Research

Fracking tremor limit could be raised safely, say scientists

pnr 181024 Eddie Thornton

Opponents of fracking at Cuadrilla’s Preston New Road site, 24 October 2018. Photo: Eddie Thornton

Two scientists have said the rules on fracking-induced earth tremors could be relaxed with little risk to people.

Under the current traffic light system, fracking must stop for 18 hours if the operation induces seismic activity of 0.5ML (local magnitude) or above.

Now Dr Brian Baptie, of the British Geological Survey (BGS), and Dr Ben Edwards, of Liverpool University, argued that the limit could be raised safely to 1.5ML, which, they said, was unlikely to be felt.

Their proposal, made in a media briefing earlier today, was welcomed by Cuadrilla, which triggered 57 earth tremors when it fracked in Lancashire last year.

But opponents of Cuadrilla’s operations said people were less concerned what was felt at the surface and more about what happened at the depth of the wellbore. Campaigners in Lancashire said they would consider a legal challenge if the government gave into industry lobbying for a higher limit.

Cuadrilla’s fracking operations at Preston New Road triggered three tremors which exceeded the 0.5ML red traffic light level during fracking last year. Another four passed the 0.5ML threshold after fracking had finished. Two of the tremors, measuring 1.1ML and 1.5ML were felt by people living and working locally.

The company previously called on the government to raise the 0.5ML threshold. It pointed to higher limits of 4ML in Canada and 2.7 in California.

But the energy minister, Claire Perry, has said there are no plans to relax the rules. In a letter to Cuadrilla in November 2018, she said the current system was “fit for purpose” and there was “no intention of altering it”. She repeated this position in a recent parliamentary answer.

181214 bubble chart refracktion

Seismic events at Cuadrilla’s Preston New Road shale gas site up to 14 December 2018. Source: Refracktion

Dr Brian Baptie, head of seismicity at the British Geological Survey, said today:

“The existing regulations are really quite conservative. They are set at a level of earthquake that is really very unlikely to be felt.

“So something like 1.5 is a level of earthquake that is not going to be felt widely by people – I think it is something we ought to have a look at.”

He said:

“When earthquakes occur, they cause shaking, so could that shaking damage the wells? I think the risk of that is vanishingly small – it is negligible for such small events”.

Dr Baptie contributed to a government-commissioned report on Cuadrilla’s earlier experience of fracking-induced seismic activity when its first frack at Preese Hall in 2011 prompted earthquakes measuring 2.3ML and1.5ML. That report recommended the current red traffic light of 0.5ML.

The other scientist, Dr Ben Edwards, has contributed to material for Cuadrilla and the government. He said:

“If you want to mitigate any chance of felt activity, similar in vibration magnitude to a building site, we have the correct traffic light system.

“But if you want to go to a risk-based approach, where you allow events that do not pose any risk to humans or structures, then there is scope to review the current system, that could be raised to 1.5 and that would still arguably be conservative.”

Dr Edwards was responsible for recent government-commissioned research which likened the effects at the surface of a 1.1ML tremor to a 1kg bag of flour falling to the floor, and a 1.5ML tremor to a dropped honeydew melon.

Frack Free Lancashire said this evening:

“It seems to have taken the industry spin doctors longer than expected to find a couple of academics prepared to make their case for them.

“However, both of these researchers still appear to be inexplicably fixated on whether a tremor can be felt at surface.

“The Traffic Light System (TLS) was devised, in conjunction with Cuadrilla themselves, to protect the public from the potential subsurface impacts of fracking. It is based on an acceptance that the seismic events (which fracking appears to inevitably unleash in the UK) cannot be constrained by turning off a tap, and that they may get progressively more frequent and larger after the warning level is exceeded and work is stopped.

“The government and local Conservative MP, Mark Menzies, have already stated their opposition to increasing the TLS limits. Claire Perry – the energy minister – stated that would be a “foolish politician who would do things that would be considered to be relaxing regulatory standards when we are trying to reassure people about safety.”

“If the government were seen to be caving in to industry lobbying after they have so clearly demonstrated that they are unable to control the seismic activity caused by their operations, we will consider seeking a legal challenge.”

John Sauven, executive of director of Greenpeace UK, said:

“This is a barely disguised attempt to mislead people. The main concern over tremors caused by fracking is not damage caused at the surface but damage caused to the well.

“This is likely to be near the epicentre of the quake. We know this is a risk. It is exactly what happened at the UK’s first fracked well at Preese Hall in 2011. The well bore damage was observed after quakes which caused no damage at the surface.”

A spokesperson for Cuadrilla said:

“We were pleased to hear this. We have collected an extensive data set from our operations at the shale gas exploration site in Preston New Road, Blackpool, including the most comprehensive micro-seismic data set ever collected at a shale site.

“We have shared this with the relevant regulators and experts to enable further understanding of how best to safely and effectively progress this important industry”.

51 replies »

  1. “We have shared this with the relevant regulators and experts to enable further understanding of how best to safely and effectively progress this important industry”.
    pointless; you cannot, so don’t waste more investors money…

    • Response by the BGS to Cuadrilla’s request for a new threshold. This request is months after the events at Preese Hall when flow testing should have been well underway.

      “The initial threshold for cessation of operations proposed was 1.7 ML. This was based on the critical magnitude 2.6 ML and a maximum post-injection magnitude increase of 0.9 ML. However, we note that, based on this limit, no action would have been taken before the
      magnitude 2.3 ML event on 1 April 2011. We recommend a threshold of 0.5 ML for cessation of operations, to minimise the probability of further felt earthquakes”

      Little frack, nothing back?

    • I think we can now safely presume that at a 0.5 magnitude threshold, fracking in the Bowland shale is not viable.

      • I think that most people with knowledge of the subject would argue that a 0.5 threshold would make shale gas extraction unviable anywhere in the world – there’s nothing particularly different about the Bowland

        • Judith. It looks like you are saying that the shale gas industry went along with the Gold Standard assurances that they would adhere to the 0.5ML red level just to con the public, 6 years ago but had absolutely no intention of honouring that once they got their feet under the table. Hardly the actions of the caring, sharing, public spirited companies we are led to believe they are.

          • Pauline – I’m not saying that at all – I think that the people working for Cuadrilla at the time didn’t have too much expertise in seismicity. There is zero danger from fracking related tremors but thinking one can keep them under 0.5 ML is totally unrealistic

  2. As expected.

    Probably no immediate change to the traffic light but suspect as more data gathered that could happen. I suggested a while ago 1 may be the next stage, as the optimum is being established and tested.

    Time will tell.

  3. Perhaps the 3D re-evaluation by the Emiritus Prof sent to the EA has resulted in an increase in the TLS levels?

  4. John Sauven is completely correct – this was all about the movement of faults underground rather than vibration or surface effects. Caudrilla has bought itself some fake science, but I suspect that the current weak and wobbly Government is unlikely to want to be needlessly controversial right now so will stick with the science-led existing system.

    It has been interesting listening to the real science recently at the IGas Ellesmere Port planning inquiry. Government policy is self contradictory by supporting climate goals whilst also encouraging unconventional gas extraction. The planning decision is over which one takes precedence and my money is on the climate goals, which would mean the end of fracking in the U.K.

    • Maybe you could point us to the real science at Ellesmere port – from what I could see it was a mixture of poorly informed opinions and pedantic arguments that were utterly irrelevant.

  5. At the end of the day, these decisions need to be evidence based. As the evidence accumulates then that needs to be considered, and will be.

    Plenty of speculation and fabrication amongst the antis. The Governments policy will be based upon evidence.

    • ‘At the end of the day, these decisions need to be evidence based’

      What we know from 6 small fracking treatments of the Bowland shale. Source BGS.

      ‘A total of 50 seismic events in the magnitude range -2 to 2.3 ML were detected in the period 31 March to 27 May 2011’

      ‘ Earthquakes in the magnitude range 2 to 3 ML require only relatively small rupture areas, and so can occur on small faults’

      • “What we know”!!

        Not a case of what you know, John. It is what the data being collected shows and produces the evidence for competent organisations, such as BGS, to review and then provide recommendations. If you don’t agree with any outcome from such, you can challenge.

  6. “This is likely to be near the epicentre of the quake.” Sauven is such an expert that he doesnt seem to know that the epicentre of an earthquake is the point on the earth’s surface above it, not the focus, where a quake originates. Experts eh?

    • Martin – I 100% agree with you regarding the fact that Sauven has misused the word Epicentre. However, I tend to think of this as just being sloppy – a little bit like some people wrongly interchange “throw” and “displacement” when describing a fault. It would be a shame to fall into the trap of the anti-frackers wasting valuable debating time discussing irrelevancies such as whether the Pentre Chert Formation is composed of chert or shale.

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