[meteorite-list] Tunguska Questions

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri, 15 May 2009 13:34:02 -0500
Message-ID: <4528F8196D1E4FF2A85498DE1147FEEC_at_ATARIENGINE2>

Eric, List

In order to get the original data, the facts on the
ground and to get as close in time to the event,
but more scientifically sophisticated and prior
to Tunguska being adopted by whackoes and
ufo-theorists, I suggest this exhaustive
summary of the result of the 1961 Soviet
large-scale expedition to Tunguska, from
Meteoritica, XXIII (1963):
http://abob.libs.uga.edu/bobk/tungmet.html


The Lake Cheko paper by Gasperini that suggests
it is a secondary crater:
http://www-th.bo.infn.it/tunguska/GasperiniSvalbard.pdf

Gasperini works with the U. of Bologna group.
The only academic on-going research program
into Tunguska is carried on by the University
of Bologna (Italy). There is a wealth of material
at their website:
http://www-th.bo.infn.it/tunguska/
and I suggest you follow those many links on
their website to dozens and dozens of informative
websites, Gasperini's work at Lake Cheko, many
photos from past expeditions, summaries of past
research -- all you ever wanted to know about
Tunguska but were (not) afraid to ask...

There are links to a variety of material on this
website maintained by the Novosibirsk Computer
Center:
http://omzg.sscc.ru/TUNGUSKA/

particularly the excellent works of Academician Vasilyev
who does an admirable job of giving the pro's and con's
of every theory about Tunguska:
http://omzg.sscc.ru/TUNGUSKA/en/articlese/tmpt.html
and
http://omzg.sscc.ru/TUNGUSKA/en/articlese/vasiljeve.html

They also host this article by Roy Gallant:
http://omzg.sscc.ru/TUNGUSKA/en/articlese/gallantst.html

The natives, the Evenki, believed (half a century ago)
that the events of that day were the result of a duel
between two rival tribal sorcerers and, hey! it's no
crazier than some of the other theories about Tunguska.

Calculating the actual force of the "impact" is guesstimation.
There's the evidence of the "toothpick forest," flattened by
the explosion, but the answer is sensitively dependent on
just how high the airburst was. The suggested height ranges
from 2400 meters to 9600 meters, producing a calculated
explosion of a minimum of 15 Megatons to a maximum of
40 megatons

Another method is from the trace of the barometric pressure
wave (which passed at least 2-1/2 times around the planet),
recorded by the brand-new invention, the chart-recording
barometer. The initial pulse is consistent with a force of
mid-20-ish megatons, right in the middle of the 15-40
megaton range.

I tried reconstructing the force from the witness accounts
of the light of the flash, in visible light flux at the distant
railway station and in the infrared flux experienced on
the porch at Varavana. A big thermal event has a "black-body"
distribution of energies across the spectrum that varies
with the temperature of the event. I got a 28 megaton event
but with error bars that run from 22 megatons to 34 megatons.

So, all these different methods seem to point to a similar
spread of possible force of the explosion. Yeomans, as a
government scientist, is of course giving the absolutely
minimum figure of 15 megatons so he can't be criticized
for exaggeration or for scaring people. Tunguska is a
magnet for kook theories and it spooks "regular" scientists
to get too close.

    In my calculation, thanks to the Stefan-Bolzmann Law
I could calculate a temperature for the event as well, and
it was a very high temperature, requiring an energetic
plasma event to achieve, which brings us to the Boslough
Theory of the "Plasma Dragon" of Tunguska:
http://www.sandia.gov/news/resources/releases/2007/asteroid.html

I have a theory too but it's too whacky for the margins of
this email. For more information search the List Archives;
they are rife for ten years with Tunguska postings and
-- for Godsake -- Google! (1,320,000 hits)



Sterling K. Webb
-----------------------------------------------------------------------------------------
----- Original Message -----
From: "Meteorites USA" <eric at meteoritesusa.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Friday, May 15, 2009 11:16 AM
Subject: [meteorite-list] Tunguska Questions


> Hi all,
>
> In regard to Tunguska and bioturbation.
>
> Paul H's post on bioturbation brings up an interesting question. The
> first expedition led by Leonid Kulik to Tunguska in 1927 to study the
> devastation and search for meteorites happened 19 years AFTER the
> event in 1908, (He had an earlier expedition in 1921 but wasn't
> successful in reaching the epicenter until 1927).
>
> 19 years is a LONG time for meteorites in the forested and swampy
> environment full of little critters, insects, and plants that could
> bury any stones. How deep can meteorites be buried in 19 years of
> snow, rain storms, mudslides, spring melt, critters, ants, termites,
> and other animals?
>
> Could bioturbation be one cause for the failed attempts to recover
> meteorites at Tunguska?
>
> You also have to take into account Leonid Kulik's mindset at the time.
> He was thinking that meteorites would be directly beneath the blast at
> the epicenter. Which made sense. Would he be looking for meteorites
> 10-40 miles away from the epicenter? He attributed the circular swampy
> bogs to craters formed by the meteorite impacts, which unfortunately
> turned out to be incorrect. Did he search for meteorites only under
> the epicenter? How far from the epicenter did his search area expand?
>
> Were there other expeditions to Tunguska to search in the 10-40 mile
> ring from the epicenter?
>
> Most scientists believe that the sheer force and energy of the blast
> at Tunguska event vaporized every trace of the meteoroid explaining
> that this is why there are no fragments to be recovered. This
> obviously makes sense, but would EVERYTHING be vaporized?
>
> Take a look at the "accepted" theory of Chixulub and the extinction of
> the dinosaurs. This widely accepted theory is now being challenged.
> Perhaps we should look at Tunguska again, in a new light.
>
> I am just wondering something out loud here about the Tunguska event.
> Yesterday I sent a load of links and questions and surprisingly got no
> response. Come on, this is the largest meteorite related blast in
> recent recorded history. So I'll will ask again.
>
> Is it possible that there are in fact meteorites that survived the
> Tunguska event by being blasted away much further from the epicenter
> than previously thought?
>
> Below is a copy of my post about some questions I had on Tunguska in
> yesterday's post.
>
> -----------------------ORIGINAL POST---------------------
>
> Hi Listees,
>
> Recently there's been more interest in the Tunguska event. More
> scientists are trying to explain it, and some are even looking at a
> lake
> near the blasts epicenter believing that this is the missing crater.
> http://news.bbc.co.uk/2/hi/science/nature/6239334.stm
>
> Photo of Lake Cheko:
> http://a52.g.akamaitech.net/f/52/827/1d/www.space.com/images/070626_lake_cheko_02.jpg
>
> A witness in Vanovara (36 Miles SE of the epicenter) said in O.
> Richard
> Norton's "Rocks From Space"
>
> "The crash was followed by noise like stones falling from the sky, or
> guns firing."
>
> and
>
> "when I lay on the ground I covered my head because I was afraid that
> stones might hit it."
>
> We all know too well that witness reports aren't ideal information but
> useful anyway. But, how would this person know to say that there was a
> "noise like stones falling" unless that were the case? Or did the
> witnesses report become tainted after countless interviews? How many
> times was this witness interviewed?
>
> I know people have searched for meteorites under and around the
> epicenter area. But what if this was a stony meteoroid, and the
> explosion blasted meteorite pieces 30-50 miles away. The devastation
> this explosion caused is evidence that it was one hell of a blast and
> was on par with a nuclear explosion.
>
> YouTube Video: http://www.youtube.com/watch?v=EiXpp-i442s
>
> Donald Yoemans (JPL) states in the History Channel video that this
> blast
> was 15 megatons of equivalent energy "roughly 1000 times that of the
> Hiroshima blast."
>
> VERY COOL ARTIST RENDERING: http://svidea.us/misha/image/tunguska2.jpg
>
> Photos of Devastation:
> http://astro.wsu.edu/worthey/astro/html/im-meteor/tunguska-photo.jpg
> http://upload.wikimedia.org/wikipedia/commons/a/ad/Tunguska.png
> http://www.wilsonsalmanac.com/images1/tunguska3.jpg
> http://www.world-mysteries.com/sci_tu3.gif
> Artist Rendering:
> http://aura.gaia.com/photos/34/338910/large/tunguska-1.jpg
> Area Map: http://www.world-mysteries.com/sci_tunguska1.gif
> Blast Damage Area: http://www.world-mysteries.com/sci_tu2.gif
>
> When you factor in all this information, how come people aren't
> looking
> 30-40 miles away for debris from this blast. If it was as powerful as
> they say (as evidenced by the downed trees and other devastation)
> wouldn't it make perfect sense that area around the blast would be
> completely void of meteorites as is the case?
>
> Having said that, wouldn't it be prudent to look further away from the
> blasts epicenter for fragments? How far will a blast such as that
> throw
> debris? If a Navy destroyer can launch a huge shell a hundred miles
> using a few pounds of gunpowder, how far can a meteoroid blast such as
> this launch stone fragments?
>
> Bomb squad techs and investigators will be the first to tell you that
> there's always something left over from a blast no matter how
> powerful.
> Pieces get thrown sometimes miles from the epicenter of powerful
> blast.
> In the case of Tunguska this blast was nuclear powerful! Yes a lot of
> the mass would have been melted and disintegrated but, how likely is
> it
> really that the blast would make ALL trace of the meteoroid disappear?
>
> Could there be meteorite pieces within a 30-50 mile ring around the
> epicenter?
>
> --
> Regards,
> Eric Wichman
> Meteorites USA
> http://www.meteoritesusa.com
> 904-236-5394
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Received on Fri 15 May 2009 02:34:02 PM PDT