Tunguska – The Most Powerful Explosion by an Astronomical Object in Modern Times
January 31, 2013
The most powerful natural explosion in recent Earth history occurred on 1908 June 30 when an astronomical object exploded above the Tunguska River in Siberia, Russia. About 2150 square kilometres of Siberian taiga were devastated and 80 millions trees were overthrown. The explosion is believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3–6 mi) above the Earth’s surface. Different studies have yielded widely varying estimates of the object’s size, on the order of 100 metres (330 ft). It is the largest impact event on or near Earth in Modern Times.
Estimates of the energy of the blast range from 5 to as high as 30 megatons of TNT with 10–15 megatons of TNT the most likely — roughly equal to the United States’ Castle Bravo thermonuclear bomb tested on March 1, 1954; about 1,000 times more powerful than the atomic bomb dropped on Hiroshima, Japan; and about two-fifths the power of the later Soviet Union’s own Tsar Bomba, the largest nuclear weapon ever detonated. An explosion of this magnitude is capable of destroying a large metropolitan area. This possibility has helped to spark discussion of asteroid deflection strategies.
Here’s a Dynamic map of the Tunguska Ground Zer Area:
2 Eyewitness reports:
At around 7:17 a.m. local time, witnesses settlers in the hills northwest of Lake Baikal observed a column of bluish light, nearly as bright as the Sun, moving across the sky. About 10 minutes later, there was a flash and a sound similar to artillery fire. Eyewitnesses closer to the explosion reported the sound source moving east to north. The sounds were accompanied by a shock wave that knocked people off their feet and broke windows hundreds of kilometres away. The majority of witnesses reported only the sounds and the tremors; not the sighting of the explosion.
Asteroid or comet:
In 2010, an expedition of Vladimir Alexeev, with scientists from the Troitsk Innovation and Nuclear Research Institute (TRINITY), used ground penetrating radar to examine the Suslov crater at the Tunguska site. What they found was that the crater was created by the violent impact of a celestial body. The layers of the crater consisted of modern permafrost on top, older damaged layers underneath and finally, deep below, fragments of the celestial body were discovered. Preliminary analysis showed that it was a huge piece of ice that shattered on impact, which seem to support the theory that a comet caused the cataclysm.
In June 2007, scientists from the University of Bologna led by professor Giuseppe Longo identified a lake in the Tunguska region as a possible impact crater from the event. They do not dispute that the Tunguska body exploded in midair but believe that a one-meter fragment survived the explosion and struck the ground. Pollen analysis reveals that remains of aquatic plants are abundant in the top post-1908 sequence but are absent in the lower pre-1908 portion of the core. These results, including organic C, N and δ13C data, suggest that Lake Cheko formed at the time of the Tunguska Event.