John on June 26, 2007
Was it a meteor? A comet? A UFO?!
Ever since a tremendous explosion (10-15 megatons) flattened trees and lit up the sky for thousands of miles, people have wondered what happened at Tunguska, Siberia back in 1908.
The site was investigated as early as 1927 (the photo above is from that first expedition), however no meteorite fragments were ever discovered. This mystery led to the suggestion that perhaps a comet, composed largely of ice, had exploded over the site, disintegrating in the process.
Today, a new investigation suggests the meteor which caused the explosion formed Lake Cheko about 8km Northwest of the explosion’s epicenter. Here’s a google image of the lake (click for dynamic map):
Lake Cheko is unusual in that it is nearly 50m deep. Other lakes in the area tend to be much shallower, suggesting it wasn’t formed by usual processes. The study which has just been published in Terra Nova also notes the lack of information on the lake prior to 1908:
Previous information on Lake Cheko was limited to few soundings and sediment samples collected in 1960. However, as the region is remote and uninhabited, there is no reliable evidence even on whether or not the lake existed before 1908. In fact, the presence of the lake was not reported in maps drafted before 1928 and is not mentioned by eyewitness testimonies.
Maybe it just wasn’t there. But here’s the really cool part:
A prominent reflector observed in seismic reflection profiles 10 m below the bottom at the center of the lake indicates a sharp density/velocity contrast, compatible with either the presence of a fragment of the body, or of material compacted by the impact. Drilling could solve this dilemma.
In other words, there’s something hard down there, possibly the meteorite that caused the Tunguska event. Let’s start excavating now! We’ll need a pretty big crane as this thing could weigh as much as 1,700 tons.
And because this was so interesting I made a little Google map of other craters around the world.