Comprehensive Test Ban TreatyFrom the CTBTO website:
"The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a cornerstone of the international regime on the non-proliferation of nuclear weapons and an essential foundation for the pursuit of nuclear disarmament. Its total ban of any nuclear weapon test explosion will constrain the development and qualitative improvement of nuclear weapons and end the development of advanced new types of these weapons.
The Comprehensive Nuclear-Test-Ban Treaty was adopted by the United Nations General Assembly, and was opened for signature in New York on 24 September 1996. It has achieved strong worldwide support.
The Treaty will enter into force after it has been ratified by the States listed in its Annex 2. These 44 States formally participated in the 1996 session of the Conference on Disarmament, and possess nuclear power or research reactors. "
The CTBT's extensive verification regime includes: an International Monitoring System, an International Data Center, on-site inspections, and confidence-building measures. The International Monitoring System will be composed of four global monitoring regimes; 1) seismological, with 50 primary stations and 120 auxiliary stations; 2) radionuclide, with 80 stations monitoring particulates and 40 stations (to be extended to 80 in the future) monitoring noble gases; 3) hydroacoustic, (monitoring for sound waves caused by a nuclear explosion in the ocean), with 11 stations; and 4) infrasound (monitoring for very low frequency sound waves in the atmosphere which could be caused by a nuclear explosion), with 60 stations. The International Data Center, to be accessible to all States Parties, will receive, collect, process, analyze, report on, and archive data from International Monitoring System facilities. On-site inspections, to determine whether a suspected nuclear explosion detected by the monitoring stations actually occurred, can have three phases: 1) overflight/visual observation, photography, radioactivity measurement, environmental sampling, and passive seismic monitoring for aftershocks; 2) active seismic surveys, to locate underground anomalies, plus magnetic and gravitational field mapping, ground-penetrating radar surveys and electrical conductivity measurements; and 3) drilling to obtain radioactive samples.