[meteorite-list] Large (future) impact

From: joseph_town_at_att.net <joseph_town_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:29 2004
Message-ID: <022820040144.28888.4d45_at_att.net>

Arbitrarily, obvious math, estimated, little difference, safe to assume, I suspect, I think, etc. Thats enough please.

Bill Kieskowski



> While I agree that my number of '1000 years' was picked arbitrarily, to be
> realistic, if we can not prepair hardened food production facilities within
> the warning time avalible, it would matter little if the 'nuclear winter'
> lasted for 1000 years or only a few years, as both numbers are well over the
> elngth of time a human can go without food, even your average overweight
> american! :)
>
> Also, with regards to an impact that would cause long term effects in
> comparison to prompt killoffs, keep in mind that the blast radius of an
> explosion scales at the cube of the energy released, whereas the amount of
> dust that gets kicked up into the air scales pretty linearly. So to point
> out the obvious math, when you compare 2 impacts, one that causes a prompt
> damage of radius 'x' to one that causes prompt damage of radius 2x, the
> latter will eject 8 times as much material into the air. 3x you are at 27
> times as much material, and so on. (this rule of thumb applies to nuclear
> weapons and other 'conventional' explosions, as impact events liberate
> energy during their entire trip through the atmosphere, the numbers may be a
> little diffrent, but I'd say they are close enough for the purpose at hand).
> To put that in perspective, an impact event that liberates 1000 times as
> much energy (and hence dust into the atmosphere) as krakatoa would only have
> a damage radius of about 250 miles (defined as the point where buildings,
> trees, ect are knocked over) and a thermal burn radius of about 1000 miles,
> but I suspect that number is a bit off, as the curvature of the earth would
> come into play by then. Obviously there are many places where such an impact
> could occur without killing any signifigant number of people (in the global
> sense)
>
>
> I think that it's safe to assume there are a large number of areas on the
> planet where an impact could occur that would cause orders of magnitude more
> climate altering dust to go into the atmosphere, than say krakatoa, without
> killing off a large portion of the life on this planet.
>
>
> >On the subject of the aftermath of a large impact -- specifically the
> >duration of
> >"nuclear winter", Stan wrote:
> >
> > > "In the event of a large impact, we would need to build an enclosure
> >that
> > > protects food crops from the environment, and provides an alternate
> >source
> > > of energy to the crops. Rice isn't going to grow if the sun is blacked
> >out
> >for
> > > 1000 years because of a comet induced nuclear winter."
> >
> >An impact that doesn't kill everyone and everything within hours should not
> >have effects lasting anywhere near that long. Months to a few years, I
> >would
> >guess, depending on the size and velocity of the impactor. It's a very
> >difficult
> >thing to estimate since the only contemporary, large energy releasing
> >events
> >we have to compare to are many orders of magnitude smaller in energy.
> >Krakatoa's four explosions on August 27, 1883, for instance, are estimated
> >to have released the energy equivalent of around 200 megatons of TNT. They
> >gave us red sunsets for more than a year and lowered global temperatures as
> >much as 1.2 C.
>
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Received on Fri 27 Feb 2004 08:44:21 PM PST