“Highly probable” shale gas extraction caused earthquakes, Cuadrilla admits

The findings of the report have renewed calls from green groups to end fracking in the UK. The controversial method of gas extraction has been linked to air and water pollution and could endanger the expansion of clean, renewable energy if adopted properly in the UK. An earlier study by the British Geological Survey, also connected fracking to the two earth tremors that shook the Lancashire coastline earlier this year.

Cuadrilla downplayed today’s findings, however, saying the earth tremors were "unlikely" to occur again at future well sites. The report blamed the earthquakes, which measured up to 2.3 on the Richter scale, on "an unusual combination of geology at the well site coupled with the pressure exerted by water injection as part of operations".

Fracking is the process of injecting millions of gallons of water, sand and chemicals under high pressure, into deep natural gas wells. The pressure fractures the shale and props open fissures that enable natural gas to flow out of the well.

Those who support shale gas consider it a relatively clean, cheap form of energy. Cuadrilla says the creation of a shale gas industry in the UK would help lower rising energy bills and offers a substantial growth opportunity for the economy with its own operations alone potentially creating up 5,600 jobs.

However, shale gas detractors say it will trigger a 'dash for gas’ and suck vital investment away from green energies, while at the same time threatening the environment and human health. In, the US it has been blamed for setting tap water afire in homes, while a report by New York’s Cornell University claims that producing shale gas allows a greater amount of methane, a powerful greenhouse gas, to escape into the atmosphere than traditional gas extraction.

Describing the Cuadrilla findings as "worrying", Nick Molho, head of energy policy at WWF-UK said, "we’re extremely concerned by the way in which shale gas is being painted as a 'wonder gas’ which will slash energy bills in Britain and help tackle climate change".

Friends of the Earth’s senior climate campaigner Tony Bosworth added that "there should be no more fracking in Britain until the health and environmental impacts are fully understood."

The Cuaderilla report has been submitted to the Department of Energy and Climate Change, which will make a decision on whether to allow drilling to resume.