AGU and SSA Issue Joint Statement on Test Ban Treaty

The American Geophysical Union (AGU) and the Seismological Society of America (SSA) issued a joint position statement on the capability to monitor compliance with the Comprehensive Test Ban Treaty (CTBT) at a press conference on October 6. The statement was presented by Terry Wallace, chair of the drafting committee and President of SSA, Gregory van der Vink, originator of the statement and member of the AGU Committee on Public Affairs, and Jeffrey Park, President-elect of AGU's Seismology Section. The drafting Committee also included Paul Richards, Howard Patton, and Brian Stump.

The statement, reprinted below, reviews the technical capabilities to monitor a CTBT and calls for all data from the International Monitoring System to be made openly available without any restriction or delay.

The statement was also presented to staff of the Senate Foreign Relations Committee, discussed at a White House reception, reported in The New York Times, and was covered on NBC, CNN, and FOX news networks.

Although the Senate failed to ratify the treaty, there is little doubt that the issue will re-emerge. The position statement has received high praise and was well-received even by treaty opponents, because it stuck to the technical issues and avoided the appearance of being self-serving. (see discussion on the statement "Test Ban Tumult Worth the Effort" in the December 1999 issue of GEOTIMES).

Capability to Monitor the Comprehensive Test Ban Treaty

   In September 1996, the United States was the first of 152 nations to sign the Comprehensive Test Ban Treaty (CTBT), an international agreement to ban all nuclear test explosions. The treaty is intended to impede the development of nuclear weapons as part of the international nonproliferation regime. The treaty is as yet unratified by the US As a result, many of its verification provisions have not yet been fully implemented. When implemented, the American Geophysical Union (AGU) and the Seismological Society of America (SSA) are confident that the combined worldwide monitoring resources will meet the verification goals of the CTBT.
    The CTBT will be monitored by: 1) the national intelligence means of various countries, 2) the International Monitoring System (IMS) negotiated under the CTBT that consists of seismic, hydroacoustic, radionuclide, and infrasound networks, along with on-site inspections, and 3) the efforts of numerous independent scientists and institutions worldwide. It is this combination of resources that gives confidence in the ability to uncover CTBT violations. AGU and SSA believe that this overall monitoring capability will continue to strengthen as more data are collected, more research is performed, and as global communication networks expand.
    The seismic component of the International Monitoring System is to consist of 170 seismic stations. This network is expected to detect all seismic events of about magnitude 4 or larger and locate those events within 1000 square kilometers (a circle with a diameter of approximately 35 km). This is the maximum area permitted by the treaty for an on-site inspection. A seismic magnitude of 4 corresponds to an explosive yield of approximately 1 kiloton (the explosive yield of 1,000 tons of TNT). AGU and SSA believe that the verification system, if built as planned, can be relied upon to meet that goal.
    One of the biggest challenges to monitoring the CTBT is the possibility that testing could be successfully hidden by conducting nuclear explosions in an evasive manner. The concern is partly based on US and Russian experiments which have demonstrated that seismic signals can be muffled, or decoupled, for a nuclear explosion detonated in a large underground cavity. The decoupling scenario, however, as well as other evasion scenarios, demand extraordinary technical expertise and the likelihood of detection is high. AGU and SSA believe that such technical scenarios are credible only for nations with extensive practical testing experience and only for yields of at most a few kilotons. Furthermore, no nation could rely upon successfully concealing a program of nuclear testing, even at low yields.
    Data from the treaty's monitoring system will also contribute to our scientific understanding of the Earth and efforts to mitigate earthquake hazards. Article IV.A.10 of the treaty states "The provisions of this treaty shall not be interpreted as restricting the international exchange of data for scientific purposes". AGU and SSA support a broad interpretation of this article and strongly urge that all data from the International Monitoring System be made openly available without any restriction or delay.