Bonsoir Arnauld -
When I stumbled into Clube and Napier's work and others in 1997 was when I
realized that the NASA rates from asteroid population were too low. Its
cometary and comet fragment impacts, and the small fragments are damned hard to
find.
I think Shoemaker's final paper out of Canada had better rates. The ones that I
came up with were just from historical/myth-historical materials, but with
archaeological confirmation - i.e. for the YD impacts there's quarry usage data.
E.P. Grondine
Man and Impact in the Americas
--- On Sun, 11/15/09, The Tricottet Collection wrote:
> From: The Tricottet Collection
> Subject: RE: [meteorite-list] Tunguska rates
> To: "E.P. Grondine" , "MeteoriteList"
>
> Date: Sunday, November 15, 2009, 3:01 AM
>
> Hi E.P. et al.,
>
> actually, what the journalist of BI wrote is inaccurate.
> You can read in our report that we used 1 per 1000 years as
> our preferred value, following the most up-to-date
> frequency-size distribution [Brown et al, 2002], but we also
> tested 1 per 200 years [Shoemaker, 1983] and noted that the
> rate could be far higher if hypotheses from geomythology and
> related were to be verified.
>
> Best,
>
> ArnaudM
>
>
>
> > Date: Sat, 14 Nov 2009 18:20:11 -0800
> > From: epgrond...@yahoo.com
> > To: meteorite-list@meteoritecentral.com
> > Subject: [meteorite-list] Tunguska rates
> >
> > Hi Arnauld, all,
> >
> > The problem is that Tunguska type blasts have been
> occuring recently (for the last 5,000 years) at a rate of 1
> per 100 years, not 1 per 1,000. Whether this represents a
> short term phenonmenon or the long term rate is not
> currently known.
> >
> > I used to put together catalogues of "known and
> suspected impacts", you may want to google that, and if you
> have not bought a copy of "Man and Impact in the Americas"
> yet, well, it is the best available recent impact rate data
> for the Americas.
> >
> > E.P. Grondine
> > Man and Impact in the Americas
> >
> >
> >
> > __
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>
>
>
>
> _
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> star.
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