| The meteor over Russia entering the Earth’s atmosphere on 15 February 2013 around
03:20UT near the city of Chelyabinsk was the largest since the 1908 Tunguska fireball. As
such the shock waves generated by this event were observed at infrasonic stations globally, in
particular the network of some 45 of the planned 60 infrasound systems of the International
Monitoring System (IMS) being deployed for the verification of the Comprehensive Nuclear
Test-Ban Treaty (CTBT). Furthermore the shock waves coupling into the ground near the
source location were observed as Rayleigh waves at seismic stations to distances of more than
4000 km.
Beyond the acoustic observations that were made at infrasound sensors we report here on
additional observations of the acoustic waves which have coupled into the Earth at the
receiver. The corresponding observations were made in Central Europe, in particular at the
Gräfenberg broad-band array, as well as in Northern Europe (NORSAR in Scandinavia and
on Spitsbergen), where also broad-band seismic array stations are located. That indeed the
acoustic arrival from the bolide was recorded can be confirmed by frequency-wavenumber
analyses giving compatible velocities and back-azimuths for the ground-truth source location
over Russia. Theses observations are compatible with IMS station observations
and also with shock wave arrivals on seismic stations on the Eurasian platform. |