Wednesday, December 21, 2011
Arkansas earthquakes now tapping into high reservoir
If I were to be scientific, I would put infinite qualifications and question marks. But, what the hey, that's boring! Arkansas continues to bubble away, even though they stopped injecting quite a while ago. Now it is starting to look like Virginia, so I have great hope for another large earthquake! (Is that goulish?).
This lake is very deep (Greers Ferry Dam) well capable of inducing earthquakes. Why hasn't it done anything until now, since the dam was built in 1960? Once again, it is all rock mechanics, which is what I push on the deaf ears of seismology.
In order for water to start tickling a fault, you need permeability. In other words, you could have very tight rock, and not a drop of water gets to the fault to start the process of stress corrosion. These faults are at a very high stress, and not inclined to let water in. As well, you could have a tight cap rock like shale protecting the fault.
All this goes away the moment you inject tons of water to 10,000 feet or more. Every earthquake cracks more rock, and increases the permeability. If you are pig-headed enough to keep injecting, you can crack the rock to the 'point of no return', that is, it starts to capture other water sources.
At the time of my first observations, I was not aware of this lake and thought the conjugate set of faults would shed all earthquakes after they stopped injecting. Big Surprise! There is no stopping this thing now. It is like a big landslide, slowly gathering steam off the mountain.
This fault system will now start to grow into another New Madrid.
So now we have:
West Texas - M4 in the new year, for sure. They will never stop pumping.
Virginia - Had their M6, a long time for the M7
Ohio - they stopped pumping, probably dead.