Tunguska River
Siberia, Russia. It is known for an enormous impact event near the Stony (Podkamennaya) Tunguska River at about 7:17 AM local time, on the morning of June 30, 1908, which felled an estimated 60 million trees over 2,150 square kilometres but did not leave a crater. The impact was felt as far away as 1,000 kilometres. At 500 kilometres, witnesses had claimed to have heard a 'deafening bang' and a cloud on the horizon. The size of the blast is said to have been the equivalent of between 10 and 15 megatons of TNT. The likeliest explanation is that it was caused by the impact of a small comet, although numerous theories about UFOs and other phenomena have been suggested; for more details, see the article on the Tunguska event.
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