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Comment by Mac Davis on June 21, 2009 at 6:55

Re: "My understnding (which isn't always spot on) is that earthquakes result from the tectonic plates shifting. Are there instances of earthquakes occuring from formations expanding and/or collapsing?"

Earthquakes are caused by movements between sections of rock deep under the earth. It is not always between two "plates". It's a bit of a question of semantics. Not all faults are at plate boundaries.

The New Madrid earthquake of 1811 near St. Louis was a very major (estimated 8.0) earthquake in the middle of a tectonic plate.

The crust of the earth is not made up of discrete, solid plates that move with respect to each other. Think about rocks you've seen. There are major cracks, minor cracks, weak spots, sharp boundaries between different types of rocks, gradual transitions between one section and another, etc. Even in the middle of a "solid" chunk of rock, there may be cracks or weak spots. Rock is somewhat plastic on the scale that matters to earthquakes and geology. A former fault may "heal" and never move again. A spot that's never faulted before may crack under stress and form a new fault.

As to "expanding or collapsing," rock usually doesn't collapse or expand rapidly, but it can slip rapidly. The only thing it can do rapidly is slip along a fault, either an old fault or a new fault. If you have 1 cubic mile of rock before a quake, you have about 1 cubic mile of rock after the quake. The rock is still there, it's just been reshaped and moved.

There are no large caves or voids deep under the earth for rock strata to collapse into. Things are somewhat different if there are magma chambers in the area. Even then, it's sort of a slip rather than a "collapse", but it can be much more rapid because one component that's slipping is liquid. The magma has to go somewhere.

Consider what happens when you frack a well. Imagine the fracking zone as a cylinder 1 mile long, and 100 feet in diameter 10,000 feet underground. Imagine you crumble this entire zone into chunks of rock the size of grains of sand. There's no place for the fracked material to go.

The only case where you would have something major happen would be if there is already a fault near the frack zone, and the fault is about ready to slip anyway.

In that case, has fracking caused the earthquake or simply made it happen a little earlier? If it makes it happen earlier, is that a bad thing? Presumably, the longer you wait to relieve the stress, the stronger the eventual quake will be.

Also, realize that, in contrast to a fault, which is a plane between rock sections, a frack zone is sort of a line. It doesn't extend far from the well bore.

Comment by sesport on June 17, 2009 at 3:13

That also reminds me of the time we had the "Great Ice Jam," on the river, like the Arctic sae breaking up in spring. Never say never. lol

Comment by sesport on June 17, 2009 at 3:10

Keith - If you only knew some of the things people have been caught doing down by those banks. Were I down there when it happened, I'd be running backwards. :0)

Comment by Keith Mauck (Site Publisher) on June 17, 2009 at 2:21

Yeah Sesport, you better quit sun bathing off the banks of the red river

Comment by sesport on June 14, 2009 at 16:14

I'll stick my neck out here and suggest there may be some validity to whatever anecdotal records there may be from 1812 re. the Mississippi running backwards given what we know about the very low tides that occur during a tsunami. Heck, I'd run backwards, too, to get away from any natural disaster like that! lol

I can imagine being on one of those Thai beaches, hanging around, bartering with the locals to catch a boat out to the islands, when a wall of water comes at you. YIKES!!!!!

Comment by herefordsnshale on June 14, 2009 at 12:24

Isn't there a fault line in East Texas, somewhere around Cherokee County? I remember discussing it back in college but my memory is foggy. (20 years ago!)

Comment by mary on June 14, 2009 at 11:11

I just read an article on Yahoo News about fracing and earthquakes in Tx. The article was written by Jeff Carlton, Associated Press. I tried to look up info on Carlton and was led to a link for wind and solar alternative energy. Anyone else have information as to whether he has an agenda?

Comment by sesport on June 13, 2009 at 17:30

As Mrs. C would say .... "Ratzzzzz!" I forgot links don't work on blog comments. :0P

Comment by sesport on June 13, 2009 at 17:28

I'm not sure about Snake's assertion, but i did find that NexTag has it on sale for a song. lol

http://www.merriam-webster.com/dictionary/devolve

best - :0)

Comment by sesport on June 13, 2009 at 4:33

I would ask what the difference would be between the psi of frac'ing vs. tectonic shift, oh wise but now deposed GHS GD great one? LOL but, seriously, too :0)

I've got a nice, cold glass of clean water right here, as I see it half full. Can't "fault" me for that!

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