Location of seismic events linked to fracking at Cuadrilla’s Preston New Road site near Blackpool. Activity today is marked with red rings. Source: Batchgeo using Google Maps

The British Geological Survey has reported a 0.5 magnitude earth tremor this afternoon near Cuadrilla’s fracking site on the edge of Blackpool. There was also a 0.4M tremor and two micro-seismic events.

Although too small to notice on the ground, the 0.5M event is the largest so far in a series recorded near the site since fracking began earlier this month.

Cuadrilla said the 0.5M tremor did not count as a red seismic event under the government’s traffic light system for monitoring seismicity. This would have required the company to stop fracking, carry out checks on the well and inform the regulators.

A Cuadrilla spokesperson told DrillOrDrop the event actually measured 0.48M and had been rounded-up by the British Geological Survey. He said the company was also not fracking at the time of the tremor. Fracking planned for tomorrow is expected to go ahead, he said.

The British Geological Survey record of UK earthquakes says magnitudes are calculated to one decimal place, which is standard practice in earthquake seismology.

A statement from Cuadrilla posted on Facebook said:

“Following on from hydraulic fracturing operations today Cuadrilla has detected micro seismic activity of 0.48ML. This is within the operating expectations and the sophisticated system of monitoring in place is working as it should. We understand that the British Geological Survey has rounded this up to 0.5ML. Regulators have been advised and we anticipate we will continue work at Preston New Road tomorrow as planned.

“As we have said before, 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 2km underground and are many hundreds of orders of magnitude below what is capable of being felt much less cause damage or harm at the surface.”

Yesterday, Cuadrilla stopped fracking for the day after a 0.4M earth tremor was recorded during operations at 3.45pm.

Today’s events mean 10 of the past 12 seismic events in the UK have been near the Preston New Road well.

The seismic activity began four days after fracking started at the site. There were micro-seismic events on 18 October, followed by a 0.3M tremor on 19 October. There was a 0.0 event on 20 October, 0.4 on 23 October and 0.5, 0.4, -0.2 and 0.0 today (24 October).

Cuadrilla’s hydraulic fracturing plan said if seismicity of 0.5M or more was recorded within a defined area during fracking then the company will flush the well, stop injection and reduce well pressure. It would also verify well integrity. Cuadrilla should report the incident without delay to the Oil & Gas Authority, Health and Safety Executive and Environment Agency.

The traffic light system for seismic monitoring was introduced after 2.3 and 1.5 earthquakes were linked to Cuadrilla’s fracking operation at Preese Hall, also near Blackpool, in 2011.

Cuadrilla’s area of operation for the Preston New Road well. The red zone marks where fracking can take place. Source: Cuadrilla Resources

A spokesperson for Frack Free Lancashire said:

“The escalating magnitude in tremors caused by fracking in Lancashire is unacceptable.

“Today, a 0.5 magnitude tremor occurred. Seismicity must be monitored closely around the clock if hydraulic fracturing is allowed to continue in spite of the cluster of tremors we have seen around the toe of Cuadrilla’s well.

“Local residents are rightly concerned by these events and the fact that the traffic light system has had to halt operation just a week into the process.

“The issue is not whether these events can be felt, but whether they could be precursors to similar events that occurred at Preese Hall in 2011, which led to Cuadrilla’s performance as a licencee being questioned by the then Energy Minister, Charles Hendry.”

“The well integrity and safety of what happens underground is beyond anyone’s control, following a seismic event. This risky technology employed by an inexperienced operator – as demonstrated by the seventh tremor in as many days, causing a Red warning on the Traffic Light System, is something residents will never support and our strong opposition will continue and increase.”

Richard Marshall, an anti-fracking campaigner at Preston New Road, said:

“Cuadrilla are claiming that the seismic events are low level and residents should be reassured that the monitoring equipment is doing its job.
We do not feel reassured and our fears have been realised. We also expected seismic events. We have been explaining and proving that there are fault lines in the area and that there is a great risk to well casings rupturing. It seems that Cuadrilla are insistent on progressing to appease their investors to the detriment of the health of the people.”