The Current Status of the CTBTO International Monitoring System

Peter Basham

Introduction

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) was opened for signature at the United Nations in New York on 24 September 1996. At the time of writing (October 2000) the Treaty has been signed by 160 States and ratified by 63 States. The Preparatory Commission for the CTBT Organization was established on 19 November 1996 at a meeting of States Signatories. The Provisional Technical Secretariat (PTS) of the CTBTO, the agency responsible for establishing the verification system for the CTBT, took up its work in Vienna on 17 March 1997.

This paper presents a brief account of the current status of the development of the International Monitoring System (IMS), including the International Data Centre (IDC) and the Global Communications Infrastructure (GCI). It also presents a projection of the expected status of the IMS stations at the end of 2001, assuming Preparatory Commission approval of the draft 2001 Programme and Budget, which is currently under consideration by States Signatories, at its November 2000 session.

The International Monitoring System Stations

Establishment of the 321 IMS stations in 90 countries is considered to be among the most challenging tasks in establishing the verification system. Progress in establishing the IMS stations may be measured in three categories: (1) site surveys completed, (2) stations installed and sending data to the IDC, and (3) stations certified. The site surveys are important in establishing that the sites chosen during the Treaty negotiations, or nearby sites if the Treaty locations are found to be unsuitable, are suitable for IMS stations. The number of stations installed and sending data is important because it measures the proportion of the final networks that are contributing to IDC products. The number of stations certified is important because it indicates the number of stations that have been accepted as meeting all PTS standards and are officially incorporated into the verification system. The number of primary seismic, infrasound, hydroacoustic and radionuclide stations in each of these categories is shown in Table 1. "To date" indicates the current status; projections are also made for the end of 2000 and the end of 2001. Auxiliary seismic stations are described separately below.

Site surveys have been completed, or were found unnecessary for some existing stations, for a large majority of the primary seismic stations (Table 1(a)). In the other technologies, roughly half of the site surveys have been completed. In the infrasound and hydroacoustic technologies these have all been new stations requiring site surveys. In the radionuclide technology all of the site surveys have also been done anew, but some data was available for some sites from previously existing national environmental monitoring stations.

Table 1(a) Numbers of IMS Stations with Site Surveys Completed

Technology To Date End 2000 End 2001 Primary Seismic (50) 46 46 48 Infrasound (60) 25 30 58 Hydroacoustic (11) 5 7 9 Radionuclide (80) 49 55 78

Table 1(b) Numbers of IMS Stations Installed and Sending Data to the IDC

Technology To Date End 2000 End 2001 Primary Seismic (50) 18 22 34 Infrasound (60) 5 9 29 Hydroacoustic (11) 3 4 8 Radionuclide (80) 6 9 42

Table 1(c) Numbers of IMS Stations Certified

Technology To Date End 2000 End 2001 Primary Seismic (50) 3 7 21 Infrasound (60) 0 5 22 Hydroacoustic (11) 0 1 5 Radionuclide (80) 0 9 34

The number of stations installed and sending data to the IDC to date indicated in Table 1(b) are the numbers of stations upgraded or established by the PTS, or through gifted or reduced assessment national funding. They do not include additional stations in all technologies that are contributing data voluntarily to the prototype IDC and onward to the IDC (see IDC section below).

Certification of stations, the formal process of accepting stations as meeting all technical requirements of the PTS, is considered by States Signatories as an important measure of progress in developing the IMS. These have been slow in coming primarily because the implementation plan for authentication, required for certification, was not available until mid 1999. This process is now advancing quickly, with three primary seismic stations having been certified in July 2000, and as many as 20 stations, including all technologies, may be certified before the end of the year.

The 120 auxiliary seismic stations selected during the Treaty negotiations were selected primarily from lists of existing stations. With these stations operated for other national purposes, it was considered that money would be saved by the PTS in not having to build or operate these stations. The PTS has recently undertaken a detailed assessment of the technical state of the auxiliary seismic stations. It found that 62% of these stations essentially meet PTS technical specification, except for authentication devices and a GCI connection to the IDC. The other 38% will require substantial work, ranging from a major upgrade to some new stations that will need to be constructed at new sites. Because of the wide range of conditions that we find with the auxiliary seismic stations they did not fit easily into the categories of Table 1 and were therefore not included in that table. The PTS work on auxiliary seismic stations has been concentrated on, firstly, establishing new stations where they previously did not exist or were in a very poor technical state, and, secondly, undertaking the developments that would provide authentication and a GCI connection for many of the stations operated by national and international network operators that essentially meet PTS technical specifications. This strategy will likely continue, and it is expected that the auxiliary seismic network can be brought to completion in the same time frame as the other networks.

The statistics provided for radionuclide stations in Table 1 refers to radionuclide particulate stations. The Treaty states that 40 of the 80 radionuclide stations will also have noble gas monitoring equipment at entry-into-force of the Treaty. The PTS is currently experimenting with four brands of noble gas monitoring equipment, operated side by side, at the Institute for Atmospheric Radioactivity in Freiburg, Germany. Phase 3 of this experiment, to begin in early 2001, will place the four experimental units in actual station environments which will sample a variety of climatic conditions. Decisions will be made in late 2001 on a possible extension of Phase 3 of the experiment.

The International Data Centre

The physical facilities for the IDC were essentially completed in 1999 at the Vienna International Centre. The IDC build-out is now at the end of Phase 4 (Initial Testing of the IDC) of the seven phases that will bring the IDC to operational readiness. The applications software for the IDC is being developed at the prototype IDC in Arlington VA, USA, and delivered to the Vienna IDC in four Releases. The IDC staff are currently installing and testing Release 3, which will provide for Phase 5 of the commissioning plan, full scale testing of the IDC.

About 100 IMS stations in all four technologies are now contributing data to the IDC. These include stations in addition to those described above as established by the PTS, stations that began contributing data voluntarily to the prototype IDC under the GSETT-3 experiment, or, at a later stage began contribution voluntarily in order for the IDC to have sufficient data to test and develop processing procedures.

In February 2000 the IDC began, and the prototype IDC stopped, distributing test products. There are currently 44 secure signatory accounts established with States Signatories to receive IMS data and IDC products.

The Global Communications Infrastructure

Global satellite coverage for the GCI was established in June 1999 with the commissioning of communications hubs to cover the Middle East and Europe, Atlantic Ocean, Indian Ocean and Pacific Ocean regions. Terrestrial links have been established to the independent sub-networks in a number of countries and very small aperture terminals (VSAT satellite dishes) have been established at about 20 National Data Centres for purposes of receiving IDC products. VSATs are being installed at IMS stations in States Signatories that have opted for the basic GCI topology, in coordination with the buildup of the stations; about 50 such VSATs are expected to be installed at IMS stations by the end of 2000.

Projected Status of IMS Stations at the End of 2001

Table 1 shows the projected status of the IMS stations at the end of 2001. This is based on the current draft of the 2001 Programme and Budget and assumes that the Preparatory Commission will approve this budget at its final meeting in November 2000. Overall, the figures suggest that by the end of 2001 96% of the site surveys will be completed, 56% of the stations will be installed and sending data to the IDC, and 41% of the stations will have been certified.