Fracking ‘not significant’ in causing earthquakes

10 April 2013
By Edd Gent
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A study has found almost all earthquakes caused by fracking are so small only geoscientists are able to detect them

A study has found almost all earthquakes caused by fracking are so small only geoscientists are able to detect them

Fracking is “not significant” in causing earthquakes according to a new study led by Durham University.

The research by the Durham Energy Institute found that almost all of the seismic activity resulting from the controversial natural gas extraction process of hydraulic fracturing, commonly referred to as fracking, was on such a small scale that only geoscientists would be able to detect it.

The team also discovered the size and number of felt earthquakes caused by fracking is low compared to other manmade triggers such as mining, geothermal activity or reservoir water storage.

But the study also established beyond doubt that fracking has the potential to reactivate dormant faults and described the probable ways in which the pumping of fracking fluid underground triggers this.

Professor Richard Davies from the Durham Energy Institute says: “We have examined not just fracking-related occurrences but all induced earthquakes, that is, those caused by human activity, since 1929.

“It is worth bearing in mind that other industrial-scale processes can trigger earthquakes including mining, filling reservoirs with water and the production of oil and gas. Even one of our cleanest forms of energy, geothermal, has some form in this respect.

“In almost all cases, the seismic events caused by hydraulic fracturing have been undetectable other than by geoscientists. It is also low compared to other manmade triggers.

“Earthquakes caused by mining can range from a magnitude of 1.6 to 5.6, reservoir-filling from 2.0 to 7.9 and waste disposal from 2.0 to 5.7.

“By comparison, 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.

“Of the three fracking-related quakes that could be felt, even the largest ever, in the Horn River Basin in Canada in 2011 had a magnitude of only 3.8. That is at the lower end of the range that could be felt by people. The widely-reported quake at Preese Hall near Blackpool in 2011 had a magnitude of 2.3.

“So we have concluded that hydraulic fracturing is not a significant mechanism for inducing felt earthquakes. It is extremely unlikely that any of us will ever be able to feel an earthquake caused by fracking.

“But theoretically, it cannot be ruled out completely; we cannot see every fault underground and therefore cannot completely discount the possibility of the process causing a small felt earthquake.

“But there are ways to further mitigate against the possibility; the oil and gas industry can avoid faults that are critically stressed and already near breaking point. We hope our analysis can help provide important context and inform the current debate on this.”

The research entitled “Induced Seismicity and the Hydraulic Fracturing of Low Permeability Sedimentary Rocks” is published in the Journal of Marine and Petroleum Geology.

But Greenpeace energy campaigner Lawrence Carter is keen to stress that this research does not invalidate the opposition to the controversial process.

“People’s apprehensions about fracking go well beyond earth tremors – communities are concerned about the industrialisation of the English countryside, including noise, increased traffic, falling house prices and environmental damage,” he says.

“Documents obtained by Greenpeace reveal the Environment Agency’s private fears over threats to drinking water near potential fracking sites in Sussex. While in the US, the release of climate change gases around fracking sites has been found to be so high that shale gas could end up being as polluting as coal.

“Everyone from Ofgem to BP agree UK shale gas won’t bring down bills, so fracking could end up being a lot of pain for very little gain. Instead we need to move towards a carbon free electricity system, which will be cleaner, safer and cheaper over time.”

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