A controversial gas extraction method caused two earthquakes in the UK last year, a government panel of experts reported. Yet, despite the environmental dangers fracking may cause, its resumption has been recommended, albeit under strict regulation.
The report by the Department of Energy and Climate Change (DECC) backs up an inquiry by energy company Cuadrilla late last year, after which the company admitted culpability for the small earthquakes which measured 2.3 and 1.5 on the "local magnitude" system under which three is classed as "moderate".
Gas drilling by Cuadrilla at the Preese Hall well in north-west England was suspended in 2011 after two earthquakes in Lancashire were felt at the surface.
Hydraulic fracturing or "fracking" involves pumping water, sand and chemicals into shale rock at very high pressures in order to release the reserves of natural gas which are stored within.