Threshold Test Ban Treaty Research Articles

Project Plowshare: The Peaceful Use of Nuclear Explosives in Cold War America

Project Plowshare: The Peaceful Use of Nuclear Explosives in Cold War America

The instrument responses of the SKM-3 system and the Designated Seismic Station Vault Seismic System

Abstract We present the system transfer functions and responses due to inputs of impulses in ground displacement, velocity, acceleration, and acceleration integral of the two systems: the SKM-3 system of the former Soviet ESSN (Unified Seismic Observation System) and the Designated Seismic Station (DSS) Vault Seismic System (VSS) used by the United States for monitoring the Threshold Test Ban Treaty (TTBT) protocol at the in-country DSS sites of the Commonwealth of Independent States (CIS). We show that the amplitude of the transfer function formulas for the electromagnetic seismograph used by the former Soviet Union seismologists can be analytically traced back to the original Hagiwara's equation. This thereby allows us to restore the phase to the CIS's version. Some examples of instrument deconvolution/convolution are given using various system transfer functions of the SKM-3 and DSSVSS.

The politics of verification: Limiting the testing of nuclear weapons

From 1982 to 1990, the United States and the Soviet Union renegotiated verification arrangements for two unratified arms control agreements that had nevertheless been observed since 1977: the Threshold Test Ban Treaty and the Peaceful Nuclear Explosions Treaty. The negotiations yielded new verification procedures, changed attitudes regarding Soviet compliance, and established useful precedents for further restrictions on nuclear testing. The negotiations also demonstrated how technical arguments can be misused to promote a particular political agenda—in this case, the continued testing of nuclear weapons. By misrepresenting the uncertainties in US monitoring procedures, and then falsely characterizing these uncertainties as a fatal flaw of seismic verification techniques, opponents of a nuclear test ban clouded the sensitive issue of verification enough to delay progress towards a complete ban on nuclear weapons testing. The primary obstacle to further restrictions on nuclear testing was not the feasibili...

Calibrated Seismic Verification of the Threshold Test Ban Treaty

Calibrated Seismic Verification of the Threshold Test Ban Treaty

Calibrated Seismic Verification of the Threshold Test Ban Treaty

Abstract To improve verification of the Threshold Test Ban Treaty, the United States and Russia have embarked on an effort to make on-site yield measurements of each other's nuclear tests. Beyond their direct use in verification, these measurements also may prove useful in calibrating a monitoring system based on seismic magnitudes. The relative merits of seismic monitoring vis-a-vis on-site measurement have been at the core of a long-standing controversy. Many seismic verification problems hinge on statistical issues, including linear calibration based on a small data set and the formal use of expert opinion.

The stability of rmsLgmeasurements and their potential for accurate estimation of the yields of Soviet underground nuclear explosions

AbstractData on underground nuclear explosions have recently become available from modern digital seismic stations installed within the Soviet Union and China. Observations of root mean square (rms) Lg-wave signals for Soviet underground nuclear explosions at the Shagan River Test Site in East Kazakhstan show that the relative amplitudes of the rms signals at stations in Norway, the USSR, and China are very similar for different explosions, the standard deviation of the differences being only about 0.03 in logarithmic units (i.e., magnitude units).This is consistent with earlier observations comparing NORSAR and Graefenberg array data, and the observed scatter is significantly lower than has been reported for Lg data from Nevada Test Site explosions. In view of the excellent correspondence found by Nuttli (1986) and Patton (1988) for Lg versus yield at Nevada, this indicates that rms Lg has a potential for yield estimation with very high accuracy at Shagan River.Our study has shown that: (a) selected stations in the USSR and China, situated at regional distances, provide a much improved signal-to-noise ratio of the Lg phase for events at Shagan River, as compared to NORSAR array data; (b) the scaling of rms Lg amplitudes between different-sized events recorded at the same single station site appears to be consistent with that of NORSAR, indicating a remarkable degree of precision in single station measurements of Lg signal; (c) rms Lg amplitude measurements for the best of these stations may be made at 1.5 to 2.0 magnitude units lower than at NORSAR or Graefenberg, allowing a much lower threshold for Lg-based yield determination; and (d) the P-wave detection capabilities of these single stations do not match those of the NORESS and ARCESS arrays; thus, teleseismic signals continue to be important for detection of small nuclear explosions.Our conclusion is that Lg signals appear to provide an excellent basis for supplying estimates of the yields of nuclear explosions even down to below 1 kt when such signals are recorded at high-quality, digital in-country seismic stations, and when calibrated by access to independent (nonseismic) yield information for a few nuclear explosions at the test sites of interest. In the context of monitoring a low-yield threshold test ban treaty, it will, in addition, be important to take into consideration various environmental conditions in the testing area, such as the possible presence of cavities, and to devise appropriate procedures for on-site observations in this regard.

Comparison of seismic and hydrodynamic yield determinations for the Soviet joint verification experiment of 1988

Seismic magnitudes determined from surface and body waves for the Soviet underground nuclear explosion of September 14, 1988, are used to calculate the yield of that event from previously derived calibration curves. The yield obtained by combining the two seismic estimates is 113 kilotons, which is very close to those obtained by hydrodynamic measurements made on-site. This comparison substantiates previous conclusions about the sizes of past Soviet weapons tests and compliance with the Threshold Test Ban Treaty. The factor of uncertainty in the combined seismic yield is 1.28 at the 68% and 1.62 at the 95% confidence levels, demonstrating that accuracies considerably better than a factor of 2 can be obtained by combining seismic determinations of yield.

Yields of US and Soviet Nuclear Tests

The likelihood that the United States will negotiate a comprehensive or lowthreshold test ban treaty with the Soviet Union in the relatively near future depends not only on the ability of the US to monitor such an agreement but also on US perception of past Soviet compliance with treaties that limit nuclear testing. Of particular importance is the 1974 Threshold Test Ban Treaty, which prohibits tests of nuclear weapons exceeding 150 kilotons in yield. This treaty is unratified, but both the United States and the Soviet Union have avowed their compliance since 1976, when the treaty was scheduled to go into effect. (For an annotated list of treaties, see Herbert York's article in PHYSICS TODAY, March 1983, page 24.)

Yields of Soviet underground nuclear explosions from seismic surface waves: Compliance with the Threshold Test Ban Treaty

Magnitudes of the larger Soviet underground nuclear weapons tests from the start of the Threshold Test Ban Treaty in 1976 through 1982 are determined for short- and long-period seismic waves. Yields are calculated from the surface wave magnitude for those explosions at the eastern Kazakh test site that triggered a small-to-negligible component of tectonic stress and are used to calibrate body wave magnitude-yield relationship that can be used to determine the sizes of other explosions at that test site. The results confirm that a large bias, related to differential attenuation of P waves, exists between Nevada and Central Asia. The yields of the seven largest Soviet explosions are nearly identical and are close to 150 kilotons, the limit set by the Threshold Treaty.