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Re: Hell Creek (long)



On Thu, May 30, 2002 at 05:06:03AM -0400, MariusRomanus@aol.com sent:
> Yup...... and I touched that a bit in another post. Sandia did a
> simulation of an oblique 30 degree angled impact from an asteroid some
> 1.2 km in diameter off the coast of New York. It was interesting in
> that there was mostly just super heated plasma and vapor involved in
> the resulting blast directed right at the city from an elliptical
> cavity in the ocean..... very little sea bottom was excavated. There
> was very, very little in the way of material being directed up into
> the atmosphere for global trajectories or a dust cloud. Sandia also
> did a simulation with a 1.2 km comet striking the ocean off the coast
> of New York. Once again there was very little sea bottom involved in
> the resulting blast..... It was mostly all super heated plasma and
> vapor.... But this time the impact was at a 45 degree angle which
> caused ALL of the blast force to be directed straight up and right out
> of the atmosphere from the round cavity of water that was sculpted out
> of the ocean...... The blast force was hundreds of magnitudes larger
> then that of the oblique asteroid impact..... a ridiculous 400
> gigatonnes or something like that.... Really amazing stuff...... And
> these results fit oh so nicely with my post to Rob about the dust
> cloud.

Except that you're citing an order of magnitude smaller impactor
diameter which is _three_ orders of magnitude less mass and which
renders the simulation pretty much useless as an indicator for the
Chixuculb impact's behavour.

Fireball geometry doesn't scale linearily with size, but there are very
some significant scale points, especially the 'fireball diameter larger
than the tropopause height' and the 'fireball diameter larger than the
atmosphere height' ones.

-- 
graydon@dsl.ca   |  Hige sceal þe heardra, heorte þe cenre,
                 |  mod sceal þe mare þe ure maegen lytlað.
                 |   -- Beorhtwold, "The Battle of Maldon"