[meteorite-list] Million's of Dollars of Tunguska Meteorites may be located, just like Chelyabinsk's Meteorites: OUTSIDE of, NOT INSIDE, the Blast Zone.
From: MEM <mstreman53_at_meteoritecentral.com>
Date: Sun, 5 May 2013 22:57:04 -0700 (PDT)
IIRC a researcher( name not remembered) went to the Tunguska "strewn forest" and took the azimuth of several thousand knocked over trees and worked up a trajectory, altitude, and yield for the Tunguska object with matched computer modeling.? (Someone should find the research paper and correct my memory)
The heat blast scorched trees several miles from the disruption--like the wooden fence posts and window sills of buildings near the Trinity shot.? To release that much infrared energy the object had to be traveling at cometary velocities (vs asteroid velocities--another major clue pointing to a comet).? It also supports the idea that nothing other than silicate vapor survived what was equivalent to a high KT yield-- greater(?) than any "fussion bomb" ever exploded.
So I respectfully disagree that there are any Tunguskan meteorites and never were.
> From: Rob Matson <mojave_meteorites at cox.net>
>To: 'Steve Arnold' <meteorhntr at aol.com>; meteorite-list at meteoritecentral.com
>Sent: Sunday, May 5, 2013 11:25 PM
>Subject: Re: [meteorite-list] Million's of Dollars of Tunguska Meteorites may be located, just like Chelyabinsk's Meteorites: OUTSIDE of, NOT INSIDE, the Blast Zone.
>> Robert Beauford and I were talking about Chelyabinsk shortly after the
>> fall and he asked how many Chelyabinsk meteorites were being found
>> in the city of Chelyabinsk, where all the windows had been blasted out?
>> I told him that, as I understood it, the strewnfield was farther "down
>> stream" because inertia carried the rocks further beyond the blast,
>> like what almost always happens with fireballs.
>The real reason nothing will be found in the city of Chelyabinsk itself
>is that the meteoroid did not pass over the city. The closest point to
>Chelyabinsk under the fireball path was 35 km to the south-southeast.
>Even Korkino was north of the fireball's path. The main burst was
>about 26 km above the city of Pervomayskiy, but prevailing winds
>were to the southeast, so the closest meteorites would have fallen
>south of that city.
>> We later talked about how the Tunguska event of June 30, 1908,
>> was bigger than Chelyabinsk it seemed, but probably not as big as
>> the 101 crater forming event of Sikhote Alin, Russia of Feb. 12,
>> 1947. Certainly, Tunguska was not as big as what caused the
>> near-mile-wide Barringer Crater in Arizona. All of a sudden, it
>> hit Robert..."Maybe there really should be Tunguska meteorites,
>> but not where everyone has been looking for the last 105 years!"
>> ... So why would there be Tunguska meteorites amongst the
>> fallen trees at the Tunguska blast zone?
>I agree that if meteorites made it to the ground, you would not
>expect them to be concentrated at the epicenter of the terminal
>burst (presumably the center of the fallen tree zone). But they
>would almost certainly be within it. The Tunguska terminal burst
>was at rather low altitude (likely 10 km or lower), while the
>radius of the zone of devastation is something like 25 km. So
>unless Tunguska's entry angle was very shallow and/or upper
>atmospheric winds were extremely high, it would be difficult
>for meteorites to travel 25 km downrange of that terminal
>I do not believe the entry angle for Tunguska was particularly
>steep or shallow; I think I remember the consensus is that it was
>average, e.g. 30 degrees from horizontal. [Side note: 30 degrees
>*is* the exact average entry angle, not 45 degrees.] So even if
>the terminal burst was as high as 10 km, and there was no
>atmospheric drag, meteorites could only travel about 17 km
>downrange from the terminal burst.
>Where meteorites would end up relative to the epicenter of
>devastation depends on a combination of the original flight
>direction, and the prevailing winds at the time and location of
>the fall. There isn't consensus on that flight direction, though
>based on the evidence I've seen I would estimate that it was
>to the west-northwest. Unfortunately, the prevailing winds
>are unknown, but you could probably bound them by examining
>several years of historical data for mid-June to mid-July for
>that general region of Siberia at around 0h UT. In fact, I think
>that would be an excellent research project! I might even
>tackle it myself...
>> If we are right, WHERE should someone be looking to actually
>> find the potentially millions of dollars of meteorites that have
>> been waiting to be found all this time?
>Based on my arguments above, *inside* the tree devastation
>zone (which isn't very helpful, given that it covers some
>2000 square kilometers!) Flight direction favors the western
>half of that zone [hey, down to 1000 sq. km ;-) ] I would want
>to run some Monte Carlo cases with different assumptions
>for wind, terminal burst altitude and flight direction to better
>constrain the fall zone. Ultimately, the choice of wind speed
>and direction is going to drive the answer to your question.
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Received on Mon 06 May 2013 01:57:04 AM PDT