[meteorite-list] tunguska explosion data

From: Keith <littlejo_at_meteoritecentral.com>
Date: Thu Apr 22 09:52:18 2004
Message-ID: <Pine.SOL.4.33.0208192043180.11376-100000_at_katie.vnet.net>

On Thu, 15 Aug 2002 10:23:49 -0700 (PDT)
alvie roach jiujitsu11_at_yahoo.com wrote:
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>I am trying to prove a dry lake is in fact a meteorite
>crater. A meteorite was found in the area, the bed rock
>is shattered for miles in every direction and the
>shape of the dry lake seemes to have a ballistic
>signature.I am hopeful someone can help me access the
>experiment data that determined the hight and angle of
>the explosive event at tunguska.the discovery channel
>had a program about tunguska.In this show was a
>section on how the scientists determined the hight and
>angle. They flew a series of charges over a forest of
>pins on a test board and recorded the shapes left by
>the explosions.They continued this until they came up
>with the butterfly pattern of tunguska.I am confidante
>the shape of my dry lake will be in this data.I hope
>you can help me.
>Contact me at jiujitsu11_at_yahoo.com.
>Thank you,Alvie Roach
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What you are looking for is a circular structure. Even
then it is a long shot as Shoemaker once remarked that
for every meteorite impact crater their are 10,000 circular
features that look lie one. Because of this, you really
should go look at " What general criteria classify a
depression as an impact crater?" that is part of "The
Wetumpka Impact Structure" at:
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http://www.auburn.edu/academic/science_math/geology/docs/wetumpka/gen.htm
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The four criteria listed at that web page are:
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1. morphology
2. evidence of shock metamorphism
3. geochemical evidence
4. presence of geophysical anomalies
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All of these criteria are discussed in great detail in:
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Koeberl, C. and R. R. Anderson (1996) Manson and company:
Impact structures in the United States. In: The Manson
Impact Structure, Iowa: Anatomy of an Impact Crater,
C. Koeberl and R. R. Anderson, eds., pp. 1-29, Geological
Society of America, Special Paper no. 302.
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For crater morphology and evidence of shock metamorphism,
go read:
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Melosh, H. J. (1989) Impact Cratering: A geologic
process: Oxford University, New York, New York. 245 p.
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For a detailed discussion of evidence of shock metamorphism
and geochemical evidence a person definitely needs to find,
go read
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Montanari, A., and C. Koeberl (2000) Impact Stratigraphy:
The Italian Record. Lecture Notes in Earth Sciences. Vol. 93,
Springer Verlag, Heidelberg, 364 pp.
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(This book also has fascinating sections on tektites and
Libyan Desert Glass, which are a must read for anybody
interested in any of them.)
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For an over view of geophysical signatures of impact
craters, go read:
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Grieve, R. A. F., and M. Pilkington (1995) The signature
of terrestrial impacts: Journal of Australian Geology
and Geophysics. vol. 16, pp. 399-420.
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Plescia, J. B. (1993) Gravity investigations of terrestrial
impact craters: EOS (Transactions, American Geophysical
Union). vol.74, p.387.
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Pilkington, M. and R. A. F. Grieve (1992) The Geophysical
Signature of Terrestrial Impact Craters." Reviews of
Geophysics. vol. 30, pp. 161-181.
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Have Fun
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Keith
New Orleans, LA
Received on Mon 19 Aug 2002 08:44:43 PM PDT