Fracking is a slang term used for the technique of hydraulic fracturing, in which liquids are forced into layers of rock to create and enlarge fractures for the purpose of extracting raw petroleum materials like oil and natural gas. Some experts and concerned citizens in areas where fracking is performed have claimed that it can cause earthquakes. This controversial practice has not been conclusively tied to seismic activity, but there is some evidence linking fracking and earthquakes. To what extent, if any, fracking contributes to tremors or other seismic events is unknown.
Earthquakes are caused by the movement of portions of the Earth's crust. This can cause great damage due to the shaking and shifting of buildings and other structures. Fracking is believed by some, including some experts in geology and seismology, to contribute to or even cause minor earthquakes. Fracking causes fractures in rock layers which can weaken them. These fractures can reduce the rock's stability and reduce its resistance to movement, particularly around fault lines. It is believed that this may cause rock layers that have been subjected to fracking to lose some of their structural integrity and to shift or break even more severely, causing earthquakes.
Evidence for a link between fracking and earthquakes is incomplete, but in more than one area where fracking has been practiced, a noted increase in earthquakes has been recorded. In Arkansas in the United States, for instance, two injection wells, which are wells used to inject liquids into rock layers as part of the fracking process had operations suspended in early 2011, pending further study, after more than 800 small earthquakes, one registering 4.8 on the Richter scale were recorded in the area around the wells.
A similar occurrence near a fracking operation in Great Britain in 2011 also caused a halt in an operation, pending further study. The increase in earthquakes, most, if not all, of which are classified as microquakes, or very slight tremors, in areas where fracking operations are undertaken is well documented. The mechanism by which fracking might cause these quakes is not understood nor has it been conclusively proven that such a direct link between fracking and earthquakes exists.
Many experts believe that fracking and the increase in earthquakes in the areas around large-scale fracking operations are related, but this has yet to be proven. A direct correlation between other human activities and earthquakes is well documented and is a main source of the belief that fracking and earthquakes may be related. Many industry experts as well as some independent experts insist, however, that there is no relation at all between fracking and earthquakes or that if tremors are a direct result of fracking, that they are minor and are not severe enough to be dangerous in the way that many naturally occurring earthquakes can be.