Technical Findings

The initial automatic detection of the event was made on 9 September 2016 at 00:30 UTC with 25 seismic stations contributing.  At first, the event was estimated at a magnitude of 5.0, slightly above the event that was detected on 6 January of this year. This was later revised by our analysts to 5.1, with data from over 100 stations contributing to the analysis. The location is very similar to that previous event.

The data was made available to Member States immediately, as were the results of the first automatic analysis that followed shortly thereafter and Member States were briefed on initial technical findings at 10:30 Vienna time during a meeting of the Preparatory Commission of the CTBTO.

Over the course of the coming days, the Revised Event Bulletin (the result of human analysis) will be made available to Member States.

Should traces of radioactivity have been released from the event, typically in the form of the radioactive noble gas xenon, they would need to be transported through the atmosphere to one of the radionuclide stations in the region, detected, sampled and analyzed. Results, if any, can be expected within days or weeks. After the 2013 announced nuclear test, xenon was detected around 55 days after the event.

Under the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the determination of an event's nature - nuclear explosion or not - lies with the Member States.