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More Theories on Tunguska
<em>Science</em> ^ | Sept. 13, 2002 | Constance Holden

Posted on 10/28/2002 4:59:07 PM PST by aruanan

On 30 June 1908, in the remote Tunguska forest of Siberia, a vast explosion charred and flattened trees across an area nearly as large as Rhode Island. Scientists have long been mystified as to the cause, although prevailing wisdom has it that it was an extraterrestrial chunk of ice or rock (Science, 20 August 1999, p. 1205).


Figure 1
Tunguska epicenter today.

CREDIT: VITALII ROMEIKO


But two scientists last week rejected the "E.T. hypothesis" at a conference on environmental catastrophes in London. Andrei Ol'khovatov, formerly of the Soviet Radio Instrument Industry Research Institute, noted that no one has ever found definitive traces of extraterrestrial material. There's no impact crater, and some trees near the epicenter were left untouched.

Wolfgang Kundt, an astrophysicist at Bonn University, Germany, proposed an alternative scenario: a massive gas explosion. A large natural gas deposit lies below the site, a well-known fact unconnected to the event until now, he said. Kundt has modeled a Tunguska "outgassing" and says it would fit with eyewitness accounts.

"The geophysical hypothesis could be the answer," says Jesús Martínez-Frías of the Institute of Astrobiology in Madrid, Spain. But Ol'khovatov believes the explosion was caused by a "strong coupling between subterranean and meteorological phenomena" that science is not yet ready to understand.


TOPICS: News/Current Events; Russia
KEYWORDS: andreiolkhovatov; asteroid; catastrophism; cometimpact; jesusmartnezfras; naturalgas; russia; siberia; tunguska; wolfgangkundt
See The Origin of Methane (and Oil) in the Crust of the Earth by Thomas Gold.
1 posted on 10/28/2002 4:59:08 PM PST by aruanan
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To: blam
This looked like something you'd like.
2 posted on 10/28/2002 4:59:46 PM PST by aruanan
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To: aruanan
That would have been one hell of an earth fart!
3 posted on 10/28/2002 5:02:25 PM PST by commish
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To: aruanan; COB1; Dog Gone; CedarDave
bump
4 posted on 10/28/2002 5:02:53 PM PST by razorback-bert
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To: aruanan
It was a fart of the God(s), if you believe in that sort of thaing, otherwise, the universe simply let loose a "cheeser" that did not hurt anyone...
5 posted on 10/28/2002 5:04:33 PM PST by Vidalia
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To: aruanan
I'm glad somebody's talking sense about the Tunguska thing. Too bad Art Bell is retiring. I guess we can take off our tin-foil hats now.
6 posted on 10/28/2002 5:04:52 PM PST by MrJingles
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To: MrJingles
And how are the sighting of the object streaking through the sky explained? Was that gas bubble having a premonition?
7 posted on 10/28/2002 5:08:47 PM PST by per loin
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To: razorback-bert
I suppose that's possible, although this could be pretty easily ruled in or out by any competent geologist. It would require a shallow high pressure reservoir (unlikely right there) which is suddenly fractured (presumably by earthquake) with an enormous release to the surface of a couple hundred billion cubic feet of methane.

Presumably there is a campfire or other ignition source in the immediate vicinity.

The odds of this being the culprit behind Tunguska are very remote.

8 posted on 10/28/2002 5:13:12 PM PST by Dog Gone
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To: Dog Gone; razorback-bert
"The odds of this being the culprit behind Tunguska are very remote."

I agree, dog.
If we were talking about methane collecting in a valley from a shallow gas bearing sand, then suddenly exploding due to static electricity, I could buy that.
But I can't buy gas collecting in an area the size of Rhode Island!

The second possibilty is equally remote:
A deep high pressure sand is somehow suddenly relieved of it's overburden pressure and blows out.
The blowing out of the amount of gas necessary for that kind of explosion in that short of a time period is an unrealistic scenario.

9 posted on 10/28/2002 5:44:28 PM PST by COB1
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To: MrJingles
I guess we can take off our tin-foil hats now.

Keep that hat handy. Art's replacement is a lot like Art.

10 posted on 10/28/2002 5:49:40 PM PST by RightWhale
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To: aruanan
I read somewhere once [sorry I can't quote it] that Nicola Telsa was doing some massive experiment at that exact time involving the earth's magnetic field and the transmission of electricity.
11 posted on 10/28/2002 5:58:29 PM PST by karlamayne
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To: COB1; Dog Gone
Hey, with further thought this works for me, I just remembered that Project Blue Book use to blame UFOs on swamp gas.


I am dealing with a "know it all geologist" right now ,will ask him.
12 posted on 10/28/2002 6:29:54 PM PST by razorback-bert
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To: Vidalia
the universe simply let loose a "cheeser"

Was it Drippy like a Chedder aged on a dashboard of a Pinto in Palm Springs.......?
13 posted on 10/28/2002 6:32:50 PM PST by cmsgop
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To: aruanan
So you are saying the Earth "BLEW THE BOWL" !!!!!!!!!!!
14 posted on 10/28/2002 6:34:44 PM PST by cmsgop
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To: cmsgop
Thanks for keeping this pic alive.

It is unReel.

Good job on the slo mo of the slob-child of Bill and Hillary.

Gee, where did ya get it:::?
15 posted on 10/28/2002 6:57:26 PM PST by Vidalia
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To: RightWhale

16 posted on 10/28/2002 7:17:30 PM PST by ALS
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To: Dog Gone
It would require a shallow high pressure reservoir (unlikely right there) which is suddenly fractured (presumably by earthquake) with an enormous release to the surface of a couple hundred billion cubic feet of methane.

And yet gaseous explosions are quite often associated with earthquakes. Also, some earthquakes may themselves be due to structural failure of rock and the release of vast quantities of methane, with or without subsequent ignition. Although it was believed previously that the fires of the San Francisco earthquake were due to broken gas mains, there is evidence that they were not due entirely to this.

In addition, methane hydrates are found not only underwater but in the tundra. A sufficiently large atmospheric blast due, say, to a chunk of comet, could provide enough pressure to destabilize large amounts of hydrate resulting in a near instantaneous release and subsequent ignition of the gas.
17 posted on 10/28/2002 7:19:05 PM PST by aruanan
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To: aruanan
The thing blew up in the air, like an air-burst Hiroshima bomb only bigger. Modeling shows that a stony meteorite would do that, or any icy body like a comet. An iron meteorite of comparable size would augur all the way in, so that's one thing that can be eliminated.
18 posted on 10/28/2002 7:23:27 PM PST by VadeRetro
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To: VadeRetro
... would augur all the way in ...

It augurs poorly that I forgot the difference between auger and augur.

19 posted on 10/28/2002 7:28:41 PM PST by VadeRetro
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To: cmsgop
This is *ALL* propaganda put out by the anti-smoking Nazis, IMO. Can't smoke anywhere.
20 posted on 10/28/2002 7:48:26 PM PST by Calvin Locke
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To: aruanan
As mentioned above, there were numerous sightings over a wide area of the fireball passing overhead before the explosion.

Several of them even thought the object changed directions, leading to the idea it was a crashing spaceship.
21 posted on 10/28/2002 8:42:59 PM PST by chaosagent
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To: aruanan
Explain to me the cause of the "Butterfly" pattern of fallen trees with the trees at the center burned but standing up.
22 posted on 10/28/2002 9:45:14 PM PST by Mike Darancette
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To: blam
PING(((((((
23 posted on 10/28/2002 9:46:05 PM PST by Mike Darancette
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To: chaosagent
Several of them even thought the object changed directions, leading to the idea it was a crashing spaceship.

Fire has been observed to streak through the skies in the vicinity of outgassings (such as off the coast of North America). An apparent change of direction would be more likely observed under these conditions than for a fireball of extraterrestrial origin.
24 posted on 10/29/2002 12:34:05 AM PST by aruanan
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To: aruanan
I don't like this idea.

Do you have anything on the recent meteorite impact?

25 posted on 10/29/2002 5:37:49 AM PST by blam
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I think it was a bunch of "rods." which several people on FR are convinced are missiles being fired at airliners.

Actually I gotta go for meteor of some type. I saw an interview with a couple of eyewitnesses who saw the big streak in the sky.

26 posted on 10/29/2002 5:42:44 AM PST by KneelBeforeZod
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To: KneelBeforeZod
I think it was a bunch of "rods."

Well, if you decide to change your name, "KneelBeforeRod" is still available.

Not that you'd probably want it - the porn angle is pretty hard to avoid with a name like that... :^)

27 posted on 10/29/2002 6:04:41 AM PST by general_re
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To: aruanan; RightWhale
Source: University Of Illinois At Urbana-Champaign
Date: 10/29/2002

Scientists Studying Two Big Craters On Earth Find Two Causes

CHAMPAIGN, Ill. -- Two of the three largest impact craters on Earth have nearly the same size and structure, researchers say, but one was caused by a comet while the other was caused by an asteroid. These surprising results could have implications for where scientists might look for evidence of primitive life on Mars.

Susan Kieffer of the University of Illinois at Urbana-Champaign, Kevin Pope of Geo Eco Arc Research and Doreen Ames of Natural Resources Canada analyzed the structure and stratigraphy of the 65 million-year-old Chicxulub crater in Mexico and the 1.8 billion-year-old Sudbury crater in Canada.

Chicxulub is well preserved, but buried, and can be studied only by geophysical means, remote sensing and at a few distant sites on land where some ejecta is preserved. In contrast, Sudbury has experienced up to 4-6 kilometers of erosion, and is well exposed and highly studied by mining exploration companies because of its rich mineral resources.

By working back and forth with data from the two craters, the researchers were able to re-create the structures and then estimate the amount of melt in each structure. The amount of melt is critical for determining if long-lived hot-water circulation systems that might host life forms could have been formed after the impacts.

In their field studies, the researchers found that both craters were about 200 kilometers in diameter. In addition, they identified five ring-shaped structures with similar character and dimensions. A sixth ring -- the peak ring in the central basin -- was present at Chicxulub, but had been eroded away at Sudbury.

"While the size and structure of the two craters were similar, they differed greatly in the amount of impact melt that was produced," said Kieffer, who presented the team's findings at the annual meeting of the Geological Society of America, held Oct. 27-30 in Denver.

"Through field studies, we determined that Chicxulub has about 18,000 cubic kilometers of impact melt, approximately four times the volume of water in Lake Michigan," Pope said. Sudbury has about 31,000 cubic kilometers of impact melt, approximately six times the volume of lakes Huron and Ontario combined, and nearly 70 percent more than the melt at Chicxulub. These differences in volume have significant implications about the amount of heat available to drive hot-water circulation systems.

The researchers then used an analytical cratering model to examine possible causes for the huge difference in melt. According to the simulation results, the difference in melt volume could be readily explained if Chicxulub -- the impact crater that doomed the dinosaurs -- was formed by an asteroid and Sudbury was formed by a comet.

"Our calculation of 18,000 cubic kilometers of impact melt at Chicxulub agreed well with model estimates for an asteroid striking at a 45 degree angle," said Kieffer, the Walgreen Professor of Geology at Illinois. "None of the comet impact examples came close to agreeing."

"In contrast, the Sudbury impact melt volume of 31,000 cubic kilometers fell between model estimates for a comet striking at an angle of 30-45 degrees", Kieffer said. "Similarly, none of the asteroid impact examples came close to agreeing with the Sudbury melt volume."

Another clue to the cratersÕ origins lies in the impact melts themselves. The majority of the excess melt at Sudbury is in the form of a melt-rich breccia Ð called suevite Ð inside the crater. This material tends to form in impacts where the crustal target rock contains a lot of water. Sudbury has much more suevite in the preserved crater than Chicxulub.

"The mystery was that there probably wasn't a lot of water in the original rocks at Sudbury to account for the excess suevite," Kieffer said. "But in a comet impact of this size, somewhere around 1,400-2,000 cubic kilometers of water from the comet gets mixed into the impact melt, and that could play a major role in disrupting the melt and creating the excess suevite."

There is other independent evidence for an asteroid impact at Chicxulub, the team said, including the purported find of an asteroid fragment in an oceanic drill core, the amount of iridium spread around the world at the time of impact, and a telltale chromium 53 isotopic signature.

By studying the origin and structure of large impact craters on Earth, scientists might narrow the search for life on Mars. At Sudbury, for example, "there is evidence of a huge hydrothermal system that was driven by the heat of the impact melt," Ames said. "As a result, there was widespread hot spring activity on the crater floor possibly capable of supporting life."

The researchers are interested in "extrapolating these conclusions about comet and asteroid impacts to Martian conditions and asking where we might go to look for similar hydrothermal systems that could have hosted primitive life forms on Mars," Kieffer said. "Our next step is to model these hot-water circulation systems that were set up by the impact melts with fluid flow controlled by structures (fractures) inside the crater, and then extrapolate the results to Martian conditions."

The National Aeronautics and Space Administration and the Natural History Museum of Los Angeles County funded this work.

28 posted on 10/29/2002 6:35:34 AM PST by blam
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To: blam
Cool post. I've been to Sudbury.
29 posted on 10/29/2002 8:08:26 AM PST by aruanan
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To: blam
Somewhat odd results since the Canadian nickel is supposedly remains of an ancient asteroid impact.
30 posted on 10/29/2002 9:01:25 AM PST by RightWhale
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Note: this topic is from 10/28/2002. Thanks aruanan.



31 posted on 07/15/2012 7:44:48 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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