Maps of Monitoring Facilities
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The International Monitoring system (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. This network registers shock waves emanating from a nuclear explosion underground, in the seas and in the air, as well as detecting radioactive debris released into the atmosphere.

In April 2007, the installation of about 75% of the 321 monitoring stations had been completed. Another 40 stations were either being constructed or the installation contract was under negotiation. More and more stations were being certified, meaning that they meet all technical requirements set by the CTBTO PrepCom, before going into test mode operation.

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. All State Signatories are entitled to these products. Over 200 stations were transmitting data to the IDC by April 2007. The data products were distributed to 800 institutions in nearly one hundred countries.

Primary Seismic Network
Auxiliary Seismic Network
Infrasound Network
Hydroacoustic Network
Radionuclide Network
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The above maps 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.

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.