Update on CTBTO findings related to the announced nuclear test by North Korea

By 14 February 2013, 96 International Monitoring Stations have sent data related to the announced North Korean test (click to enlarge)

Vienna, 15 February 2013

A total of 96 International Monitoring System (IMS) stations have now sent data related to the unusual seismic activity detected in North Korea on 12 February 2013 to the International Data Centre (IDC) in Vienna for analysis. The magnitude of the event has been confirmed as 4.9 by the IDC. The analysed data have also enabled the error ellipse to be decreased, thus confirming the event’s location with a certainty of about +/- 8.1 km.

In-depth analysis of data sent to Member States the following day

At a meeting for Member States today, Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) Executive Secretary Tibor Tóth, IDC Director Lassina Zerbo and other scientific experts updated delegates on the organization’s latest findings. In the three days since the Democratic People’s Republic of Korea (DPRK) announced that it had conducted its third nuclear test, experts at the IDC in Vienna have been analysing a vast amount of data generated by the IMS. By around 17:00 (UTC) the following day, Member States had already received the Reviewed Event Bulletin (REB) containing a careful analysis of the data. The timeframe specified in the Comprehensive Nuclear-Test-Ban Treaty (CTBT) for distribution of the REB is specified as 48 hours after the end of the day on which the event took place -  so analysts worked around the clock to ensure that it was sent out so quickly.

International denouncement of DPRK’s declared nuclear test

The DPRK’s declaration that it had conducted a successful nuclear test has received universal condemnation. Members of the UN Security Council held urgent consultations to address the situation, which they described as ‘a grave violation of Security Council resolution 1718(2006), 1874(2009) and 2087(2013) and a clear threat to international peace and security’. Several high-level political figures tweeted on the CTBTO’s initial findings, including Swedish Foreign Minister Carl Bildt and U.S. Department of State's Assistant Secretary for Arms Control, Verification, and Compliance, Rose Gottemoeller. Click here for more international reactions.

Constantly monitoring the globe for evidence of a nuclear explosion

The CTBTO uses four verification technologies to ensure that no nuclear explosion goes undetected. Seismic sensors record shockwaves in the ground caused by underground nuclear explosions while hydroacoustic and infrasound stations monitor the oceans and atmosphere respectively. Radionuclide stations monitor the atmosphere for radioactive particles or noble gases which may escape from an underground nuclear explosion. Assuming that there is a release of radionuclides, it could take several weeks before they are detected. For example, a CTBTO radionuclide station in Yellowknife, Canada, detected the radioactive noble gas xenon 133 two weeks after the 2006 DPRK nuclear test but no radionuclides were detected following the 2009 test. A technique called Atmospheric Transport Modelling will be used if such radionuclides are detected to backtrack the emissions from the radionuclide station to determine the source.

Increased number of stations in operation allows for greater detection accuracy

Comparison of the location estimates of the 2006 (green), 2009 (violet), and 2013 (red) announced nuclear tests by North Korea (click to enlarge)

The 2006 DPRK nuclear test was detected by 22 IMS stations, the 2009 test by 61, and the 2013 test by 96. This increase was due to the rise in the number of stations in operation as well as the larger magnitude of the 2013 test. Between 2009 and February 2013, the number of CTBTO seismic stations has further increased from 130 to 160. This increase has enabled the CTBTO to locate the event with more precision. In 2006, the event was estimated to have taken place within an area of 880km2,in 2009, the location was narrowed down to 265km2 and in 2013 the CTBTO has located the event within an area of 181km2. In total, over 85 percent of the CTBTO’s 337 monitoring facilities are now up and running; see interactive map. Once the Treaty has entered into force, an on-site inspection can be invoked in case of a suspicious event. This final verification measure will determine whether or not a nuclear explosion has been conducted.

Addition - 12 March 2013

No radioactive noble gases attributable to the 12 February event have been detected by CTBTO radionuclide stations so far. While an on-site inspection could still potentially locate evidence of a nuclear explosion, this option will only become available after the CTBT's entry into force.