||Seismic Observations of the Sonic Boom Produced by the Chebarkul Meteorite
YAMADA, MasumiMORI, James
京都大学防災研究所年報. B = Disaster Prevention Research Institute Annuals. B
52 , 2015-06 , 京都大学防災研究所
The Chebarkul meteorite entered Earth's atmosphere over Russia on 3:20 February 15, 2013 (UTC) producing a strong sonic boom throughout Chelyabinsk Oblast. A seismic signal was observed at the same time in the broadband seismic data of the IRIS network. We performed a waveform inversion using 5 broadband seismic records to obtain the source-time function of the Chebarkul meteorite signal. Assuming a single force for the source mechanism, the waveform can be explained well with a point source model. We performed a grid search in space to find the location of the source. The best-fit source location was determined on the meteor track and 40km away from lake Chebarkul, where the large hole from the impact was detected after the meteor fall. We use the modified Friedlander equation to estimate a deconvolved form of the source time function, and the amplitude of the estimated single force is 2.0 *10e11 N and the onset of the pulse is at 3:21:58 (UTC), February 15, 2013. Since the location of the estimated source is separated from the impact point, the single force generating the seismic waves was produced by the blast wave due to the severe fragmentation of the bolide, not the impact of the meteorite on the ground.