The CTBT and its verification regime discussed in Washington DC, USA

The International Monitoring System of the CTBTO Preparatory Commission will soon have another station in test mode operation. In February 2007, the installation of hydroacoustic station HA11 at Wake Island was completed. Six hydrophones, or underwater microphones, were deployed, in two groups of three, at two locations about 100 kilometres north and south of the island. Additional work involved the laying of cables to, and the construction of facilities on, the island.

The station is now being tested before being certified later this year. Certification confirms that a station meets all technical requirements set by the CTBTO Preparatory Commission. Following certification, the station will join the test mode operation of the International Monitoring System (IMS).

The IMS plays a central role in monitoring compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The verification regime of the CTBT is unique. It consists of 321 facilities using four different technologies to monitor the globe for nuclear explosions - seismic, infrasound, hydroacoustic and radionuclide - and is supported by a network of 16 radionuclide laboratories. The CTBT stipulates that the verification regime must be operational when the Treaty enters into force.

In April 2007, the installation of about 75% of the 321 monitoring stations, including the hydroacoustic station at Wake Island, had been completed. Another 40 stations were either being constructed or the installation contract was under negotiation. More and more stations are being certified before going into test mode operation.

The maps above show the status of station installation for each technology. The various phases are colour-coded and span the entire spectrum from stations planned, over stations under construction, to completed stations transmitting data and certified stations.

Once stations are certified they send data continuously to the International Data Centre in Vienna. These data are analyzed and then made available in the form of data products. These products are currently distributed to 800 institutions in nearly one hundred countries.

It becomes clear from looking at these maps how far the process of station building has progressed. The majority of stations are depicted in black indicating already certified stations. There are still many stations awaiting installation or certification. By 2008, however, the CTBTO Preparatory Commission plans to have 90% of the IMS network installed. This poses a number of challenges. The stations yet to be built often are located in environmentally difficult or extremely remote places and hence are very costly to build. In some cases, political conditions are an impediment.

With an increasing number of stations running in test mode operation, the IMS has begun to focus on the sustainability of its system. Strategies are being developed to address operation and maintenance of IMS stations. In addition, equipment and facilities will increasingly become outdated and be in need of replacement based on new and improved technologies.