cooperation with foreign colleagues, the first being the
Pugwash Committee, and it advocated disarmament and
environmental safety through scientific collaboration. It was
Evgeny Velikhov who was to lead the Russian party in this
project. He was among those whose scientific initiative overcame the political controversies surrounding the verification
issue and the restrictions concerning confidentiality of information and access to nuclear test sites imposed by the U.S.
Department of Defense and the USSR Ministry of Defense.
Institute of Physics of the Earth (IPE)
The best candidate to execute the mission from the Soviet side
was the IPE, the leading Soviet scientific institution in seismology led by Mihkail Sadovsky. One of its strongest departments
was the Integrated Seismological Expedition (ISE), headed by
the prominent seismologist Igor Nersesov. ISE possessed experience on similar projects; it had the relevant test sites and
equipment at its disposal. There were also experts working
at IPE who were qualified to participate in such an experiment
(geophysicists, technicians, and programmers), and some of
them became members of the Russian team of experts, namely
Sergey Negrebetsky, Mikhail Gokhberg, Nikolay Tarasov, Boris
Kazak, and others.
There was another potential hindrance to the progress of
the experiment. The gap between the quality of digital equipment used in the United States and in the USSR was considerable and had to be bridged quickly for this project. A design
and engineering bureau in the Soviet Republic of Georgia was
commissioned to create digital seismic stations almost from
scratch as soon as possible. The laboratory head, Imels Lomtatidze, and construction engineer Akakii Ivanoshvili joined
the Soviet technical team bound for Nevada (Sergey Negrebetsky, personal interview, 2012).
TIMELINE OF THE EXPERIMENT
Phase I
The first stage of the project entailed installing a triangle of
U.S. seismic stations in July–August 1986 in the vicinity of the
Soviet nuclear test site in Semipalatinsk within the 250 km
range from the test site to measure a series of test chemical
explosions (Fig. 1). The American team installed a set of seismometers in 100 m deep boreholes, which allowed them to
record seismic noise from 100 Hz to fractions of millihertz.
In November 1986, a group of Soviet scientists from the
IPE came to the United States to finalize the proceedings for
similar research in the vicinity of the Nevada test site (Fig. 2).
At the initial stage of the project, the U.S. authorities were reluctant to give the Soviet group clearance to access the test site,
and thus the locations for seismic stations had to be chosen
offsite. This was done with the help of seismologists from
the Scripps Institution of Oceanography, who offered a choice
of eight viable locations and provided detailed topographic and
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▴
Figure 2. Locations of the Nevada stations (black triangles).
geological maps of the region, rock specimens, and slides
(Nikolay Tarasov, personal interview, 2013).
Phase II
The second stage of the experiment in 1987 consisted of recording chemical explosions for calibration purposes on both
test sites. This was accomplished by the American team of experts in Kazakhstan in 1987 and by the Soviet team in Nevada
in 1988. The USSR broke the unilateral moratorium and resumed nuclear testing in February 1987, so during the times of
the nuclear explosions, the U.S. stations in Kazakhstan were
demanded to be kept inoperative. Nevertheless, data analysis
of local earthquakes and explosions turned out to be extremely
fruitful, as it allowed the American experts to assess the attenuation of seismic waves in the vicinity of the test site, which in
Kazakhstan appeared to be less than in Nevada (the Russian
Academy of Sciences Archive). This explained the apparent
excess yield of Soviet underground explosions and substantiated the possibility of reliable registration of weak (less than
1 kt) explosions by 30–40 Hz high-frequency seismometers.
Phase II also paved the way to the Joint Verification Experiment in 1988, the objective of which was to observe and
seismically record nuclear explosions (as opposed to chemical
ones in the discussed experiment) at short (< 750 km) and
long (> 2500 km) distance ranges using American seismic stations in Kazakhstan and Soviet stations in the United States.
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(Priestley et al., 1990) This experiment provided an opportunity to test methods for the yield estimate, in particular the
yield– Love-wave relationship developed in other regions.
These are no longer amateur activities of the scientific community, but the responsibility of official military establishments”
(Russian Archive of film and photo documents).
Phase III
The third experiment stage, in 1988–1989, consisted of data
exchange and comparisons between the parties, publication of
results, and making the results public. Curiously, the experiments that were widely advertised in the United States did not
receive much publicity in the Soviet Union, presumably due to
differences in national policies on the confidentiality issue. The
Nuclear Smallpox, a Soviet documentary directed by Pyotr
Mostovoy, was released in 1988 and contained footage of the
nuclear test sites and explosions performed during the experiments, as well as interviews with American and Soviet seismologists and both E. Velikhov and T. Cochran. The film also gave
an analytic commentary offered by the reputed political scientist and journalist Alexander Bovin. It reveals the public level of
esteem for science of that time. While describing the 1988
meeting between Reagan and Gorbachev in Moscow as the
culmination of political achievements of the year, the commentator proclaims: “Scientists have passed the baton to politicians.
RESULTS OF THE EXPERIMENTS
The project’s aim was to demonstrate to the governments of
both countries that even very small explosions could be detected by sensitive equipment over large distances. Were the
United States and Soviet Union to agree to a nuclear test
ban, such a monitoring capability would be a means of policing
the treaty. A test ban, in turn, would help slow down the arms
race, because the development of new weapons depends on
underground testing.
The main result of the joint experiment was a compelling
demonstration to society of the current state of the problem
and of the technical means to solve it, thus significantly limiting opportunities for political speculation. Because the experiments showed that a chemical underground explosion 1000
times weaker than an average nuclear one can be detected teleseismically, there was not much argumentation left to use
against further advancement of arms control.
▴ Figure 3. Seismograms and spectra from an earthquake and an explosion indicate the different sources are distinguishable even to an
untrained eye.
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Reliability of Seismic Methods: Distinguishing between
Earthquakes and Explosions
Professional seismologists were sure that the concern of some
arms negotiators that a country might try cheating by camouflaging small nuclear tests during earthquakes was entirely overblown. Though to the untrained eye seismic signals from an
earthquake and explosion are hardly distinguishable from
one another, a professional analysis reliably discriminates them
by the larger high-frequency spectral content in the explosion’s
signal (see seismograms and spectra from an earthquake and an
explosion in Fig. 3). The experiments demonstrated to the general public that natural and man-made earth tremors can be
identified, and the precise location and size of a human-induced explosion can be determined.
A curious incident that happened in Kazakhstan during
the second stage of the experiment provides a perfect illustration of the level of verification. As the Amicus Journal
described, “less than 2 minutes before the TNT was set to go
off, the recording pen of the seismograph began to twitch.
Someone assumed that the blast had gone off slightly prematurely. But Dr. Holly Eissler, a seismologist from the University
of California at San Diego, quickly recognized even without
spectral analysis the signal as that of an earthquake, most likely
in the western Pacific. The explosion of TNT was on schedule,
and 25 seconds into the earthquake its shock waves indeed
reached the station” (Nuclear Glasnost, 1987).
Reliability of Seismic Methods: Determining the Exact
Location and Yield of the Explosion
From the interviews with the Russian participants and the papers published as a result of the projects, it became clear that
seismological methods of detecting underground nuclear explosions could accurately trace their locations. However, the question of yield also had to be dealt with and was successfully
resolved during the experiments. It turns out that the strength
of seismic signals is affected by the attenuation in the geological
media through which they pass. The American team confirmed
a drastic difference between the high-frequency seismic-wave
attenuation in the crust in Kazakhstan and Nevada, and they
indicated that a previously incorrect accounting of this difference had led to biased estimates of Soviet nuclear tests and
claims that they were violating the Threshold Treaty of 1974.
When this correction for lower attenuation in Kazakhstan
crust was proven, the issue of possible violations by the USSR
of the upper limit of 150 kt was finally resolved in favor of
the USSR .
Detecting and Exposing Methods of Cheating on Test
Bans
As described earlier, another issue that used to delay negotiations on nuclear arms control is referred to as decoupling. The
experiments put to rest the nagging concern that it is possible
to cheat on a low-threshold test ban treaty. The results obtained by the Soviet team at the Nevada test site and U.S. team
in Semipalatinsk made it apparent that high-frequency seismic
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signals could be easily detected to distances well beyond
1000 km.
All the above results were not surprising for professional
American and Soviet seismologists, who had suspected many of
the results (Evernden, 1988). Thus, from the academic point of
view, this experiment did not provide any new fundamental
knowledge. However, it demonstrated the capabilities of
modern seismology to decision makers at the top level of society, and thus it had a great social impact. The experiment was a
truly unique enterprise, regrettably not very common for relationships between science and politics nowadays.
CONCLUSION
This project finished in 1989; and, encouraged by this
precedent, further negotiations and other joint activities incrementally led to a completely different level of political understanding between the United States and USSR on nuclear arms
control issues. The fact that many scientific problems faced by
seismologists in this project were solved during the experiments
shows that the whole project was not entirely a political exercise and that scientists—in this case seismologists—could use
well-designed and objective experimentation to examine the
dubitable claims of the reliability of seismic verification and
the possibility of cheating on test bans, which had been fostering mutual distrust in the course of international politics of the
twentieth century. Viewed as a feature of a much larger picture
of eliminating the global nuclear threat of the Cold War, the
joint Soviet–American experiments in underground nuclear
explosion verification proved to be a stepping stone toward the
Comprehensive Nuclear-Test-Ban Treaty by means of international scientific cooperation. The experiments played a key
role in showing that the geosciences possess the tools and
knowledge for revealing the truth to society.
DATA AND RESOURCES
Russian Academy of Sciences Archive, Record Number 1564,
Catalog Number 1, Folder Number 849, 34 Novocheremushkinskaya St., 117218 Moscow, Russia. Russian Archive of film
and photo documents, item no. 29908, Yadernaya Ospa (Nuclear Smallpox), http://rgakfd.ru/catalog/films/ (last accessed August 2014) (in Russian).
ACKNOWLEDGMENTS
I am grateful to members of the Russian team of experts B.
Kazak, M. Gokhberg, S. Negrebetsky, and N. Tarasov for interviews they gave and materials they provided, to V. Pilipenko for
his expertise and support, and to O. Starovoit for his invaluable
recommendations, corrections, and encouragement.
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Seismological Research Letters
Anna Amramina
Institute of Physics of the Earth
10 Bolshaya Gruzinskaya Street
Moscow 123995, Russian Federation
[email protected]
Published Online 11 February 2015
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