On Wed Aug 02 2000 - 00:45:02 EDT and
in " Re: Meteor Program," Diane Roy
(Dianeroy@peoplepc.com) wrote:
>The point at which all the asteroids which made impact
>craters exploded is below ground level. This shields
>the immediate area from the bright flash which
>accompanies air and surface blasts that causes
>intense heat and instant burning. Most of the energy is
>released upward.
I would suggest that Diane Roy skim through:
Melosh, H. J. (1989) Impact cratering; a geologic process.
Oxford Monographs on Geology and Geophysics. no. 11,
Oxford University Press. Oxford, United Kingdom. 245 pp.
The proposal that "Most of the energy is released upward"
is simply not true. Energy is converted into blast impact
waves that be very destructive to anything and anybody
nearby. Energy is also converted in seismic waves that
would create massive earthquakes. The ionization of gases
at the instant of impact and the massive ejection of
molten material from the vaporization of the meteorite
and the target rock would produce a brilliant light
flash in ultraviolet, visible, and infrared. The infrared
wavelengths would cause a thermal radiation impulse whose
fire-ignition effects would be subject to the scaling-
law function (King 1976).
For example, the thermal pulse from a stoney-iron
meteorite with a diameter of only 175 meters (574 feet)
would ignite vegetation in a radius of 47 km. The seismic
response to even this small of asteroid would be
equivalent to either the San Francisco or Alaskan Good
Friday earthquake. Destructive blast waves would have
extended as far as 96 km from the impact. If this
meteorite hit shallow water, a tsunami wave 140 to 285
meters (459 to 935 feet) high would result. (Neathery
et al. 1997). This is what a small meteorite will do.
... text deleted ...
>All asteroid impacts creating impact craters are the
>same as un-contained underground blasts. These
>asteroids are so big that the air does not cause
>enough compression. It is only after entering the
>ground that critical mass is reached. The blast
>of an un-contained underground blast is even less
>destructive than a surface blast.
According to King (1976) and Melosh (1989) the blast
is not fully contained underground. A large impacting
meteorite will create immense lateral blasts and
earthquakes that will make life quite unpleasant
in the region of an impact.
>The bright flash is fully contained underground,
>so instant fires cannot happen.
Ionization of the atmosphere will occur as well the
ejection of massive amounts of molten material from
the crater will create thermal effects that will
cause instant fires. Anybody who doesn't believe me
can check the discussion on the topic in King (1976)
and Melosh (1989)
>The shock wave is directed almost entirely upward.
>A much diminished shock wave does follow along on
>the ground. Most of the energy of the blast is
>absorbed into moving the earth outward and upward.
This might be true, but with the enormous energy
released by an impact, even if only a fraction of
it goes into blast and a thermal pulse, the result
of each will be devastating.
>Is this all accounted for in your program?
There is no reason for Glenn to account for claims
that a simple reading of King (1976) and Melosh (1989)
will easily refuted as being incorrect. The existence
and magnitude of the effects that Diane Roy denies
out of hand can be verified by looking through the
articles in Geheris (1994).
References Cited:
Geheris, T., ed. (1994) Hazards Due to Comets and
Asteroids. University of Arizona Press, Tuscon. 989 pp.
King, D. A. (1976) Space Geology. Wiley and Sons,
New York. 349 pp.
Melosh, H. J. (1989) Impact cratering; a geologic process.
Oxford Monographs on Geology and Geophysics. no. 11,
Oxford University Press. Oxford, United Kingdom. 245 pp.
Neathery, T. L., D. T. King, and L. W. Wolf (1997) The
Wetumpka Impact Structure and Related Features. Guidebook
Prepared for the Annual Meeting of the South Eastern
Section, Geological Society of America. Alabama Geological
Society, Tuscaloosa, Alabama.
----- Original Message -----
From: glenn morton
To: ASA@calvin.edu
Sent: Tuesday, August 01, 2000 2:46 PM
Subject: Meteor Program
>Given all the nonsense about meteors causing the
>flood, I have decided to put out on my web page a
>program that I wrote from a Sky and Telescope
>article (Unfortunately I forget when it was
>published--somewhere back in '93).
... text deleted ...
Keith Littleton
littlejo@vnet.net
New Orleans, LA
"X-rays will prove to be a hoax."
--Lord Kelvin (1824-1907) in Robert Youngson,
"Scientific Blunders: A brief history of how
wrong scientists can sometimes be," Robinson,1998
"Heavier-than-air flying machines are impossible."
-- Lord Kelvin,1895. From (Morgan and Langford's
"Facts and Fallacies: a Book of Definitive
Mistakes and Misguided Predictions" - 1982)
"Radio has no future."
-- Lord Kelvin, 1897, on Marconi's experiments
From "Facts and Fallacies: a Book of Definitive
Mistakes and Misguided Predictions" - 1982)
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