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Is Geothermal Drilling A Potential Hazard?
News has recently surfaced that a 5.2 earthquake in the heart of Oklahoma was caused by drilling of waste water disposal wells that went some 1.5 miles underground. This apparently resulted in underwater channels opening up, cracks in the rock, and eventually slippage of an old fault line that had some tension but was rather stable before the water lubed up the fractures and produced a large earthquake. This and other stories have been made apparent lately, and with the USGS real-time plugin for Google Earth, you can easily tell that some areas doing deep drilling, hydrofracking, and geothermal prospecting do in fact affect seismicity in the areas that they are produced.
One such area that has a long history of this is Clear Lake/Geysers geothermal field in Northern California. This is one of the worlds largest producing geothermal operations, with more than 20 separate drill holes and facilities dotting the SW rim of the active volcano (it has not erupted in thousands of years, however hot springs, fumeroles, and seismicity indicate the presence of a large silicic magma chamber probably consisting of 'crystal mush'), the area is regularly host to about 20 small tremors in any given week, sometimes up to magnitude 4.0.
Other geothermal areas like Hengill in Iceland experience regular quake swarms as a result of geothermal prospecting.
The evidence for human meddling with fault lines goes back even as far as WWII, when a secret base in Hawaii called "Red Hill" was being constructed, engineers determined that dump trucks and other waste management vehicles would defeat the purpose of a hidden, underground base. So they did what they thought at the time was logical. Drill a gigantic, 1.4mi hole into the earth to dispose of waste products and be done with it. This ended up interacting with hot rock, and lubricating rock fractures, and before they knew it, they were getting many tremors per day, and were (disgustingly) forced to pump out thousands and thousands of gallons of polluted water to stop the quakes. Pretty nasty.
Today, with drilling 'en vogue' in the United States thanks to energy requirements, hydrofracking, waste water drilling, and geothermal prospecting are common nation wide. While industries would love to deny the facts, the facts can speak for themselves. Drilling massive holes in the earth, and pumping liquids into them, will affect the stability of the crust. Plain and simple. While most drilling produces seismicity that nobody notices (1.0 mag-3.0 mag quakes are barely able to be felt), sometimes, such as the 5.2 quake in Oklahoma, the quakes can be damaging and dangerous.
This will not stop industry from drilling these holes. The money is too good, and some of the resources are rare. But understanding the process might make one reconsider living around such a project, or at least, take the mystery and fear away as to "why are earthquakes happening in Oklahoma??". Human activity does affect our planet. It alters our forests, flora, fauna, and our geology. We can level mountains with reckless abandon, and mine our earth for precious and useful minerals... but we are only now realizing how much this can affect the earth's crust.