Fact/Fiction: Should we be scared of fracking earthquakes?

How it was told

Almost as soon as fracking had begun for the first time in seven years in Lancashire, Cuadrilla were forced to down tools for 18 hours because of an earthquake.

That triggered headlines of “Fracking halted by ANOTHER earthquake” in the Daily Mail while The Guardian reported that “Strongest tremor yet halts fracking at Cuadrilla site.”

Each time a tremor over 0.5 magnitude is recorded, fracking stops at the Preston New Road site in Lancashire.

The seismic activity has triggered debate, with The Guardian reporting “Government faces new legal challenge over plans to speed up fracking” after Greg Clark, the Business Secretary, told local authorities of loosening planning regulations.

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But the protestors still insist that the controversial shale gas extraction process poses a threat, as reported by the Lancashire Evening Post in “36th tremor prompts new calls from five Lancashire MPs to halt fracking.”

Frack Free Lancashire’s Claire Stephenson told the LEP: “Preston New Road is a complete experiment, and one which we are having to live with the consequences – both known and unknown.”

Facts. Checked.

The truth is that fracking does cause earthquakes. Considering that the process behind it involves water, sand and chemicals being injected at high pressure into underground boreholes to crack open rock it’s hardly a surprise.

Since drilling commenced in Lancashire on October 18, the British Geological Society (BGS) has recorded 36 mini-earthquakes in Blackpool. They have ranged from a magnitude -0.8 – virtually imperceptible – to 1.1, which was felt by people in nearby Blackpool. Only four quakes topped the 0.5 threshold – which is akin to a passing car – and forced Cuadrilla to halt operations.

But they are not even the strongest out of the last 100 earthquakes felt in the UK, with a 3.1 magnitude quake recorded in Newton Aycliffe, County Durham in September far exceeding anything felt in Blackpool.

In fact, the 1.1 levels reached in Lancashire are 100 million times smaller than the 9.1-magnitude quake that triggered the Boxing Day tsunami that killed 227,900 people across South Asia in 2004.

There are a few hundred quakes in the UK that are only felt by seismic instruments every year, according to BGS, with only 20 or 30 registering with people. However, the glut of seismic activity in Blackpool could be put down to the BGS, who have installed extremely delicate sensors in the area, while equipment in the rest of the UK typically can only detect earthquakes with magnitudes of two or above.

But do they hold the potential to trigger bigger quakes? Dr Stephen Hicks,  Seismology expert at the University of Southampton, told Full Fact that there have almost certainly been incidents when fracking triggered earthquakes in existing geological faults. But it’s difficult to predict when fracking might trigger earthquakes because existing faultlines in subterranean rock haven’t yet been completely imaged.

Public Health England have evaluated available evidence on issues including air quality, radon gas, naturally occurring radioactive materials, water contamination and waste water. They concluded that “The risks to public health from exposure to emissions from shale gas extraction are low if operations are properly run and regulated.”

Fracking is by no means the only activity that can cause tremors – underground mining, impoundment of deep artificial water reservoirs and geothermal power generation can have an impact too.

With thanks to fullfact.org

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Illustration: Miles Cole

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