About this tour
This virtual tour provides an overview of the CTBT verification technologies of the International Monitoring System: radionuclide (noble gas and particulate), seismic, hydroacoustic and infrasound.
Explore the facilities at CTBTO headquarters in Vienna, Austria, which are used to test equipment, and also serve an important training and outreach function. This tour also includes images of an operational hydroacoustic Central Recording Facility and an overview of the infrastructure required to capture and transmit hydroacoustic data to the International Data Centre.
About the IMS
The International Monitoring System (IMS) is at the heart of the CTBT verification regime. It consists of a global network of 337 IMS facilities: 321 monitoring stations and 16 radionuclide laboratories. The IMS is designed to detect any sign of a nuclear explosion underground, underwater and in the atmosphere. The composition of the IMS and the location of stations were determined during the negotiations of the CTBT.
The full list of facilities, including their geographic coordinates and type, is contained in Annex 1 to the Protocol to the CTBT (view the Treaty text here). Click on the image of the map below to visit the interactive IMS map on the CTBTO website.
Virtual Tour Scenes
These tours will provide you with examples of the various components, equipment and configuration of IMS facilities for each monitoring technology: hydroacoustic, infrasound, radionuclide (noble gas and particulate systems) and seismic.
Hydroacoustic Monitoring
Where: 11 stations in eight countries around the world - six underwater hydrophone stations and five T-phase stations on land.
How: Two sensing techniques: underwater microphones, called hydrophones, at the six hydrophone stations and seismometers on steep-sloped coastlines at the five T-phase stations. Water is an efficient conductor of acoustic waves, so eleven stations are sufficient to monitor the world's oceans.
Learn more: Hydroacoustic monitoring on ctbto.org
Infrasound Monitoring
Where: 60 IMS stations in 35 countries around the world.
How: Infrasound sensors, known also as microbarometers, measure micropressure changes in the atmosphere that are generated by the propagation of infrasonic waves. These very low frequency waves can also be created by atmospheric nuclear explosions.
Learn more: Infrasound monitoring on ctbto.org
Radionuclide Monitoring
Where: 80 IMS radionuclide stations and 16 laboratories, in 27 countries around the world. A total 40 of the 80 IMS radionuclide stations are designated to have additional noble gas detection capabilities.
How: Airborne particles are captured for analysis to identify the radioactive elements, or radionuclides, contained in them. In a separate process, air is sampled with noble gas systems to detect the radioactive noble gas xenon content. Detection of specific radionuclides provide unambiguous evidence of a nuclear explosion.
Learn more: Radionuclide monitoring on ctbto.org
Seismic Monitoring
Where: 170 seismic stations - that is 50 primary and 120 auxiliary seismic stations - in 76 countries around the world.
How: Seismic stations are equipped with seismometers to measure waves generated by seismic events (for example, earthquakes or explosions) that have propagated through the Earth. Measurements taken at seismic stations help identify the location, strength and nature of seismic events.
Learn more: Seismic monitoring on ctbto.org