Seismic events at fracking site

A series of seismic events close to Cuadrilla’s Blackpool site has been recorded shortly after it began the first fracking in the UK since 2011.

A tremor of 0.3 on the Richter scale (ML) was recorded by the British Geological Survey at 1.20pm on Friday.

That would place it in the amber light zone for Oil and Gas Authority fracking regulations if the company had been hydraulically injecting for gas at the time.

Amber light regulations state that fracking can proceed “with caution, possibly at reduced rates. Monitoring is intensified”.

Tremors above 0.5ML mean the injection of water and chemicals to release shale gas – fracking – is suspended immediately.

But the company said that as it was not pumping liquids at the time of the event, it was not required to change its operations.

Cuadrilla began fracking on Thursday for the first time since earthquakes forced a halt in 2011 and a change in the regulatory regime. It won its license in July.

The government and fracking industry executives insist the permitted levels of seismic activity are on the conservative side for safety.

The Friday afternoon tremor follows three seismic events near Cuadrilla’s Preston New Road site on Thursday. These were on the minus Richter scale.

A British Geological Survey spokesperson said the three smaller events were so small they would not have been felt and that if they were related to fracking they are well within the threshold of safe operations.

But David Smythe, emeritus professor of geophysics at Glasgow University, said: “I said earlier today, after the three tremors of yesterday, that there may be trouble ahead, because Stanford University research suggests that tiny tremors caused by fracking are a precursor to bigger events.

“Well, here we are, with a magnitude of 0.3ML today, an order of magnitude in amplitude of ground motion larger than those of yesterday.

“If Cuadrilla carries on it is likely, in my view, to trigger bigger events. An event of just twice today’s amplitude will be enough to trigger the red alert to stop fracking.”

Cuadrilla said the Thursday events were not of concern. Earlier this month it began publishing its daily seismicity data on its website.|

“We’ve been monitoring baseline seismicity for some time in the run-up to starting hydraulic fracturing operations, and we have noted fluctuations at this very low level of micro-seismicity – that is, at minus levels – during that time before we started hydraulic fracturing,” said a Cuadrilla spokesperson.

“What we do know is that our detection systems are working as planned and these very low levels of seismicity are being detected.

“We take the monitoring and regulation of seismicity seriously, with daily reports sent to the regulators. The micro-seismic events recorded [on Thursday] were extremely low and well within the green light threshold of the traffic light monitoring scheme regulated by the Oil and Gas Authority.”

“Considering the relevant past history all eyes are currently on Cuadrilla.”

Regarding the larger tremor on Friday afternoon, the spokesperson said the company was not fracking at that time and that “therefore this was simply another low level micro seismic event”.

Surface-felt earthquakes are generally greater than 2ML. The BGS recorded earthquakes up to 2.3ML at Cuadrilla’s nearby Preese Hall site in 2011.

A spokesperson from Frack Free Lancashire said: “We will continue to monitor these events closely. Considering the relevant past history with the Fylde Coast’s geology and having two significant seismic events which effectively shut down the fracking industry, all eyes are currently on Cuadrilla.

“These events may be dismissed as being minor and ‘can’t be felt’ but what occurs under the earth is beyond anyone’s control.”

Earlier in the week, three fracking protesters were released from jail after an appeal court ruled their sentences for protesting at Preston New Road were “manifestly excessive”.

This article was changed to make clear that seismic events only fall into the OGA traffic light regulation scheme if they occurred when fracking was actually taking place at that moment. 

Read more of our fracking coverage at bigissuenorth.com/search/fracking/

Main photo: Getty Images