Tunguska Impact Crater Found?

BigBadBus writes in with a claim by an Italian team that they may have found an impact crater resulting from the 1908 Tunguska explosion over Siberia. The BBC story quotes a number of impact experts who doubt the Italians' claim. "A University of Bologna team says a lake near the epicenter of the blast may be occupying a crater hollowed out by a chunk of rock that hit the ground. Lake Cheko — though shallow — fits the proportions of a small, bowl-shaped impact crater, say the Italy-based scientists. Their investigation of the lake bottom's geology reveals a funnel-like shape not seen in neighboring lakes. In addition, a geophysics survey of the lake bed has turned up an unusual feature about 10m down which could either be compacted lake sediments or a buried fragment of space rock."

Google Maps

[eldavojohn]

Areal view of what was believed to be the original impact site [google.com] and Lake Cheko [google.com].

I'm no geologist so I can't comment on whether or not this lake looks typical but I will say that, judging by the coloration of the foliage around it, this is probable the same land as the river/stream that winds to the west of it. Interesting is that if you follow it northwest for miles it looks smooth cut. Once it passes Lake Cheko, it seems to become more speckled and pock marked. Doesn't seem 'natural' to me for an inlet and outlet to be positioned so close together on a lake--though the topography could indeed make that make sense if I could see a map of it.

I would guess this is quite feasible indeed to be part of whatever happened nearly 100 years ago. Check out the last page of this PDF [aero.org] which seems to show the comet/asteroid approaching at an angle (thus the strange blast pattern). At that trajectory, you'd think there'd be a chance for whatever hit to break apart and skip. Maybe the other abnormal marks in the stream are from other pieces/debris?

Probably fueled by the sci-fi stories written about the same topic (like the 1946 one by Alexander Kazantsev), I find it interesting to read about things like the Tunguska Genetic Anomaly [arxiv.org] whether they be true or not. Maybe these are the scientist's tabloids? :)

Shouldn't this be easy to prove?

[pclminion]

If this is in fact the real impact site, shouldn't there be elevated iridium levels in the lake sediments, as is usually found at other impact sites? I guess "prove" is too strong a term, but I'd challenge anyone to find an alternate explanation for elevated iridium, if found.

what would we find here

[wizardforce]

Now what would we find at this site if it were the tunguska impact crater? since it was likely mostly ice/volatiles mixed with some rocky material would it be fair to say that we wouldnt be finding evidence of shok metamorphosis when the volatiles likely carried off most of the heat? for that matter, would there even be a single crater when the original object shattered as it did? wouldnt it be likely that several small impacts form and over the years erode?

Well

[Bandman]

Shocked quartz could solve the matter once and for all.

Trees standing near the impact site aren't that big of an anomaly, although they do point to an airborne explosion. IIRC some of the witnesses reported that there were standing trees, and modeling of the event (as well as other powerful explosions which occurred at an altitude) have left standing trees, edifaces, and so on, directly below the force of explosion.

Personally, I'm still hoping for Tesla's Death Ray

55 Fiction

[Carthag]

In the far reaches of the Siberian tundra, the shaman sits naked. To his left, the head of a freshly slain hare, to his right, a small bundle of herbs. As he calls out in the old language that he is the last to know, the sky lights up like a thousand suns.

Tunguska remembers.

Hah! Everyone knows it wasnt a meteorite...

[Tmack]

It was a quantum black hole [wikipedia.org] passing through the earth!

The most they will ever find is a nano sized cave where it traveled through the earth at near-light speed before going about its way after popping out through an ocean on the other side....

tm

What about Tesla

[Anonymous Coward]

No one ever will find an impact crater, because Nikola Tesla did it [wikipedia.org]

Finally a good science quote

[cvd6262]

I'm so tired of hearing "researchers" talk about the certainties of their discoveries. This is a breath of fresh air:

"We have no positive proof this is an impact crater, but we were able to exclude some other hypotheses, and this led us to our conclusion," Professor Longo, the research team leader, told BBC News.

Re:Google Maps

[Anonymous Coward]

There are similar lakes, albeit much smaller, just to the northwest [google.com] and to the east [google.com] along the same river. They look like flooded meander [wikipedia.org] cutoffs [wikipedia.org] to me. The outer edge of the lake opposite the river entry and exit (i.e. the N, E, and S sides) would fit the shape of a former stream channel with the same kind of sinuosity as the rest of the river.

The mundane explanation looks far more likely than the exotic one, and where's the crater rim?? It's entirely absent. Why is the lake elliptical? As the article mentions, it takes a very low angle impact to yield an elliptical crater.

Also from the article:

"Intriguingly, Lake Cheko does not appear on any maps before 1929, though the researchers admit the region was poorly charted before this time."

It's on a river floodplain (although the river doesn't look especially active). If it is a meander cutoff, it might have formed subsequent to the maps. More interesting would be to sample sediment cores from local lakes that *are* on pre-1929 maps, and see if there is a meteoritic dust layer from the 1929 event.

This "crater" looks completely unconvincing. I can't believe they managed to get this claim published in Terra Nova or any other journal.

Re:Impact, eh?

[PoliTech]

You may have been joking AC (Pun Intended), but the "Tesla Death Ray" has been suggested as one of the possible causes of the Tunguska event for many many years.

Here is an About.com article that talks about it more. http://paranormal.about.com/cs/earthmysteries/a/aa 021604.htm [about.com]

The text below is lifted from this site: http://prometheus.al.ru/english/phisik/onichelson/ tunguska.htm [prometheus.al.ru]

The Tunguska event took place on the morning of June 30th, 1908. An explosion estimated to be equivalent to 10-15 megatons of TNT flattened 500,000 acres of pine forest near the Stony Tunguska River in central Siberia. Whole herds of reindeer were destroyed. Several nomadic villages were reported to have vanished. The explosion was heard over a radius of 620 miles. When an expedition was made to the area in 1927 to find evidence of the meteorite presumed to have caused the blast, no impact crater was found. When the ground was drilled for pieces of nickel, iron, or stone, the main constituents of meteorites, none were found down to a depth of 118 feet.

Several explanations have been given for the Tunguska event. The officially accepted version is that a 100,000 ton fragment of Encke's Comet, composed mainly of dust and ice, entered the atmosphere at 62,000 mph, heated up, and exploded over the earth's surface creating a fireball and shock wave but no crater. Alternative explanations of the disaster include a renegade mini-black hole or an alien space ship crashing into the earth with the resulting release of energy.

Associating Tesla with the Tunguska event comes close to putting the inventor's power transmission idea in the same speculative category as ancient astronauts. However, historical facts point to the possibility that this event was caused by a test firing of Tesla's energy weapon.

In 1907 and 1908, Tesla wrote about the destructive effects of his energy transmitter. His Wardenclyffe facility was much larger than the Colorado Springs device that destroyed the power station's generator. Then, in 1915, he stated bluntly:

It is perfectly practical to transmit electrical energy without wires and produce destructive effects at a distance. I have already constructed a wireless transmitter which makes this possible. ... But when unavoidable [it] may be used to destroy property and life. The art is already so far developed that the great destructive effects can be produced at any point on the globe, defined beforehand with great accuracy (emphasis added).

He seems to confess to such a test having taken place before 1915, and, though the evidence is circumstantial, Tesla had the motive and the means to cause the Tunguska event. His transmitter could generate energy levels and frequencies capable of releasing the destructive force of 10 megatons, or more, of TNT. And the overlooked genius was desperate.

Tesla was just enough of a mad scientist to make what would otherwise sound kooky, at least somewhat plausible.

Re:Google Maps

[isny]

Personally, this one looks like an impact crater. http://maps.google.com/maps?t=k&ie=UTF8&ll=60.9023 96,101.929779&spn=0.044828,0.10746&z=13&om=1 [google.com]