The British Geological Survey (BGS) has detected tremors in the vicinity of a controversial fracking operation in Lancashire.

Energy company Cuadrilla started hydraulic fracturing at the site in Little Plumpton, near Blackpool, earlier this week after an unsuccessful High Court appeal to block it.

In a statement, the BGS said that the seismic activity recorded at 2.20pm on Friday was "not unexpected", as hydraulic fracturing is "generally accompanied by microseismicity".

Image: Protesters have been keen to stop the work in Lancashire

A Cuadrilla spokesperson said the firm "was not fracking at the time the tremors were felt" - and that they were below the level that would require them to pause its work.

The magnitude recorded by the BGS on Friday was 0.3, while tremors felt on Thursday came in at -0.3 and -0.8.


Anything measuring zero or below is classified as "green", while recordings up to 0.5 are "amber", meaning fracking should proceed with caution.

Readings above 0.5 mean fracking should be suspended immediately.

"We share all of our data with the BGS and the tremors were not strong enough to have been felt at surface level," the company spokesperson added.

Cuadrilla's Francis Egan says the UK's demand for energy is not going away, as the company prepared to start fracking at its Preston New Road site in Lancashire

Earthquakes were also felt the last time fracking took place in the UK in 2011 - again in Lancashire - and the process had to be brought to a halt.

The latest operation - set to last three months - has already faced disruption due to bad weather and protests, with dozens of activists descending on the site on Monday to express their concerns about the environmental impact.

Cuadrilla has permission to operate between 8am and 6pm on weekdays, and 9am and 1pm on Saturdays.

The BGS said it had deployed additional surface seismic sensors to monitor across the North to coincide with the project, which will provide "an independent assessment" of whether any activity is natural or caused by the fracking.

All of the data collected by the sensors will be published on its website, the society said.