Cuadrilla has suspended fracking at Britain’s only shale gas exploration site after it recorded its biggest tremor yet.
Operations were paused for 18 hours after what it called a “micro seismic” event of magnitude 1.55 was detected at 8.46pm on Wednesday.
Work was halted several times last year due to minor tremors and it was only last week that Cuadrilla said it was resuming fracking at the Preston New Road site in Little Plumpton, near Blackpool in Lancashire.
The magnitude of the latest event was bigger than the previous largest recorded – at 1.5 – last December.
Cuadrilla said Wednesday’s tremor was only equivalent to “a large bag of shopping dropping to the floor” and that “most local people will not have felt it due to its small size”.
However it exceeds the UK threshold for fracking, under which exploration must be suspended if seismic activity with a magnitude of 0.5 or above is detected.
Cuadrilla has described the limit as “exceedingly low” and wants a review of the rules, which are much tougher than in the US.
In a statement on the latest event, the company said: “The Preston New Road exploration site is the most regulated and monitored site in Europe and the systems in place are working as they should.
“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.
“All the relevant regulators were informed and we have verified that the well integrity is intact.”
Fracking, or hydraulic fracturing, involves injecting water and chemicals at high pressure to break up rock and extract gas.
However, it can cause tremors and is opposed by environmentalists who say it can also contaminate drinking water. Protests have been a regular fixture at the Lancashire site.
Cuadrilla has said that the current fracking work would be completed by the end of November and then followed by flow testing of the well, with the results expected early in 2020.
It hopes its exploratory tests will show the potential of shale gas for the UK – and has said around 1,300 trillion cubic feet of gas is estimated to be contained in the area.
The government says shale gas could be an important new domestic energy source reducing dependency on imports as well as delivering economic benefits.