The Tunguska Event was a massive explosion that occurred near the Podkamennaya (Lower Stony) Tunguska River in what is now Krasnoyarsk Krai of Russia, at around 7:14 a.m. (0:14 UT, 7:02 a.m. local solar time) on June 30, 1908 (June 17 in the Julian calendar, in use locally at the time). Estimates of the energy of the blast range from 5 megatons to as high as 30 megatons of TNT, with 10–15 megatons the most likely - roughly equal to the United States' Castle Bravo thermonuclear explosion set off in late February of 1954, about 1000 times more powerful as the bomb dropped on Hiroshima, Japan and about one third the power of the Tsar Bomba, the largest nuclear weapon ever detonated. The explosion knocked over an estimated 80 million trees over 2,150 square kilometers (830 square miles). It is estimated that the earthquake from the blast would have measured 5.0 on the Richter scale, which was not yet developed at the time. An explosion of this magnitude is capable of destroying a large metropolitan area.
Although the cause is the subject of some debate, the explosion was most likely caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3–6 miles) above Earth's surface. Different studies have yielded varying estimates for the object's size, with general agreement that it was a few tens of meters across.
Although the Tunguska event is believed to be the largest impact event on land in Earth's recent history, impacts of similar size in remote ocean areas would have gone unnoticed before the advent of global satellite monitoring in the 1960s and 1970s.
- Height 611 UFO incident - an alleged UFO crash in far-east Russia which left similar traces in the environment.
Game and Story Use
- Various UFO aficionados have claimed that the Tunguska event was the result of an exploding alien spaceship or even an alien weapon going off to "save the Earth from an imminent threat". In a world where this is true this would demonstrate both the horrific scope of alien capabilities and how effective and old the big cover-up really is.
- If instead the event was a use of human technology, then a powerful secret group with access to technology at least decades ahead of its time must have existed. In that case, it or some other powerful secret organization with technology decades ahead may still exist today.
- It may have been a use of Nikola Tesla's death ray technology. Spider Robinson used this idea in the novel Callahan's Key.
- Seismologists have determined that an explosion more powerful than any known WMD has occurred deep inside enemy territory. The enemy insists that it is due to a meteor strike rather than a weapon test, but your government needs to know for sure.
- Every good fantasy setting should have some sort of meteorite impact now and then - especially if it leaves some strange material behind that can be used by adventurers. From "star metal" that's devastating to the fey to a magic-rich but highly mutagenic substance (such as the Warpstone of Warhammer fame), the possibilities are endless.
- If time travel exists, the Tunguska event may be the result of a massive intervention. This would clearly demonstrate the lengths to which the group that carried out the intervention is willing to go.
- Since recorded history doesn't show anything interesting being at the site before the explosion, it would be interesting to wonder what was achieved by such an intervention. A party may be sent to investigate the area before the explosion takes place.