Regulation

Amber-level tremor while fracking at Cuadrilla’s shale site

181023 pnr Eddie Thornton

Fence art at Cuadrilla’s Preston New Road fracking site near Blackpool, 23 October 2018. Photo: Eddie Thornton

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.

181023 BGS chart

Extract of British Geological Survey list of seismic activity in the UK showing most recent event in Blackpool

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.

181023 location map

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.”

59 replies »

  1. A slight TREMOR, which is as expected. If something is being fractured then quite normal. Monitoring system seems to be working well currently.

    Would be more worrying if no sign of anything being fractured. Then there would be cries of the operators not achieving what they set out to do.

    • Intelligent discussion with education people has resulted in me concluding tremors, earthquakes and seismic events are all the same thing!
      Any problems please refer to an educated person not the Sunday newspaperso.

    • Martin
      Nothing much to do here other than watch it pan out.
      I expect 0.5 to be exceeded at some time during or post fracking.
      But will there be one that can be felt (>2), we shall see no doubt?
      Ie will the expected ( or foretold ) by many ‘big one’ turn up?

  2. Thank you David , I read that , a great piece of work . I imagine this is the worst possible scenario for Cantdrilla , they cant stop but they cant carry on at levels required to do the job. After all this time I cant say im upset for Franny Egan .

    • Im sure that if it was expected then Cuadrilla wouldn’t be sailing so close to the wind already . Another shut down will cost them dearly and I doubt that when the tremor that does stop play comes I doubt it will be just 0.5

    • Ellie Gold
      While I agree that the Cuadrilla Portal is not as comprehensive a place to get information from than the BGS Site, I do not see that the company have failed to monitor the seismicity, be it before, during and after a fracking.

      Now … do the regulations state that their portal should include tremors after fracking has finished for the day, and any that occur before ( although before and after in terms of daily fracking look the same due to the short timescale)?

      Hence, while the portal could be a lot better by including all seismic events, I do not see that they have failed in their duty to monitor the seismic activity, and hence take appropriate action at the various trigger levels.

      Maybe a bit early to accuse the company of a breach of their frack plan, and hence a breach of regulation?

      • Hewes as far as I can ascertain the regulations allow the operator to devise their own HFP for approval, so if I am reading it right Cuadrilla designed their flow chart to exclude trailing events <0.5 whereas Third Energy devised theirs in a way which would include them. Both apparently acceptable to the OGA.

        What is questionable here is that Cuadrilla's HFP clearly states that their micro-seismic monitoring on which the TLS is based will continue for an hour after pumping, and yet they excluded the 0.3 Ml event which the EA say occurred just 15 minutes after. I am not a 17th century Jesuit priest so I don't quite understand their logic here.

        • Refracktion
          I think that they should pop all information on their portal rather than it being a selective scorecard.
          The key issue for OGA I assume would be that they follow their flow chart in terms of appropriate actions to take when fracking, in light of the micro-seismic information they have.

          Interesting that TE seem to be more pro active, but it may be down to which sub contractor is fracking.

          I doubt they stop looking at the data once fracking for the day is over, but once fracking has stopped, there is less scope for action should an event occur I guess ( ie Stop Pumping ).

          Mind you, if this was the pit, the local bag artist would have produced a cartoon showing Cuadrilla personnel eating donuts and drinking coffee, while watching Strictly … while behind them the seismic monitors were going up in smoke ( or quivering in the red ).

          A bag artist was a worker, good at cartoons, who drew on the large paper bags which had replaced sandbags. Mainly to lampoon management.

          • I agree they should publish it all. Their background seismic tab is incredibly selective as well with about 80 events missing from it and just 18 plotted. Quite bizarre!

            It’s not just about openness on the portal though – the question is whether there is a loophole in their system for events < 0.5 which occur within an hour of pumping.

  3. ““If 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….” Frack Free United (possibly not Premier League??)

    I thought the Permitted Development being considered excluded fracking? It says this in the article. It only covers drilling shale exploration wells for geological data – strat wells? So no tremors for PD wells.

    Note I am also against PD for any O & G wells but the discussion must be based on what is actually proposed.

    • Unfortunately, according to the Infrastructure Act definition, the volume of fluid used defines whether it is fracking or not. Keep below the defined limits and it’s not fracking. That’s the problem with using weasel words in place of clear, unambiguous definitions such as ‘the fracturing of rock using fluid at high pressure’. To my knowledge, and that of the expert minerals planner I discussed it with, the criteria for PD around shale gas exploration have not yet been formulated, so who knows precisely what will get popped into the regulations, other than those invited to secret round table meetings?

  4. These may be only slight earth tremors, but the area around Blackpool, was never an area, where coal mining occurred. Unlike other areas in Lancashire, Derbyshire and Yorkshire, which were heavily mined for coal. If ‘fracking’ is allowed in areas already riddled with coal mines, we could see some earth tremors of a higher magnitude!

    • Patrick
      Prof Styles thinks that there may be more events which trigger an amber event rather than tremors of higher magnitude if I remember correctly.
      Maybe there will be less, as many faults have been thoroughly de stressed by mining.

    • Please check with Prof David Smythe and you will find that the land around the Fylde is host to several natural faults augmented by the effects of the multiple earthquakes that stopped Cuadrilla last time they visited the Fylde.

        • Hewes62, I would suggest that irregular, unexplored natural faults are likely to be more hazardous to frack than man made tunnels, mapped and of exact known depth and location.
          Time will tell anyway.

          • Peter Roberts
            I agree that minevworkings will not cause more issues when fracked beneath. On a DOD there have been concerns raised over time that fracking in mined areas could cause subsidence, sink holes and major quakes, due to the presence of the workings rather than them being fracked ( as they are not fracked of course, being above the shale. ). And I agree that time will tell.

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