Scientists invited to participate
in International Scientific Studies project

The International Scientific Studies project invites scientists to participate in an evaluation of the Comprehensive Nuclear-Test-Ban Treaty’s verification regime.

Overall objective

Operations Centre at the International Data Centre, Vienna, Austria.

The International Scientific Studies project (ISS) will evaluate the verification regime of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) through a series of scientific studies and assessments, which will address the readiness and capability of the CTBT to detect nuclear explosions worldwide.

Promoting global participation

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is the facilitator and coordinator of the project but will not be performing the evaluation. This will be the task of the international scientists and institutions participating in the project. Some sponsors have made funding available through voluntary contributions, which could be used to promote global participation in this project, especially experts and institutions from developing countries.

Performance of the verification regime

The studies and assessments will highlight progress made in seismology, hydroacoustics, infrasound and radionuclide monitoring over the last ten years. These are the four technologies used by the 337 facilities comprising the CTBT’s International Monitoring System (IMS) to monitor the Earth for evidence of nuclear explosions. The performance of the CTBT’s global verification system and its ability to detect and locate observed events will be examined. In the CTBT context, an “event” is any physical occurrence that is registered by the IMS, be it a natural or a man made event, an earthquake or an explosion, a chemical or a nuclear explosion. An evaluation will also be made of the timeliness, quality and quantity of data which are produced, transmitted, processed and distributed to Member States by the International Data Centre (IDC) in Vienna, Austria.

Click here for more information about the verification regime.


The nearly 30,000 seismic events registered in 2006.

The seismic network is made up of 50 primary stations which send their data in real time to the IDC, and 120 auxiliary stations that make their data available upon request from the IDC. Seismic data are used to locate seismic events and to distinguish between an underground nuclear explosion and the numerous earthquakes that occur around the globe.

The study will focus on understanding and increasing the capability of the network to detect and locate seismic events globally. It will also explore ways in which seismic information can be used more fully to characterize events. For more information about seismology visit the seismic monitoring section.


Setup of hydroacoustic station cable at Crozet Island, France.

The hydroacoustic network comprises six "hydrophone" stations and five "T-phase" (seismic) stations. Hydrophone stations use underwater microphones to capture signals underwater and then transmit them via cable to the shore station. T-phase stations are located on oceanic islands and use seismometers to detect the acoustic waves that are converted to seismic waves when they hit the island. The data from these stations are used to distinguish between underwater explosions and other phenomena, such as sub-sea volcanoes and earthquakes, which also propagate acoustic energy into the oceans. The study will evaluate the network’s coverage and its ability to detect and locate events. For more information about hydroacoustics visit the hydroacoustic monitoring section.


Infrasound station at Qaanaaq, Greenland.

The infrasound network of 60 stations uses microbarographs (acoustic pressure sensors) to detect very low-frequency sound waves in the atmosphere produced by natural and man-made events. The data are used by the IDC to locate and distinguish between atmospheric explosions and natural phenomena such as meteorites, explosive volcanoes and meteorological events and man-made phenomena such as re-entering space debris, rocket launches and supersonic aircraft. Estimates will be made of the detection and location capabilities of the infrasound network at regional and global distances. The study will explore ways of improving these capabilities and enhance understanding about how waves propagate through the atmosphere. For more information about infrasound visit the infrasound monitoring section.

Radionuclide observations

Radionuclide Station RN33, Schauinsland, Germany.

The radionuclide network consists of 80 stations which use air samplers to detect radioactive particles released from atmospheric nuclear explosions and those vented from underground or under water explosions. The relative abundance of different radionuclides in these samples means that materials produced by a nuclear reactor can be distinguished from those of a nuclear explosion. The network’s 16 radionuclide laboratories are used to make a more thorough analysis of samples containing radionuclide materials that may have been produced by a nuclear explosion. Half of the stations in the radionuclide network also have the capacity to detect xenon, a radioactive noble gas. The presence of radioactive noble gases can indicate whether a nuclear explosion has taken place and noble gases might escape even if an explosion is conducted underground. For more information about radionuclide monitoring click here.

A thorough assessment of the performance of radionuclide particles and noble gas monitoring networks will be conducted during the study. Data will also be compiled on those radionuclides that are a result of human activity and those that occur naturally.

Atmospheric Transport Modelling

Atmospheric Transport Modelling (ATM) estimates the ways that radioactive particles are carried through the air. It is an integral part of CTBT verification procedures as it enables the sources of radionuclide particles and noble gas observations to be located. The study will aim to estimate the capabilities of current ATM procedures and explore ways of further improving their accuracy.

On-Site Inspection (OSI)

Experts test electrical conductivity measurements at a training course in Hungary in October 2007.

An on-site inspection (OSI) can be requested by a Member State to clarify whether a nuclear explosion has been carried out in violation of the Treaty and to gather any information which might assist in identifying the potential violator.

Various techniques can be used to conduct an OSI. These include: position finding, overflights, visual observation, video and still photography, multi-spectral imaging (including infrared measurements) and gamma radiation monitoring. Environmental sampling and analysis, passive seismological monitoring for aftershocks, resonance seismometry and active seismic surveys, magnetic and gravitational field mapping, ground penetrating radar, electrical conductivity measurements, and drilling may also be used in the event of an OSI.  Noble gases such as xenon and argon will be measured on-site. The evaluation will examine the effectiveness and limitations of the OSI inspection techniques and assess how recent scientific and technical advances can be applied to an OSI. For more information visit the on-site inspection area.

Data mining

There have been significant developments in modern IT-based analysis methods known as “data mining” over the last decade. The study will determine whether such methods can be applied to the analysis of data in all stages of station and network processing as well as in event categorization.

Importance of involvement by the scientific community in the evaluation

The ISS is the most comprehensive assessment of the CTBT’s verification capabilities ever conducted. It will play a key role in determining how science has evolved since the CTBT was negotiated between 1994-96. The technical complexity and global reach of the monitoring system has presented engineering challenges unprecedented in the history of arms control. So far, 254 IMS facilities have been installed, with many of them located in remote and inaccessible parts of the globe. While there have been significant developments and progress in the establishment of the verification regime over the last ten years, involvement by the scientific community in this evaluation is of crucial importance to determine the capabilities of the system and how the system can be further improved within the framework of the Treaty.

Participants and project schedule

The project was launched in Vienna in March 2008 and attended by approximately 100 scientists from 33 countries.  It is open to experts and institutions from around the world. The evaluation will take place over the next year, culminating in a final report highlighting the key findings to be presented at a large scientific conference in Vienna in June 2009. There will also be a two-day workshop in Vienna from September 15-16 2008 to discuss data fusion and data mining.

For further reading about the ISS project, you can order a copy of our brochure by emailing us at You can also download the PDF brochure by clicking on the following link.

You can also download the ISS planning phase (PDF) report and view the press release.

Contact information

If you would like to participate in the International Scientific Studies project or you require more information, please email (for scientists and scientific institutions) or (for general information)