http://geology.asu.edu
It's 3D geophysics. Of course, I don't understand any of it, but it's pretty cool. The Web address is long and complicated, but if you go to geology.asu.edu and poke around long enough, you should be able to find them.
http://www.azcentral.com/news/columns/articles/0902clay02.html
Does this mean we'd sag faster?
Sept. 2, 2004 12:00 AM
In the course of finding the answer to today's question, I came across some really cool maps of Arizona, which, as you drag the cursor over them, go from showing geology to measurements of gravity to depth-to-bedrock to magnetic.
It's 3D geophysics. Of course, I don't understand any of it, but it's pretty cool. The Web address is long and complicated, but if you go to geology.asu.edu and poke around long enough, you should be able to find them.
Anyway, this is the question:
Is it true that the strength of gravity is greater in some parts of the world than it is in others?
Yes, as a matter of fact, that is true. That's kind of weird, don't you think?
OK, for starters, the average strength of the Earth's gravitational field is about 980 galileos, or gals. Actually, that's the Earth's gravitational acceleration, the speed at which an object accelerates as it falls. Don't ask me what a galileo is. It's quite a bit.
I mostly threw that part in to try to sound smart, but also to point out that if you know what you're doing, it is possible to detect variations in the gravity field by measuring gravitational acceleration at various points around the globe.
Now a big part of determining the strength of gravity is mass, and that's why gravity varies around the globe - because the Earth's mass is unevenly distributed.
If you are up on the Colorado Plateau, where the Earth's crust is very, very thick, the gravitational pull is stronger than, say, down here in the Valley. It's not a lot stronger, as these things go, but scientists with the right equipment can tell the difference.
If, on the other hand, you were someplace on the globe with a lot of water under the surface or maybe just big empty spaces down there, the gravity would be different than it is on the plateau.
Anyway, people who know about such things can use gravity mapping to look for oil or mineral deposits, or study ground water levels and stuff like that. Or they study how earthquakes shift stuff around.
In some cases, the differences in gravity are significant enough to be noticed from space. A satellite might shift a bit in its orbit as it passes over areas where the pull of gravity is weaker or stronger.
OK, this is what a galileo is: It's 1 centimeter per second squared. Don't ask me why. It just is.
Reach Thompson at clay.thompson@arizonarepublic.com or (602) 444-8612.