An earthquake with a magnitude of 2.9 has been recorded near the UK’s only active shale gas site in Lancashire.
The tremor near Blackpool is stronger than those that forced Cuadrilla to suspend test fracking operations in 2011.
The British Geological Survey recorded the earthquake at about 08:30 BST.
Cuadrilla said it was investigating the tremor and confirmed that no fracking was being carried out at the time or had been carried out over the weekend.
It follows another earthquake, with a magnitude of 2.1, measured at the Little Plumpton site on Saturday.
Government guidelines state any tremor measuring 0.5 or above means fracking must be temporarily stopped while tests are carried out.
The recent earthquakes are the largest recorded since operations resumed at the site last October.
Drilling was previously suspended in 2011 after earthquakes of 1.4 and 2.3 magnitude hit the area.
It resumed last year after campaigners failed in a bid to get an injunction.
People living nearby reported feeling the tremor.
Samantha Wheeler, who lives five miles away in St Annes, said her “wardrobe shook and her bed moved” when she felt the earthquake.
She said: “It’s getting really worrying.”
Fracking is the process of fracturing rocks with a high pressure mixture of water and chemicals to extract shale gas.
It has long been seen by the UK government as an important potential energy source.
However, the process of extracting unconventional gas in the UK has brought a flurry of protests and legal challenges.
What is fracking?
- Hydraulic fracturing, or fracking, is a technique to extract gas and oil from the earth
- Liquid is pumped underground at high pressure to fracture shale rock and release gas or oil within
- Applications have also been submitted by various firms in Yorkshire, Nottinghamshire and for a second site in Lancashire
- The Department for Business, Energy & Industrial Strategy says shale gas “has the potential to be a new domestic energy source”