The mysterious Tunguska event, the largest known impact event on Earth in recorded history, was triggered by the explosion in mid-air of a superbolide near the Stony Tunguska River on 30 June, 1908.
The cataclysmic explosion of the giant 60 to 190 metres (200 to 620 feet) space object, occurred at an altitude of 5 to 10 kilometres (3 to 6 miles). It flattened an incredible 2,000 km2 (770 sq mi) of forest. Nobody was killed.
Since the 1908 event, there have been an estimated 1,000 scholarly papers. Some samples from a peat bog near the centre of the affected area show fragments that may be of meteoritic origin (asteroid or comet).
Early estimates of the energy of the air burst range from 10–15 megatons of TNT (42–63 PJ), to 30 megatons of TNT (130 PJ). In contrast, modern supercomputer calculations estimate that the airburst had an energy range from 3 to 5 megatons of TNT (13 to 21 PJ).
In both cases, it is just insane!
The 15 megaton estimate is an energy:
- About 1,000 times greater than that of the atomic bomb dropped on Hiroshima, Japan;
- Roughly equal to that of the United States’ Castle Bravo (15.2 Mt) thermonuclear test detonation on 1 March 1954;
- About one-third that of the Soviet Union’s later Tsar Bomba (at 50 Mt was the largest nuclear weapon ever detonated).
It is estimated that the Tunguska explosion knocked down some 80 million trees over an area of 2,150 square kilometres (830 sq mi).
The shock wave from the blast would have measured 5.0 on the Richter magnitude scale.
An explosion of this magnitude would be capable of destroying a large metropolitan area, but due to the remoteness of the location, no fatalities were documented.
This event has helped to spark discussion of asteroid impact avoidance.