The Tunguska Event was a powerful explosion that occurred near the Podkamennaya Tunguska River in Siberia, Russia on June 30, 1908. The explosion is believed to have been caused by an air burst of a large meteoroid or comet fragment, estimated to have
From Wikipedia
The Tunguska event was a large explosion of between 3–50 megatons TNT equivalent that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate, Russia, on the morning of 30 June [O.S. 17 June] 1908.