Earthquake monitors installed in Surrey – welcomed by campaigners

180711Installing seismic monitors BGS

First seismic monitor installed in Surrey on 11 July 2018. Photo: Used with the owner’s permission

The British Geological Survey has installed two seismic monitors in Surrey to track earthquakes following a recent cluster centred near Newdigate.

The installation was welcomed by two campaign groups and the Green Party MEP for the region, Keith Taylor. They have called for an investigation into any links between the earthquakes and local oil and gas operations.

The most recent earthquake in the cluster was on Tuesday (10 July 2018). This is the eighth in the same area in about three months. The first was on 1 April 2018 and the largest so far, on 5 July 2018, had a magnitude of 3.1.

The BGS said the latest earthquake was recorded at just after 4pm and felt by a few people living in Newdigate and Charlwood in Surrey. They described it as:

“felt a thud and a very slight vibration through chair”

“slight impact followed by two or three seconds shaking, but much less obvious than previous ones”.

Of the past 10 UK earthquakes, four have centred on Newdigate. Before that, the county had no reported earthquakes for 50 years.

180712 seismic chart

The BGS said of the new monitors:

“We hope to gain a better understanding of this scientific phenomena through the installation of additional stations.”

180713 earthquake map rush and airport

The first monitoring station, called Rush (white triangle), and the locations of recent earthquakes (red circles). Map base: Google Earth

The first monitor, installed yesterday (11 July 2018), is at Russ Hill.

Seismologist Dr Stephen Hicks, who was part of the installation team, said this was directly above the current best estimate for the epicentres. He said a second station had been installed in the Norwood Hill/Horley area.

Before the new monitors were installed, the nearest seismic station in the BGS network was on the East Sussex coast, about 50km away.

Dr Hicks, a postdoctoral research fellow in passive source seismology at Southampton University, said:

“The lack of close seismic stations means that we were unable to pinpoint the exact epicentre of the earthquakes. The locations had uncertainties of several kilometres and it was even harder to determine the depth at which they occurred.”

He said the depth of the earthquake, quoted as 5km, could actually be shallower or deeper. The new monitors would provide the best coverage of the seismic events:

“They will give us a good chance to determine accurate locations. The new stations will also tell us if smaller, previously unreported earthquakes are occurring in the swarm which are not being felt by people on the ground.”

Dr Hicks said the monitors would be in place for at least a few months, perhaps up to a year. If the data quality was good enough, they could become permanent, he said.

Data from both stations was now being sent to the BGS centre in Edinburgh, Dr Hicks said, and should be publicly available at some point on the BGS website.


180712 installing seismic monitors

Second seismic monitor installed in Surrey today (12 July 2018). Photo: Used with the owner’s permission

The earthquakes have prompted calls for an investigation into any link with the county’s oil and gas industry. There are two oil sites within about 10km of the apparent epicentre: Horse Hill, near Gatwick, and Brockham, near Dorking.

Dr Hicks, who lives in Surrey, said

“In my opinion, based on past seismicity around the UK, the most likely scenario is that this earthquake sequence is natural and will die off in the future. But, we certainly cannot rule out future earthquakes. We have no way to predict when and where earthquakes are going to occur.

“Based on our knowledge about the type of hydrocarbon activities (e.g. Horse Hill and Brockham wells) in the area, and scientific studies of human-induced earthquakes around the world, there is no clear evidence at present to suggest that there is a directly link with the Surrey earthquakes.

“If earthquakes continue to occur, then thorough scientific analysis of seismic and geological data, combined with operational data from any industrial activities in the vicinity, will be needed to rule in or rule out any causative link.

“If the earthquakes continue in Surrey, data the new seismic stations will prove vital for further operational monitoring and future scientific studies about the different causes of earthquakes in and around the UK.”


BGS map showing estimated epicentres of the earthquakes (yellow stars), PEDL areas (purple squares) and well sites (small blue squares)

James Hill, a member of the campaign group, A Voice for Leith Hill, said:

“Gathering local data is really important. We don’t know yet what started this period of seismic activity, but we know that the permits for the Surrey well sites were all approved before it was understood to be active for earthquakes.

“More worrying still is the possibility that a seismically stable region may have been turned into an active earthquake zone by some of the processes used by the oil and gas companies.

“Intensive techniques used to stimulate the flow of oil or gas from shale rock are under scrutiny here, as is the re-injection of contaminated waste water. Our geology is heavily faulted yet there are no rules to prevent drilling near these faults.”

“Whatever the cause, the regulators of drilling – the Oil and Gas Authority, the Health and Safety Executive and the Environment Agency – should suspend the licences to operate until it is certain that activities at these sites are safe. It is extremely risky to be carrying out any deep underground activities in an area where the geology is unstable.”

Another group, Brockham Oil Watch, said:

“No further planning permissions should be granted for exploration, appraisal or production from hydrocarbon development sites until the current swarm of earthquakes has been fully investigated and a protocol developed to minimise the risk of significant environmental harm from hydrocarbon development activities.

“All existing hydrocarbon development planning applications should be placed on hold until this protocol has been developed to an acceptable level of detail.”

The Green Party MEP for south east England, Keith Taylor, said:

“The seismic activity in an area where unconventional fossil fuel drilling and testing is active is clearly extremely concerning. It is also unprecedented in the Weald in the last half a century. At the same time, the links between earthquakes and the unconventional onshore oil and gas drilling industry are well established.”

“I welcome the British Geological Survey’s efforts here to further monitor this activity and would add that it is only sensible to put a moratorium on any oil and gas activity in the geological region until the results of the investigation are clear. The case for employing the precautionary principle couldn’t be any clearer.”

34 replies »

    • Perhaps they won’t be welcomed by “respected geologist” Stephen Sanderson, who has stated it can’t be UKOG, the earthquakes are at 5000m depth and that their flow testing in 2016 including acidisation was done at shallower depths. But why are all 8 earthquakes at 5000m EXACTLY?
      That’s because the monitoring stations were all over 50 kms away so it’s just impossible to measure the timy fractions of a degree down from ground level at that distance, so the BGS enter a nominal value, 5000m.
      These new monitoring stations, which we have been calling for, will be particularly well placed to measure depth, so keep an eye out and see who is right, me or Steve?
      Squeeky bum time for UKOG investors!

      • So I checked SS’s press statement, he actually said

        “We would also like to point out that there was no recorded seismicity associated with our 2014 drilling and 2016 flow testing, nor are we aware that any of the other 80-plus wells drilled or flowed in the Weald are associated with any seismicity. Furthermore, as the BGS have stated, the source of this seismicity is related to a deep-seated basement fault at around 5.5 km below surface, 4.5 km deeper than our activities at Horse Hill.”

        Apologies to Mr Sanderson, I remembered he had said 5000m, which is the value the nominal BGS put for the earthquakes, but he said 5500m for some reason.

        The point remains that the actual epicentres could be shallower or slightly deeper than the BGS nominal value of 5000m. The lesson from Preese Hall was that the subsurface activity (fracking in that case) was at a different depth and location to the epicentre anyway so my point is that it’s misleading.

        It also misleading to say there has been “no recorded seismicity associated with our 2014 drilling and 2016 flow testing” this could be it. The studies in the states show there can be delayed effects, so it is possible that previous sub surface events were the trigger for this cluster, we can’t know at this stage so let’s not pre judge it.

        The BGS call this a scientific phenomenon and are unable to say yet if it’s cause is man made or natural, we shouldn’t decide based on our prejudices, but we do need an answer. That’s why there needs to be proper 3D surveying of the faults and a proper study carried out, you cannot decide that it is safe to continue with out understanding the faulting.

        Let’s see what our Gold Standard Regulators come up with.

    • Sherwulfe
      Looking at the Ollerton Earthquakes 2013, or the Edwinstowe Earthquakes 1998-1990 they install additional monitoring to fine tune their data.

  1. Caused by oil and gas operations or not, I think there will be ongoing concern for homeowners, insurance companies and Gatwick Airport if swarm continues or if magnitude increases, plus pipeline integrity will be at risk

  2. Increased seismic activity due to Fracking could result in increased possibility of contamination of groundwater. We should be looking after our water not poisoning it !

  3. Sanderson’s well documented back to back wells across the Weald statement means that the chances are increased of damage to well casings similar to the 2.3 Quake in Blackpool where Cuadrilla took 6 Months to report that there was a problem . That well has been abandoned and who knows what could be leaking from it. Waste reinjection has been happening at Brockham for years including that transported from Lidsey this waste could over a period of time reach a fault that is under pressure causing it to move . Reinjection is the main cause of earthquakes associated with oil and gas extraction in the USA.

    • “Reinjection is the main cause of earthquakes associated with oil and gas extraction in the USA.” . That is not correct. It is the disposal of waste water which has caused the issues in the US. They pump huge volumes of waste of all kinds, oil waste, chemical waste, industrial waste, at very high rates down dedicated disposal wells over periods of decades. Reinjection in this case is the replacement of the water extracted from the same single well or field. It bears very little resemblance to anything in the US. It is still possible to change the pressure environment of the reservoir with reinjection, the aim is to maintain pressure from a producing well after all, but to compare the reinjection of produced water from a tiny onshore UK well to the process in the US is plain wrong,

      • Martin Decker, reinjection at Brockham includes not only water produced at Brockham, but also at Lidsey. The reinjection well has been there since 2007, and so reinjection took place over a number of years. Experts commenting on the recent quakes say that a link cannot be ruled out at this stage as much depends on the local geology. Also, there is no reinjection data available to conduct even the most rudimentary analysis. The last available reinjection data for Brockham is from March this year! It is only a monthly average and not verified in any way.

    • Jono
      See the report well aired in DOD re the investigation into those Blackpool Quakes.
      The well casing was slightly deformed, but integrity was maintained.

      So we know it not leaking, as do the operators.

      Look up deformed casing in google to understand the issue.

      • Also possible that the notorious “deformed” casing red herring was caused by hydraulic pressure during the stimulation when pump pressure was bled off (if collapse rating exceeded by trapped annulus pressure, or weak joint / poor cement at that point / above packer with no annulus pressure above packer etc. etc.).

        • It was partially flattened into an oval shape, does that fit your your hypothesis? Do a lot of wells get abandoned due to “red herrings”?

          • Not that uncommon for the reasons stated above. Often they are side tracked above the “red herring” if the objective has not been drilled. Also if the well is to be completed as a production well and internal tools need to pass through the restriction / or the casing pressure test has failed. If the well is to be perforated below the restriction and the packer above the restriction and guns can pass through then there is no reason not to complete the well. Oval shape is usually what happens if it is pressure related as casing is manufactured to a +/- 12-1/2″% wall thickness so the casing may be weaker in one plane therefore resulting in ovality in the presence of excess hydraulic pressure.

            • Thank goodness we have experienced “experts” such as yourself Sherwulfe contributing to this BB….

            • At no point, Paul, unlike some, do I pretend to be a drilling expert; you yourself have flagged up the weakness, my comment was just pointing out the reaction to using sub-standard equipment that you yourself have confirmed.

            • Sherwulfe – sub standard equipment – please explain – from a technical standpoint rather than wishful thinking? Where did I say equipment was sub standard?

            • Do you not read what you have written?
              ‘so the casing may be weaker in one plane therefore resulting in ovality’

            • Not sub-standard – manufactured to specification i.e. the standards. +/- 12-1/2%WT is the specification. You could look the standards up? The error if there was one is in the pressure exceeding the design collapse (or burst) pressure which incorporates the margin on WT.

            • You are clearly not an engineer. Even your wind turbine and PV panels will be constructed from materials made to a specifc specification. But not to worry, we will all know fairly soon if this onshore shale gas (the Bowland Shale) is viable or not. Based on the flow rates estimated at Preese Hall and the persistence of Cuadrilla, INEOS, BGS, Centrica, OGA etc. there is a reasonable chance that it will be.

            • ah, but this ‘specification’ does not result in a weakness; twenty years on and never missed a beat…..

            • Hmmmm
              Turbine blades fail in service and some fall over in Germany.
              Turbine generators also fail in service ( as a relative of mine is glad to note as it’s good business to fix them).
              Over speed regulator devices have also failed.
              Cardboard standards maybe. But many are ok.

              Meanwhile hundreds of onshore wells are ok ( not oval ).
              Maybe it’s just a wind up conversation.

            • Dorkinian, thanks for the link which contains the following comments:

              “A spokesperson for the Health and Safety Executive told VICE News: “Some may interpret increased pressure in the annulus as a well integrity issue. The pressure increase in the annulus was well within the design parameters and does not constitute a risk to the health and safety of people; therefore it was not reportable to HSE.

              “There was no leak of fluids from the well and the issue has been resolved during the abandonment process. HSE inspectors will continue to monitor the situation.””

              I wouldn’t worry too much about what Caroline Lucas or Mike Hill or Anthony Ingraffea think – they all have another agenda.

              “John Bissett, the discipline leader in well construction at Robert Gordon University, said: “It is quite clear that well integrity has been breached, technically. How significant that failure is could be a matter for discussion.” He added that the failure is “potentially significant for any planned future wells and fracturing activities.””

              John Bissett does think there was a “technical breach” whatever that means. A quick search of RGU does not come up with a John Bissett so perhaps he has left. But in the RGU capacity noted he is certainly qualified to comment.

              It would be interesting to read the series of e-mails – Ruth / Paul is this possible?

  4. Oh, now we have a “statement” likely to increase incidence of earthquakes!!

    Let’s all try it. I hereby issue a statement that I will win the lottery this weekend. Wish me luck.

    (I think you will find they are still trying to get significant oil out of one well. Back to back wells are conjecture, whoever makes the statement.)

  5. Around PNR, Lancashire they have 10 monitors but they can not tell you much as they are all near roads. So far they have only shown how much traffic has increased in the area.
    Any small tremors are scribbled out by the amount of vehicle movement.
    Earthquakes do show up but you can not tell how big they are when they hit.
    Just a thought when you have to keep a watch in your area.
    BGS monitors do not give the public much information.

    • Thanks Netty, these are well set back from the road, and the setting is more rural as well. So hopefully less background noise.

  6. 18/7/18 Another earthquake recorded today in Newdigate. The 9th this year but the first with the new monitoring equipment.
    Depth of between 300 and 700 metres.

    Any comments?

  7. Apologies, there have actually there have been 2 sepearate earthquakes today 18/7/18. So that now makes 10 felt qaukes this year.

    Strange how the seismic activity has suddenly started up after being dormant for generations. Is it sheer coincidence that it has occurred in the same place, period and depth as the works being carried out at Horse Hill and Brockham?

    It could, of course, just be sheer bad luck for UKOG, Angus, etc

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