The Comprehensive Nuclear Test-Ban Treaty (CTBT), which bans any nuclear weapon test explosion or any other nuclear explosion, was opened for signature on September 24, 1996. As of May 2005, the Treaty has been signed by 175 countries and ratified by 120. To date, 33 of the 44 States listed under Article XIV as States that must sign and ratify the CTBT before it can enter into force have ratified the Treaty. Canada signed the Treaty on September 24, 1996, and ratified it on December 18, 1998. The CTBT provides for a global verification regime, which will eventually include a network of 321 stations worldwide, a global communications system, an international data centre and on-site inspections to monitor compliance. To date, 205 IMS stations (64%) have been installed.

International Monitoring System (IMS)

To ensure compliance in all environments - underground, underwater, and in the atmosphere, an International Monitoring System (IMS) of sensor platforms incorporating four different technologies is being developed and deployed. These technologies comprise seismic (measuring acoustic vibrations in the earth), hydroacoustic (vibrations in the oceans), infrasound (pressure waves in the atmosphere), and radionuclide (radioactive particles in the air). Canada supports all four technologies. More detailed information on the various monitoring systems can be obtained from the CTBTO Preparatory Commmission in Vienna, Austria.

In Canada, Natural Resources Canada (NRCan) is responsible for the operation, installation, and maintenance of IMS facilities related to seismological, infrasound, and hydroacoustic monitoring. NRCan is also tasked with setting up and operating the Canadian NEM Data Centre for the exchange of IMS data with the International Data Centre in Vienna. Responsibility for operating particulate and noble gas radionuclide stations lies with the Radiation Protection Bureau, Health Protection Branch, of Health Canada.

For an overview of the various IMS technologies, and to see maps of the worldwide distribution of monitoring stations for each, click on one of the images below.

Seismic	Infrasound
Hydroacoustic	Radionuclide

Links Related to the Treaty:

• CTBTO PrepCom posting on the complete Treaty Text, various summaries, and a keyword search.
• An introduction, history, and analysis of the CTBT from a Canadian perspective.
• United Nations Department for Disarmament Affairs.