Hydraulic Fracturing (or Fracking) is a method used to extract natural gas from shale rock formations in which it is trapped. Engineers drill a hole deep into the rock, and then inject a mixture of sand, water and chemicals into the hole at an extremely high pressure. This causes the rock to split, releasing the gas into the well.
Fracking has been linked to a variety of environmental concerns including the contamination of groundwater supplies, air pollution and seismic activity. One major recently published report found that the risk of water sources being contaminated was no higher with fracking than other drilling processes, and that most pollution was due to mistakes of operators.
But another study recently claimed that emissions released into the atmosphere could cause headaches and breathing problems in people living up to half a mile away.
The Blackpool earthquake was the first direct evidence of fracking causing seismic activity, but the report's authors argue there is only a minimal risk of a tremor big enough to damage any buildings or people.
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