Simulation of the airwave caused by the Chelyabinsk superbolide

Abstract

Numerical simulations were carried out to model the propagation of an airwave from the fireball that passed over Chelyabinsk (Russia) on 15 February 2013. The airburst of the Chelyabinsk meteoroid occurred due to its catastrophic fragmentation in the atmosphere. Simulations of the space-time distribution of energy deposition during the airburst were done using a novel fragmentation model based on dimensionality considerations and analogy to the fission chain reaction in fissile materials. To get an estimate of the airburst energy, observed values of the airwave arrival times to different populated localities were retrieved from video records available on the Internet. The calculated arrival times agree well with the observed values for all the localities. Energy deposition in the atmosphere obtained from observations of the airwave arrival times was found to be 460 ± 60 kt in trinitrotoluene (TNT) equivalent. We also obtained an independent estimate for the deposited energy, 450+200-160 kt TNT from detecting the air increment velocity due to the wave passage in Chelyabinsk. Assuming that the energy of about 90 kt TNT was irradiated in the form of visible light and infrared radiation, as registered with optical sensors [Yeomans and Chodas, 2013], one can value the total energy release to be about 550 kt TNT which is in agreement with previous estimates from infrasound registration and from optical sensors data. The overpressure amplitude and its positive phase duration in the airwave that reached the city of Chelyabinsk were calculated to be about 2 kPa and 10 s accordingly.