The risk of fracking increasing the risk of earthquakes in general, and "economically" significant earthquakes in particular, appears not to be an issue. Rigzone has a 4-page (internet) posting on studies linking earthquakes and fracking.
About half a million earthquakes are thought to occur around the world annually. However, the majority of earthquakes are too small to be perceptible; only about one in five earthquakes can be felt, and the rest can be detected only by sensitive instruments.
In the United States, there are recognized areas along fault lines where earthquakes occur with some frequency. There are also areas, such as the state of Texas, where earthquakes large enough to be perceptible are relatively rare. The link between fracking and earthquakes is indirect.
The most common method of fracking in use today typically involves the use of a mixture made of sand, chemicals and water that is injected at high pressure into the surrounding rock. The amount of water used can vary with each well, but a typical well in the Eagle Ford might use 7 million gallons of water, according to the Texas Water Development Board.
When a well has been hydraulically fractured, about 20 percent of the water used returns to the surface, according to the Ohio Department of Natural Resources. This water, which is called flowback or produced water, must be disposed of.
It is the process of injecting this water into the underground storage wells, and not the actual fracking of the well, that is most often linked to earthquakes.Related posts:
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