Updated: 0.3M tremor recorded near Cuadrilla’s fracking site

The British Geological Survey recorded a small earth tremor today near Cuadrilla’s fracking site on the edge of Blackpool. This follows three micro-seismic events yesterday.

The seismic activity, the first recorded in the area since fracking began on Monday (15 October 2018), was too small to be felt at the surface.

But today’s event had a magnitude of 0.3ML, which would have put it in the amber zone of the regulations on induced seismicity had it occurred during fracking.

Under the rules, known as the traffic light system, operators are required to “proceed at caution” in amber. Fracking must stop immediately if seismic events reach 0.5ML (the red level).

The rules were introduced after fracking at Cuadrilla’s shale gas well at Preese Hall in 2011 was linked to earthquakes measuring 2.3 and 1.5.

Yesterday’s micro-seismic events measured -0.2, -0.8 and -0.3 magnitude.

All the activity was clustered on the edge of Blackpool, near the junction of A583 and Peel Road. This is the area approximately at the end of the horizontal shale gas well, called PNR1z, currently being fracked by Cuadrilla.

181018 pnr earth tremors location

Location of seismic events (yellow circles). There were two events at the most southerly point. Source: Batch Geo using maps copyright 2019 Google Imagery

181018 pnr wellbore location

Location of Cuadrilla’s shale gas well currently being fracked. Source: Cuadrilla Resources hydraulic fracturing plan

The first event was recorded at 4.48pm (BST) yesterday, followed by two others later at night at 11.54pm and 0.44am (both also BST). The depths were estimated by the BGS at 2km and 3km. Cuadrilla is fracking at a depth of about 2.2km.

Today’s event was at 2.20pm (BST) at an estimated depth of 3km.

Yesterday’s events were too small to show up on Cuadrilla’s online display of seismic data. This shows activity only in the amber and red zones of the traffic light system.

A spokesperson for Cuadrilla told us today’s 0.3ML event would also not be shown on the display. It was classed as a “trailing event” because fracking was not actually taking place:

“If we had been pumping at that time it would have indeed been an amber event we would have confirmed it.”

On yesterday’s events the spokesperson said:

“Three microseismic events were detected yesterday by the highly sensitive Traffic Light System Cuadrilla has installed around the Preston New Road site and were very far below levels that could be felt at surface. The recordings from these seismometers are shared with the British Geological Survey to help them reassure the public that operations are continuing safely as planned.

“We take the monitoring and regulation of seismicity seriously, with daily reports sent to the regulators. The microseismic events recorded were extremely low and well within the Green Light threshold and confirm that the monitoring system is working to the highest standard.”

DrillOrDrop asked the company whether it was fair to say that the events were caused by fracking. The company’s spokesperson said:

“Events of this magnitude cannot even be described as tremors. To do so implies some felt movement at surface and micro seismic measurement confirms this is simply not the case 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 microseismicty during that time. What we do know is that our detection systems are working as planned and these very low levels of seismicity are being detected.”

We also asked when the most recent hydraulic fracture treatment took place. Cuadrilla said:

“The most recent stage was completed yesterday and our hydraulic fracturing operations are continuing as planned.”

The Southampton University geologist, Dr Stephen Hicks, who has been monitoring a recent swarm of earthquakes in Surrey, tweeted:

“These are tiny “microseismic” events (not felt at the surface) and to be expected as they are probably caused by the brittle failure of small volumes of rock due to the hydraulic fracturing process. It’s good that the BGS network has such a small detection threshold.”

181019 Stephen Hicks

Dr Nick Riley, commenting on the micro-seismicity, said:

“The -0.8 event corresponds in terms of energy released to a person of average weight at 75kg jumping onto the ground from a height of 2m.”

David Smythe, emeritus professor of geophysics at University of Glasgow, who opposed Cuadrilla’s shale gas plans in Lancashire, said the events could be a warning sign:

“Recent research by Stanford University shows that these tiny tremors can be indicators of bigger quakes to follow – like canaries in a coal-mine. The problem for Cuadrilla is that if it carries on regardless, bigger earthquakes may well be triggered. To quote Cole Porter; “There may be trouble ahead”. Cuadrilla’s only safe option is to cease fracking.”

A spokesperson for the campaign group, 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.”

97 replies »

  1. I thought the idea was to break open the shale, Paula?

    What I will find more interesting over a bit of time is how manageable are the tremors. Are Cuadrilla able to turn up and down the system and control accurately what is happening under ground? Maybe they can, and maybe that’s part of the testing. Logic would indicate the objective is to achieve the maximum fracture and still not move into the red. The other area which may show up is whether when some of the horizontal is fractured will that absorb some of the energy from neighbouring sections and muffle any tremors? No idea myself, but I expect there are some oilies who may know that.

    • Gentle on the lever now. Slowly does it. Ignore the repeat calls from investors to pull harder.

      A reminder of what the BGS stated in their report with reference to Cuadrilla’s request for a 1.7 magnitude threshold,

      ‘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 0.9ML. 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’

      Cuadrilla may need the 2.6 magnitude threshold to get at the gas and keep hold of the investors

      The poor flow test results from Preese Hall came from information obtained from fracking which triggered a 2.3 magnitude earthquake. That was the world’s second largest earthquake ever recorded from fracking in shale.

      Little frack, nothing back.

      Each 1 magnitude rise is 10 times stronger than the previous level.

      To the guy on the lever

      Remember what the BGS have told you…………..

      “earthquakes in the magnitude range 2 to 3 ML require only relatively small rupture areas, and so can occur on small faults”


      “There is no evidence to suggest that the causative fault is unique and knowledge of faulting in the basin is poor, so it is quite possible that there are many such faults throughout the basin. A critical state of stress is widely expected at depth and observed throughout the Earth’s crust”

      No pressure then……..Or is there?

  2. Help me out then Paula.

    I have never conducted any fracking myself so am interested to know some of the technicalities. Not that interested in uninformed speculation but if you are able to supply some factual information I would be interested.

    Maybe Cole Porter can help us out some more?

    “What’s this awful hullabaloo?”

  3. Puala. Unlike many amti frackers like yourself who are not qualified to make technical or expertise decision in the real world but yet determine to impose their unqualified opinuons on others Martin at least being honest about his remarks.

  4. In my layman view, this is both a blessing and a curse for Cuadrilla. It may mean that the fraccing is working in cracking the shale and shale is very brittle and easy to frack and crack which means the network of existing natural fracture and new one will be connected extensively amd make it easier for gas flow. But also means they have to go slow and watch out for these seismic events more carefully.

  5. Maybe the option Cuadrilla take is to let the fractured shale settled over the weekend before continuing with next step. Use more sand to hold the crack in place and less fluid and lubricant.

  6. This makes me laugh .. fracking is opening up fractures in the target area of course there will be minor seismic events [edited by moderator]

  7. Don’t forget folks that this ‘test’ to see if there is an commercial supply of gas, one which should normally take 2 weeks. This unmentionable company is going to take 3 months! They are so desperate not to mess it up. As we all know which company messed it up last time. Perhaps they are on a very, very, very slow course to doing the same again. By the way the above mentioned time-scales I believe are those provided by one Franny (I don’t live in Lancashire) Egan. You reap what you sow.

    • The anticipation is like the steep climb to the top of the ‘Big One’……it shakes and rattles causing nervous gasps until……………………………………over the top, no going back! Then it’ll be Jerry Lee Lewis

      Come along my baby, whole lotta shakin’ goin’ on
      Yes, I said come along my baby, baby you can’t go wrong
      We ain’t fakin’, while lotta shakin’ goin’ on

      Well, I said come along my baby, we got shale gas in the ground
      Woo-huh, come along my baby, really got the bullshit by the mound
      We ain’t fakin’, whole lotta shakin’ goin’ on

      Well, I said shake, baby, shake
      I said shake, baby, shake
      I said shake it, baby, shake it
      And then shake, baby, shake
      Come on over, whole lotta shakin’ goin’ on
      Oh, let’s go!


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