Overview of the verification regime
The verification regime of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is designed to detect any nuclear explosion conducted on Earth – underground, underwater or in the atmosphere.
The purpose of the verification regime is to monitor countries’ compliance with the CTBT which bans all nuclear explosions on the planet.
Besides promoting the CTBT, the main task of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is to build this regime and to ensure that it is operational by the time the Treaty enters into force.
The CTBT’s global alarm system is designed to detect any nuclear explosion conducted on Earth – in the underground, underwater or in the atmosphere.
The verification regime consists of the following elements:
- International Monitoring System
- International Data Centre
- Global Communications Infrastructure
- Consultation and clarification
- On-Site Inspection
- Confidence-building measures
The International Monitoring System (IMS)
The CTBTO’s International Monitoring System consists of 337 facilities located all over the world.
Four verification technologies
The IMS uses four complementary verification methods, utilizing the most modern technology available. Seismic, hydroacoustic and infrasound stations monitor the underground, the large oceans and the atmosphere respectively.
Radionuclide stations detect radioactive debris from atmospheric explosions or vented by underground or underwater nuclear explosions. Radionuclide laboratories assist radionuclide stations in identifying these radioactive substances.
To learn more, please visit the area on the four technologies.
The IMS uses four different technologies – seismic, hydroacoustic, infrasound and radionuclide – to monitor the planet for nuclear explosions.
IMS monitoring stations and laboratories will operate in 89 countries around the world. Establishing them poses engineering challenges unprecedented in the history of arms control. Many stations are located in remote and inaccessible regions of the globe.
IMS monitoring stations and laboratories will operate in 89 countries around the world.
Once established or upgraded and certified as meeting all technical requirements, monitoring stations and radionuclide laboratories are operated by local institutions under contracts with the CTBTO.
The building and operation costs of the facilities (except for auxiliary seismic stations) are paid for by the CTBTO.
To get a good overview of all the facilities and where they are located in the world, click here.
The International Data Centre (IDC)
The IMS is supported by an International Data Centre (IDC), located at the headquarters of the CTBTO in Vienna, Austria. The IDC processes and analyses the data registered at the monitoring stations, and produces data bulletins that are submitted to the Member States for their evaluation and judgement.
The IDC assists Member States in assuming their verification responsibilities by providing capacity building services necessary for effective global monitoring.
Processing of data
The incoming data are used to register, locate and analyse events, with emphasis to detect nuclear explosions. Data are processed immediately, with the first automatic analysis – a so-called data bulletin – released within two hours.
Data from the International Data Centre in Vienna are used to register, locate and analyse events, with emphasis to detect nuclear explosions.
Data bulletins comprise lists of automatically analysed seismo-acoustic events and radionuclides detected by the monitoring stations. Analysts subsequently review these lists to prepare quality-controlled bulletins for the Treaty’s Member States.
Transmission of data to Member States
The IDC has been providing IMS raw data and IDC data bulletins to Member States since 21 February 2000.
Raw data and data bulletins are being transmitted since 21 February 2000.
Secure signatory accounts have been established to allow Member States to access these data and products.
Extensive support is given to the users designated by the Member States by providing a standard software package, training courses and technical assistance.
For more information, please visit our workshops and training area.
To learn more, please visit our area on the International Data Centre.
The Global Communications Infrastructure (GCI)
The Global Communications Infrastructure (GCI) transmits the data recorded at the IMS stations to the International Data Centre (IDC). It also transmits raw data and data bulletins from the IDC to the Member States.
The GCI ensures global coverage. Data are received and distributed through a network of six satellites. The satellites route the transmissions to three hubs on the ground, and the data are then sent to the IDC by terrestrial links.
The GCI ensures global coverage. Data are received and distributed through a network of six satellites.
To learn more, please visit our area on the Global Communications Infrastructure.
Consultation and Clarification
If a Member State feels that certain data collected imply a nuclear explosion, a consultation and clarification process can be undertaken to resolve and clarify the matter. This process, which will be available to Member States after the Treaty’s entry into force, allows a State to request clarification directly from another State or through the Executive Council. Member States can also request information from the Director-General of the CTBTO . A State that received such a request has 48 hours to clarify the event in question.
On-site inspections (OSI)
States have the right to request an on-site inspection, regardless of the results of the consultation and clarification process. Such inspections will be carried out to ascertain whether a nuclear explosion has occurred in violation of the Treaty. They will also be used to collect facts that might be of use in identifying possible violators. On-site inspections are regarded as the final verification measure under the Treaty and can only be invoked once the Treaty enters into force.
To learn more, please visit our area on on-site inspections.
On a voluntary basis, Member States are to notify the CTBTO Technical Secretariat in case of any chemical explosion using 300 tonnes or more of TNT-equivalent blasting material detonated on their territories. These notifications serve two purposes. First of all, they contribute to the resolution of any eventual misinterpretation of verification data so that for example a large mining explosion is not initially thought to be a nuclear explosion. Secondly, they assist in the testing and fine-tuning of the IMS network.
Member States are to voluntarily notify the Technical Secretariat of any chemical explosion involving 300 tonnes or more of TNT-equivalent on their territories.
To read more about the Verification Regime, how it came about, how it was established and how it works, please read the interview with Ola Dahlman.
Dr Dahlman was the chairman of the Group of Scientific Experts that worked out the details of the verification regime before and during the negotiations of the CTBT, and the chairman of the CTBTO Working Group on verification from 1996-2006.