Most estimates are a little bigger, around 20kt. That's why the use of megatons in that article boggled my mind. Might be that their "science editor" doesn't know his prefixes or thinks that "megaton" is just for coolness factor, but since it is based on seismic data I'm wanting to look into it. I'd never heard of a seismic estimate for the event, only blast pattern based ones.

The best estimates for the yield are between 12 and 20 Megatons. This estimate was done purely from the blast radius of about 20-25 Km together with the blast pattern. The object that impacted at Tunguska is still a mystery, simply because of the lack of any crater and little physical remains which were left from the object which impacted, hence theories such as antimatter and microscopic singularities. The altitude of the explosion is calculated from the atmospheric over pressure and the amount of energy coupling with the ground. i.e. the seismic recordings. There was also very little particle radiation from nuclear fallout at the Tunguska site.

The eye witness reports are very interesting indeed, they describe what would be the equivalent of an air burst thermonuclear detonation. i.e. Descriptions of a blinding blueish light from another sun then of the sky splitting in two. Even descriptions of a central swirling cloud moving upwards are reminiscent of an air burst thermonuclear explosion. A purely thermonuclear reaction would have only given a huge neutron burst (mostly absorbed to form carbon isotopes for example and little to no heavy isotope particle radiation).

The most likely candidate for the object which struck the Tunguska site would be a small comet. This theory also has problems due to the lack of a crater. I would be inclined to go along the lines of something quite small (a ball of Deuterium and Tritium plasma weighing only Kgs), traveling at relativistic velocities emanating from the sun or near the sun (ejected from the suns chromosphere possibly), which could generate the above 150 million degree heat needed for a thermonuclear reaction when it impacted the upper atmosphere above Tunguska.

Just saw this over at fox news,

http://www.foxnews.com/story/0,2933,286807,00.html

Not all of humanity is equal. The atrocities of the Soviet regime speak for themselves.

-Blast, taking a drink

I'm gonna become a lush reading some of these posts...

They might come in handy when the next asteroid or comet comes winging it's way through our cosmic neighborhood.

I am going to chase this mucky yucky stuff with a beer, as soon as I hit the beach.

Arrrrgggghghhhhh!!!!!!!!!!!!!!

I think you just watched Dr. Strangelove and took it a bit too seriously.

"I can no longer sit back and allow PHRASECENSOREDPOSTERSHOULDKNOWBETTER. infiltration, PHRASECENSOREDPOSTERSHOULDKNOWBETTER. indoctrination, PHRASECENSOREDPOSTERSHOULDKNOWBETTER. subversion and the international PHRASECENSOREDPOSTERSHOULDKNOWBETTER. conspiracy to sap and impurify all of our precious bodily fluids."

They think if the collision had occurred only 4 hours 47 minutes later, it would have wiped out St. Petersburg, due to the rotation of the Earth.

The Fog of War