Fracking has been halted at UK’s only shale gas exploration site after it triggered the largest earthquake caused by the practice to date, according to an energy firm.
Operations were paused for 18 hours from Wednesday evening while Cuadrilla monitored the site near Blackpool after a “micro seismic event” with a magnitude of 1.55.
Most people who live near the site would not have felt the movement, which a spokesman for the firm claimed would have felt similar to someone dropping a large bag of shopping on the floor.
“Minor movements of this level are to be expected and are way below anything that can cause harm or damage to anyone or their property,” according to the spokesperson who said the “integrity” of the Preston New Road site had been confirmed by regulators.
The tremor was detected at 8.46pm on Wednesday, which was after the company had finished its fracking operations for the day.
The shutdown came less than one week after the energy firm started fracking a new well on the site after closing down the first one following a string of tremors.
Previously the largest tremor caused by fracking was a 1.5-magnitude quake recorded at Cuadrilla’s site at Little Plumpton in December.
Both are considered red events under the traffic light system for monitoring seismic events during fracking – pausing work for 18 hours is the routine response for any tremor over 0.5 magnitude. This provision has repeatedly brought operations in Lancashire to a halt.
The limit was set as a precautionary approach after two sizeable earthquakes struck at a Cuadrilla site near Blackpool in 2011.
In the US, which has a far more developed fracking industry, the limits are at between 2.7 and 4.5 depending on the state and Cuadrilla has repeatedly called for looser earthquake restrictions.
While smaller quakes are not generally felt at the surface, there are concerns repeated events will cause damage to infrastructure, and that they could lead to large tremors that compromise the fracking borehole and cause leaks.
A spokesperson for Frack Free Lancashire said: “We deplore Cuadrilla’s attempts to downplay and trivialise these quakes by making facile comparisons with milkshakes and bags of shopping being dropped.
“This is a serious issue and we know that seismic activity at similar levels deformed the well bore at Preese Hall, which Cuadrilla failed to report to the relevant authorities for six months.”
Fracking, in which liquid is pumped at high pressure deep underground to fracture rock and release gas, has proved controversial in the UK.
Ministers have presented shale gas as a relatively clean fuel compared to coal. They say investing in fracking is vital to ensure the UK has a reliable supply of gas, which will act as a relatively clean “bridge fuel” as the country transitions to a green energy future.
Backers, including the government, claim exploiting the fossil fuel could reduce reliance on imports, secure supplies, help cut carbon emissions and create jobs.
A government spokesperson said: “Shale gas could be an important new domestic energy source, reducing the level of gas imports while delivering broad economic benefits, including through the creation of well-paid, quality jobs.”
But opponents say fracking can cause earthquakes, damage the countryside and keep the UK hooked on fossil fuels instead of focusing on renewables to help tackle climate change.
Green groups say investing in further gas extraction will go against the warnings by climate scientists that fossil fuels must be eliminated as soon as possible.
Jamie Peters, campaigner at Friends of the Earth, said: “It’s obvious that fracking can’t be done without triggering earthquakes. Even small vibrations at ground level can be the sign of far more damaging impacts deep underground.”
“Fracking just isn’t part of the future if the government is serious about avoiding climate breakdown, in fact it defies belief that the oil and gas industry think they are part of a response to climate change.”
Earlier this month a study found there may be a lot less shale gas in the UK than previously thought – and fracking may only yield 10 years’ worth of fuel. This is five times less than 2013 estimates of 50 years’ worth, according to analysis of Bowland Shale Formation in north England.
Study author Dr Christopher Vane, head of organic geochemistry at the BGS, said the research “transforms our view of UK shale gas reserves”.
“This cutting-edge science shows that shales within the Bowland Formation could potentially contain less recoverable gas than previously thought,” he said.
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