Tunguska

Tunguska (Тунгуска) is a remote, largely uninhabited region in Siberia, Russia, near a river of the same name. It is known for an enormous impact event 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.