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Gravity Map of Earth
dr3vil writes "Interesting results have been published by the GRACE (Gravity Recovery and Climate Experiment) project, of the various gravity anomolies that exist at various places on Earth. The BBC report gives a good overview. Fascinating for me, a resident of California, to see us apparently sandwiched between a high and a low spot. Maybe that helps aids the tectonic flows around here?"
BTW, if you want to know how much gravity differs (and how damn sensitive these sats are), look at this chart:
/ 03 _07_GRACE.html
http://www.csr.utexas.edu/grace/gallery/gravity
And note the range of the legend -60 to +60 mGal.
Because variations in gravity are very small, units for gravity surveys are generally
in milligals (mgal) where 1 mgal is one thousandth of 1cm/s
Thats damn sensitive.
-molo
Using your sig line to advertise for friends is lame.
Maybe that helps aids the tectonic flows around here?
Seems to me that the techtonic flows cause, rather than are caused by gravitational differences. Less mass in one area == less gravity, and so forth.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. (Einstein)
Can't work. Basically you are measuring the denisty/mass differences in large areas (lets even say you can do it down to the centimeter though). So an area that has high mountains, highly dense subsurface is going to have a higher pull from gravity.
A submarine with neutral boyancy (not going up or down, just level) would displace an equivalent volume of water, therefor not change the gravity field around it.
That said, there is no reason why we can't us other things like detecting the change in magnetic flows because a large nuclear reactor just went underneath, and things like that
I have mod points and I am not afraid to use them
If the sub is moving, their is a layer of compressed water on one side, and a layer of slightly less compressed water on the other side (kind of like how radar sees a moving volume). Not to mention any bubbles generated by the spinning prop(s) out back decreasing the density of the water significantly. Question is; can we detect it fast enough to matter? Knowing where a sub was 30min ago is useless.
IIRC, magnetic harmony has already been reached between sub and ocean. I think that was something they did back in the 50's or 60's. Not 100% on that though...