[meteorite-list] Ground penetrating radar at Carancas?

From: Michael Farmer <meteoriteguy_at_meteoritecentral.com>
Date: Sat, 6 Oct 2007 09:10:17 -0700 (PDT)
Message-ID: <64804.93221.qm_at_web33115.mail.mud.yahoo.com>

so you can write this idea off, the water table at
Carancas is halfway up the crater, and the meteorite
should be several meters below it.
The rains will begin in a few weeks, and the water
table will spill over the top of the crater,
unstoppable and the tourist attraction will cease to
exist. I tried to explain that to the Peruvian
officials with nothing more than almost going to
prison as a result. The meteorite community and
scientists will watch this debacle in slwo motion, the
loss of one of the most important meteorite falls in
decades.
Michael Farmer
--- Arizona Keith <arizonakeith at cox.net> wrote:

> Hello Piper and List
>
> I used GPR before, and yes it has limitations.
>
> 1. It can't see past the water table, blocks the
> signal, or reflex
> signal completely, and you see nothing past it.
> 2 Wet and dry clay soils weaken and/or block the
> signal completely, you
> send out a signal and it doesn't come back.
> 3. Depending on the frequency, Units can see
> small objects close to the
> surface, deeper you go, the large frequency you
> need, and only large items
> can be seen at great depths, the unit I used range
> between 1 to 45 foot
> depths, It's seen 3' dia. manhole covers buried 25'
> deep, but not 8" valve
> covers at that depth.
> 4. Metal objects vibrate, they stand out great,
> stony meteorites don't
> stand out well, I tested it on some, But you can see
> the changes in the
> layer of bedding, the bedrock and the disturbance of
> the impact on them,
>
> 5. Most GPR units only work looking straight
> down, so the area needs to
> be flat and level for best results.
>
> Hope this helps, good night all.
>
> Thanks for your time
> Keith
> Chandler AZ
>
>
> ----- Original Message -----
> From: "Piper R.W. Hollier" <piper at xs4all.nl>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Friday, October 05, 2007 11:30 PM
> Subject: [meteorite-list] Ground penetrating radar
> at Carancas?
>
>
> > Hello again list,
> >
> > Ground penetrating radar (GPR) is commonly used
> for non-destructive
> > investigation of archaeological sites. GPR "can
> detect objects, changes in
> > material, and voids and cracks." (Wikipedia) Has
> anyone thought of mapping
> > the crater with GPR before sending in a backhoe to
> rip it open? This could
> > be one way to have some idea whether there are
> meteorite masses under the
> > ground, how large, and where, before starting to
> dig. It could also yield
> > valuable information about the morphology of the
> crater, with potentially
> > more precision and detail than digging would
> allow.
> >
> > Can someone on the list comment on the state of
> the art of GPR? How deep
> > can it penetrate nowadays? (Wikipedia says 15
> meters, best case.) Would a
> > high water table be a problem? (Wikipedia says
> that range would be greatly
> > reduced in "moist and/or clay laden soils.") Are
> there new designs or
> > techniques that could get around such limitations?
> >
> > In any case, there would be some thorny practical
> problems to be dealt
> > with. Ordinarily the antennas need to be nearly in
> direct contact with the
> > ground, which would seemingly make it very
> difficult, if not impossible,
> > to do a scan of an area where the ground surface
> is anything but flat. Or
> > has someone come up with a "workaround" for this
> issue in a similar
> > situation?
> >
> > Best wishes to all,
> >
> > Piper
> >
> > ______________________________________________
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> > Meteorite-list at meteoritecentral.com
> >
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> >
>
>
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Received on Sat 06 Oct 2007 12:10:17 PM PDT