fracking caused the earthquakes.

magnitude-2.3 earthquake occurred on 1 April, followed by a magnitude-1.5 quake on 27 May.

Preese Hall drilling site

Cuadrilla Resources was using fracking to extract gas from a shale bed.

(BGS) suggested that the quakes were linked to Cuadrilla's fracking activities.

link with fracking has now been confirmed by an independent report commissioned by Cuadrilla, Geomechanical Study of Bowland Shale Seismicity

induced by direct injection of fluid into the fault zone."

two geologists

fracking could – and most likely did – provoke the quakes.

injecting huge volumes of water into the rocks surrounding a natural gas deposit

water fractures the rocks, creating dozens of cracks through which the gas can escape to the surface.

UK quakes were not caused by the violent rupturing of the rocks

water

lubricates the rocks and pushes them apart, allowing them to slip past each other

oiling the fault," says Brian Baptie of the BGS.

Fracking has been going on in the US for decades

become much more common in recent years

evidence

causes earthquakes

"This is one of the first times felt earthquakes have been associated with fracking," Baptie says.

Cuadrilla report says the earthquakes occurred because of a rare combination of circumstances

fault was already under stress

brittle enough to fracture and had space for large amounts of water that could lubricate it.

unlikely to happen again

small faults are probably common in deep rocks

given the same injection scheme in the same well, that there could be further earthquakes," he says.

If earthquakes begin to occur, it could reduce the flow of water into the well, or even pump it back out, preventing the bigger quakes.

damage