The shockwave from the Chelyabinsk meteor circled the Earth -- twice!

You know an explosion is powerful when an explosion requires a team of researchers who normally look for illicit nuclear bomb tests shift to study it. And yes, the group's results show that the Russian meteor created a big boom indeed.

Looking to understand more about the February 15 Chelyabinsk asteroid explosion, a research team led by Alexis Le Pichon studied data from the International Monitoring System (IMS) network operated by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO).

The abstract of their study, which now appears in Geophysical Letters, says it all:

On 15 February 2013, a large Earth-impacting fireball disintegrated over the Ural Mountains. This extraordinary event is, together with the 1908 Tunguska fireball, among the most energetic events ever instrumentally recorded. It generated infrasound returns, after circling the globe, at distances up to ~85,000 km, and was detected at 20 infrasonic stations of the global International Monitoring System (IMS). For the first time since the establishment of the IMS infrasound network, multiple arrivals involving waves that traveled twice round the globe have been clearly identified. A preliminary estimate of the explosive energy using empirical period-yield scaling relations gives a value of 460 kilotons of TNT equivalent. In the context of the future verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), this event provides a prominent milestone for studying in detail infrasound propagation around the globe for almost three days as well as for calibrating the performance of the IMS network.

Normally, their detection stations are on the look out for ultra-low frequency acoustic waves — also known as infrasound — that could come from nuclear test explosions. But in this case, the system detected the large blast produced by the Chelyabinsk fireball.