Characterizing The Chelyabinsk Airburst : Implications For The Impact Hazard

At 03:20 UT (09:20 local time) on Feb 15, 2013 a bright, long-lasting fireball was widely observed over the region of Chelyabinsk, Russia. Eyewitness reports extend out to more than 700 km.

This event was of such large energy that the shock wave reaching the surface had sufficient overpressure to blow out windows, doors and cause light structural damage particularly in the region to the South of Chelyabinsk, as well as in the city of Chelyabinsk. According to Russian media reports, close to 1500 people were injured by flying debris (mainly broken windows) as a result of the shock wave. The energy of the event has been estimated from several independent techniques to be approximately 500 kT of TNT equivalent. The airwave from the airburst was recorded by infrasound sensors over the entire globe; some records show several revolutions of the planet (including antipodal returns) some 24 hours after the event. The range of energy yields translates into a meteoroid with a mass of order 12 000 tonnes and diameter of approximately 19m. This fireball is the most energetic confirmed airburst since the Tunguska fireball of 1908. Chelyabinsk’s energy, fragmentation and trajectory are well constrained – together with measurements of the associated surface blast effects it provides an important baseline for interpretation of future impactors and past events such as Tunguska.