Im No Physics Major,
But they seem to be already doing this
Closer to the surface,

You would want to do many different kinds of
processing looking into the noise (grass)
and simply look for correlations of data to
whatever.

In Sonar you reflect sound off a velocity
change and it comes back to the transmitter.

Possibly a fathometer like device which
reflects vibrations off the moho ?

Have no idea how such equipment could be built.
You need lots of energy into such a transmitter.
Like maybe a MOAB ?




-----Original Message----- 
From: Christopher Chapman
Sent: Thursday, March 10, 2011 4:23 PM
To: psnlist@..............
Subject: Re: Representative stationsOn 9 March 2011 18:38, Geoffrey  wrote: (and IRIS station list)



From: Dan Bolser dan.bolser@.........
Sent: Thu, 10 Mar 2011 9:13
Subject: Re: Representative stations (and IRIS station list)


Sounds like a good idea. By how much does the density of the rocks actually change?  So, just how do you propose to measure, with 
some precision, the speed of sound in some rock, say 100 km below ground?Regards,Chris 

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