Mysterious Lake Baikal Ice Circles Visible On Google Maps!
In a recent Wired article, I read about a circular region of melted ice that ISS astronauts spotted from space in a Siberian lake. It's almost certainly caused by some upwelling of heat from the Earth's crust, however no one really knows what's going on. For grins, I went and checked out the Google Maps sat view of the region and it's not during the winter. Instead, it shows lots of dark blue water. But when I took a screenshot and ran it through The Gimp's "Colors -> Auto -> Equalize" filter, I got the picture to the right, showing that the region appears in a slightly different color, even when the ice is melted! This is probably due to differences in dissolved gasses or salinity caused by the heat, but I'm no geologist, so I'm not sure. It's just interesting that Google Maps has had this data all along and no one knew.
You'll notice a region to the lower right that is a very different color of blue. It looks like this is a seam between two different sources of images. That's where a more detailed set of (probably aerial) photos begin. The main region is a lower-rez and probably older set of photos that I believe were from the original satellite images that Google Maps began with.
Update 2009-05-27: Similar features can be seen around the northern circle that was identified in the Wired article, when using the Google Maps images.
However, much more telling is the fact that the location pictured above was the epicenter of a magnitude 6.2 earthquake late last year. I think that makes it fairly likely that this is a geothermally active area and that the circles could indicate escaping gasses or related events.
http://essays.ajs.com/2009/05/myster...e-circles.html