Fracking, or hydraulic fracturing, is a way of artificially stimulating oil and gas wells by forcing pressurized water underground into fossil fuel reservoirs. This fractures rock formations in these pockets, helping bring more hydrocarbons to the surface. The practice can also affect groundwater and the seismic stability of a region.
When an oil well is drilled into a deposit, it can only pump out the oil present in that void in the geologic structure. If there are cracks leading to other deposits, however, the oil can leak through and become available. Hydraulic fracturing creates a large series of cracks throughout a petroleum formation, allowing much more oil to flow into the drilled section. This allows the driller to pump considerably more oil without having to drill new wells.
Fracking uses large amounts of water to create these fractures, as well as chemical compounds designed to keep these fractures open and allow oil to flow through. One of the major concerns about fracking is the ability of this tainted water to make its way into the water table, possibly carrying oil and other hydrocarbons with it. In addition, the large numbers of fractures caused by the procedure can serve as fault lines, increasing the possibility of earthquakes and tremors in the area.