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Details Emerging On Tunguska Impact Crater
#space_on_irc.freenode.net (Dusty) writes "Lake Cheko in Siberia has been noted as the probable crater of the 1908 Siberian Tunguska event. This news was discussed here in December, but details on the crater were scant. Now a new paper written by Luca Gasperini, Enrico Bonatti, and Giuseppe Longo (the same team in Bologna, Italy that made news in December) has a horde of new details on the supposed crater. The team visited Lake Cheko complete with their own catamaran and completed ground-penetrating radar maps, side-scanning sonar images, aerial images, and some sample collection of Lake Cheko. Intriguingly, they also imaged an object under the sediment that may be a fragment of the impacting body. Their paper (PDF) includes a lot more details including images, side-scanning sonar image, a 3-D view of the lake, a morphobathymetric map. It's an interesting read, these dudes are good. They plan to return this summer and drill the core if weather permits, hopefully answering the question once and for all." The same team also has a more discursive article in the current Scientific American that includes some detail on the working conditions in the Siberian summer. Think: mosquitos.
err, post I mean
"The first time I got drunk, I got married. The second time I bought a chimpanzee, after that I stayed sober" Arian Seid
The team visited Lake Cheko complete with their own catamaran
Is it really that hard to spell 'cameraman' correctly? C'mon editors! Get on it!
Seriously, the smart bet seems to be that event was caused by an asteroid strike. But until someone gathers some hard data, that's still only a hypothesis.
What self respecting scientist wouldn't go and examine the evidence? Because if it wasn't an asteroid strike...
Don't let THEM immanentize the Eschaton!
The paper in the posting is a reply to a comment with the contrary interpretation (i.e. that Lake Cheko isn't an impact) [Same paper as PDF]. The critical comment should be cited too.
The original paper by Gasperini et al. (2007) is also available as PDF and HTML.
I'm not particularly convinced by the evidence they present. It's quite circumstantial. What they need to find and sample is an ejecta-related layer in the lake stratigraphy or in a lake nearby, and you'd think that if such a large impactor hit the ground there would be plenty of micrometeorite debris in the sediments of the surrounding area. Geomorphological evidence and age just isn't enough.
1 Our sub-bottom acoustic reïection data show that, of a 10 m thick sediment pile, only the top
1 ± 0.5 m is laminated, ïne-grained, normal lacustrine sediments (Gasperini et al., 2007). The
lower chaotic material appears not to be deposited by normal lacustrine sedimentation.
2 210 Pb and 137 Cs datings on sediment cores from the lake suggest sedimentation rates of roughly 1cm/yr)1(Gasperini et al., 2001). Assuming this rate is mostly due to ïne-grained material transported into the lake from the Kimchu
River, the thin lacustrine sequence is compatible with a young (100 years) age for the lake.
Or Google Maps Even
http://maps.google.com/maps?f=q&hl=en&geocode=&q=60.964,+101.86&ie=UTF8&ll=60.963631,101.859055&spn=0.010102,0.016522&t=h&z=16
True, a nuclear weapon will leave radioactivity and this can be detected readily. Unfortunately we are still living in a world where submarines, bombers and missiles are pointed from country to country like loaded shotguns on a hair trigger.
My fear is that someone would mis-interpret an incoming meteor as a nuclear weapon and initiate a launch on their perceived threats.
If Moscow, Washington DC, Beijing or London were wiped out in a meteorite strike that was not detected before the destruction. Do you think that missile forces would not be put on high alert?
We are not that far away from the days of "Fail Safe".
Tisha Hayes
From the SciAm article's photo caption: "In this artist's conception, Semen Semenov, who witnessed the blast at a distant trading post, starts to feel the heat."
That's... a really, really unfortunate name, dude.
(I love that they managed to work "heat" and "conception" into a sentence about a guy named Semen.)
I'm only wearing black until they come out with something darker.
The grandparent may be thinking of this event. Had the bollide arrived a few hours earlier, it would have exploded over either Pakistan or India who were already shooting at each other over Kashmir. The explosion was twice as large as the Hiroshima blast.
Whether both sides would have held their fire in that event is hard to tell.