Cuadrilla has confirmed there was a 0.4 magnitude earth tremor while it was fracking at its Preston New Road shale gas site this afternoon.
This is an amber event under the seismic regulations, known as the traffic light system. At this level, operators should proceed at caution.
The company said it had stopped fracking for the day.
The tremor is the sixth in a week reported by the British Geological Survey in a series of seismic events near the fracking site.
The tremor measured only 0.4 magnitude and was too small to be felt at the surface. But it is the largest of the tremors so far. And it is the first that we know happened while fracking was taking place.
Under the seismic rules, fracturing should stop immediately if there is seismic activity measure 0.5M or more.
Cuadrilla told DrillOrDrop:
“The highly sensitive monitoring systems at and around Cuadrilla’s shale gas exploration site in Preston New Road have detected a seismic event within the company’s operational area (approx. 4.8km²) of 0.4 ML (Local Magnitude) this afternoon while hydraulic fracturing operations were ongoing.
“This is an extremely low level of seismicity, far below what could possibly be felt at the surface but classed as an amber event as part of the Traffic Light System (TLS) in place for monitoring operational activity. As such we are required to reduce the rate we are pumping fracturing fluid once it has been detected. In fact we have adopted extra caution and have stopped pumping for the day.
“Seismicity will, as always, continue to be monitored closely around the clock by ourselves and others and we plan to continue hydraulic fracturing again in the morning. Local residents should be reassured that the monitoring systems in place are working as they should. These are tiny seismic events that are being detected by our monitors as we fracture the shale rock and are not capable of being felt much less cause damage or harm.”
According to the BGS, six of the past eight seismic events reported in the UK have now been in the area around the end of the well where fracking began on 15 October 2018.
Today’s event was at 3.45pm (BST) in an area between the A583 and Peel Road. It follows a gap in recorded seismic activity in the area since 4.44am (BST) on Saturday (20 October 2018), when there was a 0.0M event.
Yellow rings mark location of six tremors up to the afternoon of 23 October 2018. Source: Googlemaps
The activity began last week on 18 October, when there were -0.2, -0.8 and -0.3 events. There was a single event on 19 October which measured 0.3.
Previous events had not been shown on the Cuadrilla online portal. The company said events at an amber level that occurred outside the fracturing operations were regarded as “trailing events” and would not be shown.
A spokesperson for Frack Free Lancashire said:
“Frack Free Lancashire is greatly concerned about these seismic events. It is most alarming for residents. Considering this is only the exploratory phase and only one frack a day imagine how much worse it could be.
“Who knows what is happening under our feet? This is the earth giving out a warning, as predicted by geologists following the previous failures of fracking in Lancashire. “The increased risk of larger magnitude quakes is serious. Cuadrilla must stop now, for all our sakes.”
A spokesperson for the campaign network Frack Free United said:
“To continue risks a larger ‘industry wrecking event’ , like Preese Hall 2.0. To stop just admits that they couldn’t see the fault before they started fracking. Its lose, lose, but experts have tried to mention the risks and safeguards.
“Permitted Development were to be allowed, with the present planning avoidance of seismic risk, there would be no way to stop these tremors before they happen. Yet it was only a week ago that we were told by Claire Perry, Natascha Engel and UKOOG that earthquakes are a non issue.”
A spokesperson for the pro-fracking campaign group, Lancashire For Shale, said:
“A 0.4 magnitude event like this is so small it is only possible to detect it using very sensitive instruments like those deployed locally by Cuadrilla and the British Geological Survey.
“The very open manner in which this event has been reported, and Cuadrilla’s reaction to it, demonstrates just how robust the new controls are and that the Traffic Light System is working effectively.”