The fears of earthquakes and water contamination are being wildly exaggerated by all those who would prevent the hydraulic fracturing (fracking) of the vast deposits of gas shale available around the world. But research at the University of Durham puts the threat of micro-seismsity into perspective.
New research suggests that fracking is not a significant cause of earthquakes that can be felt on the surface. UK scientists looked at quakes caused by human activity ranging from mining to oil drilling; only three could be attributed to hydraulic fracturing.
Most fracking events released the same amount of energy as jumping off a ladder, the Durham-based team said. They argue that the integrity of well bores drilled for fracking is of much greater concern.
The research is published in the Journal of Marine and Petroleum Geology.
…. Fracking, as it is called, utilises a mixture of water, sand and chemicals pumped underground at high pressure to crack open sedimentary rocks and release the fuels within. But opponents of fracking have long been concerned that the process could induce earthquakes such as the one that occurred near a shale gas operation in Lancashire in 2011.
Now researchers from Durham University’s Energy Institute say that the pumping of fracking liquid does indeed have the potential to reactivate dormant fault lines. But they say that compared to many other human activities such as mining or filling reservoirs with water, fracking is not a significant source of tremors that can be felt on the surface.
“We’ve looked at 198 published examples of induced seismicity since 1929,” Prof Richard Davies from Durham told BBC News. “Hydraulic fracturing is not really in the premier league for causing felt seismicity. Fundamentally it is is never going to be as important as mining or filling dams which involve far greater volumes of fluid.” The researchers detailed just three incidences of earthquakes created by fracking – one each in the US, the UK and Canada. The biggest at Horn River Basin in Canada in 2011 had a magnitude of 3.8.
“Most fracking related events release a negligible amount of energy roughly equivalent to, or even less than someone jumping off a ladder onto the floor,” said Prof Davies. …..