Research

Surrey earthquakes: no link to oil and gas sites, says report, but one expert disagrees

HazeldineHHPres1Map

Newdigate Earthquake swarm. Source: Haszeldine & Cavanagh, OGA Workshop, October 2018

A report on the swarm of earthquakes in Surrey earlier this year finds no evidence they were triggered by oil and gas operations. But an academic who contributed to the official investigation into the cause of the quakes disagrees with the conclusion and critics of onshore drilling have described the findings as a “whitewash”.

The earthquakes happened mostly between 1 April and 18 July in the area around Newdigate near Gatwick. The nearest oil and gas sites to the earthquake epicentres were Horse Hill, near Horley, and Brockham, near Dorking. The operators of both sites denied any connection between their activities and the seismic events.

The likely cause of the earthquakes was discussed at a workshop of more than 20 academics and regulators last month. The report, published today by the government’s Oil & Gas Authority, stated:

“Participants concluded that based on the evidence presented, there was no causal link between the seismic events and oil and gas activity.”

But Stuart Haszeldine, Professor of Carbon Capture and Storage at Edinburgh University, who took part in the workshop, told DrillOrDrop tonight that the earthquakes passed almost all the tests used to decide whether they were induced by human activity.

The workshop discussions centred on the tests, known as the Davis & Frohlich Criteria, developed in the United States. They ask six questions, which if answered yes, suggest the earthquakes were likely to be induced, rather than natural. Most of the participants said the Newdigate earthquakes passed only one of the tests but Professor Haszeldine said they passed five and possibly all six.

180705 BGSNewdigate

Earthquake near Newdigate 5 July 2018 Source: British Geological Survey

Earthquake criteria

Are the earthquakes unusual?

The Davis & Frohlich Criteria ask whether the earthquakes were exceptional in the region. The majority of participants pointed to three small earthquakes in Billingshurst, about 20km away, in 2005, as evidence that there had been earthquakes in the Weald basin.

Professor Haszeldine said in his presentation that the 14 Newdigate earthquakes in a three-month period were without precedent in the Weald Basin. He said there had been only eight shallow earthquakes in the entire regional area in the previous 40 years. He said the Billingshurst earthquakes were at a depth of 5km, much deeper than the Newdigate series, most of which were at an estimated depth of 1.5-2km.

Did the events happen around the same time as oil and gas activity?

Richard Luckett, of the British Geological Survey, another workshop participant, said there was a link between the earthquakes and local oil and gas operations. He said production work had started at the Brockham oil field, near Dorking, on 29 March, three days before the first earthquake on 1 April.

The operator of the Horse Hill well provided evidence to the workshop that there was no activity at Horse Hill between March 2016 and 25 June 2018. It said flow testing did not start until July 2018, long after the start of the earthquake series. DrillOrDrop previously reported statements by the company that it was not to blame (here and here).

But Professor Haszeldine described the timeline of activity at Horse Hill as “compelling”.

Groundwork began at Horse Hill on 12 March 2018, before the earthquake sequence began. A new cellar was excavated, starting on 21 March. Campaigners have provided evidence that there were staff onsite on the Horse Hill site on 1 April 2018, the day of the first earthquake. Well integrity tests were carried out on 5-6 April 2018 by checking annular pressure.

Professor Haszeline’s timeline showed that the deployment of a perforation gun on 13-17 August was followed by a seismic event on 18 August.

180712 installing seismic monitors

Temporary seismic monitoring installed in Surrey. Photo: British Geological Survey

Are the epicentres within 5km of oil and gas wells?

Richard Luckett, of the BGS, answered ‘no’ to this question. He argued in his presentation that seismicity can be induced at distances of 10km or more – but only where there is large volumes of injected liquid. He said the Brockham well, at 8km from the epicentres, was too far away to meet this test because the volume of liquid was very small .

But Professor Haszeldine said the Horse Hill site met this test. The cluster of earthquakes and a magnitude 3 event were only 3km away from Horse Hill, he said.

Were the seismic events at or near exploration target depths?

Workshop participants had argued that the Newdigate earthquakes probably did not meet this condition. The workshop heard that production at the Brockham site was at a depth of about 600m, while the earthquakes were at about 2.1km.

But Professor Haszeldine said the Portland and Kimmeridge targets of the Horse Hill well were at the same depths of some of the seismic events.

Do geological structures connect the earthquakes to oil and gas operations?

Richard Luckett answered ‘probably no’ to this question. But Professor Haszeldine said a normal fault passes NE-SW through the cluster and the Horse Hill well. He also said there had been different interpretations of the epicentre of the earthquakes and that individual interpretations had changed.

Are subsurface changes in fluid pressure sufficient to cause seismicity?

Workshop participants answered ‘probably no’ to this question. Angus Energy had restarted producing oil at Brockham just before the first earthquake, after a two-year break. Produced water was being reinjected into the Portland sandstone reservoir. But at the time of the first earthquake, 3m3 would have been injected, the workshope heard. This compared with approximately 100m3-1,000m3/day at other sites which are known to have induced seismicity.

Professor Haszeldine answered ‘maybe’ to this question. He proposed a hypothesis of how the Horse Hill well could be linked to the earthquakes through fluid pressure changes.

According to his hypothesis, gas pressure built up in the well during the time it was shut in between 2016-2018. Gas moved up between the cement and the formation, because of a less than perfect cement bond. In late March 2018, as part of preparations to work on the well, the pressure was released at the surface. The sudden reduction in pressure below ground caused the fault to slip, triggering the earthquakes.

More research

The Oil & Gas Authority report called for a UK-specific scheme for assessing the likelihood of induced seismicity. Professor Haszeline said he was working with colleagues at Edinburgh on an academic paper on this subject, based on the Newdigate earthquakes. He also said:

“There needs to be a record of activity on oil and gas sites. We need evidence of all the activity on the surface which should be verified and archived at the time so that it can be gone back to in the future.”

The report also said

“There was a general desire for additional seismometers to be added to the BGS national network but it was agreed that the current government funding for micro-seismic baseline monitoring is appropriately limited to areas where hydraulic fracturing is proposed.”

Professor Haszeldine said additional seismometers could be installed at oil and gas sites for about £10,000.

Reaction

James Knapp of the Weald Action Group said;

“The Newdigate Swarm of earthquakes have been located to a small fault running NE from the cluster to Horse Hill exploratory oil well, just 3 kms away, which is bored straight through it.

“It speaks volumes that the only way to reach the finding that the earthquake swarm is natural, is to disregard the existence of the Horse Hill well site altogether, and this is exactly what has been done for this report.

“A fully independent investigation by Edinburgh University came to the opposite conclusion, that the earthquakes were induced by exploration activity, and they have produced a hypothesis which shows how Horse Hill well could have triggered the earthquakes.

“The OGA report obscures the danger of the planned expansion at Horse Hill, from a single exploration well to seven production and injection wells. It also highlights the contradiction at the heart of oil and gas regulation: How can the Oil and Gas Authority, whose job it is to maximise oil and gas production, simultaneously offer the required checks and balances of a regulator? This flawed regulatory structure undermines public trust in the Government’s energy policy at a time when the IPCC tell us we have just 12 years to stop run away climate change.

“Just like the troubled fracking at Preston New Road and the abandoned Preese Hall well, these tremors are happening because we don’t have a legally imposed respect distance for drilling near faults. This is most relevant to the deviated and horizontal wells needed for tight oil and gas production, to mitigate risk both of inducing earthquakes and of water pollution.

“This blinkered report manages to avoid conflict with the government’s policy for a new era of damaging onshore fossil fuel extraction, and can best be described as a whitewash.”

Keith Taylor, MEP for South East England said:

“The OGA’s findings do not represent a scientific consensus. Some independent experts have assessed the same available data and reached a very different conclusion; finding that human activity was likely to be linked to the unprecedented seismic activity in Surrey. The OGA exists to promote and facilitate oil and gas drilling; their conclusion, and certainty with which they present it, may be disappointing but it is hardly surprising.

“Oil and gas firms are desperate to continue their climate-destructive operations unimpeded by concerns over their seismic impact. But, however much the oil and gas industry may wish to sweep them away, questions about the links between the Surrey earthquake swarm and oil and gas drilling in the region still loom large.

“While those questions remain unanswered, I will continue to support experts’ calls for a moratorium on all oil and gas drilling in the area.

“The case for employing the precautionary principle is obvious. That we have witnessed unprecedented seismic activity in an area where unconventional fossil fuel drilling sites are active is, clearly, extremely concerning. Until the experts are able to form a consensus on the possible cause, a moratorium remains the most sensible course of action for all involved.”

71 replies »

  1. I recall GBK, that the plan was for China to fund 400 coal fired stations outside of China. Puts our efforts into some context.

    Also interested to see the cost and scale of the N.Sea field outlined today-Clair. £4.9 billion, 120k barrels/day at peak.

    Output pretty similar to peak output from Wytch Farm. Cost somewhat different!

  2. Well David the experts have formed a consensus on what the cause wasn’t, so not an issue.

    Has there been any where near a consensus regarding the cause of hundreds of other seismic events every year across the UK? Yep-they are natural random events. Operate a precautionary principle around all of those? Hardly.

  3. This is the long delayed and widely expected OGA cover up. First they get the BGS to do a limited study (they are after all funded partly by government, partly by the oil industry directly), then they feed them the story that UKOG wanted them to hear (no activity on site until after the earthquakes started). Then they fill the room with OGA, regulators and industry reps, plus a few on side academics. But the signatories of the letter to the Secretary of State asking for a moratorium (and who recommended measures be imposed to stop drilling through faults) were also invited and some credit is due for that.

    Have any of you AIM investors understood the linked report from Edinburgh University? Or even read it? It is a scientific hypothesis YET TO BE DISPROVEN and the only independent investigation into what triggered the Newdigate Swarm. The OGA argument is that an Act of God started the earthquakes three days after plinth reconstruction work started at Horse Hill, and another Act of God stopped the earthquakes after the test production started.

    And now two injection wells are planned for Horse Hill, wonder how that will go? Yee-ha!

    It seems nothing has been learnt from the failures at Preese Hall and PNR.

    • Gosh – the anti-frackers do like their conspiracy theories don’t you? Are you going to tell us about chemtrails next?

      • Dorkian

        The presentation by Prof Hazeldine is interesting.

        I do note that the presentation had taken the Davis and Frohlich questions, which are aimed at injection wells, and applied them to other activities not related to injection and a well that is not an injection well HH1

        The 1993 Davis and Frohlich paper is linked below

        https://scits.stanford.edu/sites/default/files/207.full_.pdf

        Their 6 questions relate to injection activities, so you need to think of that when answering them.

        Differences are ( Hazeldine presentation first, D&F second.)

        1. Are these earthquakes exceptional to the region?

        Are these events the first known events of this character in the region?

        So, are the events the first known in the Regions? D&F note that the the questions are subjective, so some flexibilty is required.

        How far should we go back to determine if they are the first known events of this character in the region ever?
        Presumably we should field all relevant records to determine that.

        The presentation goes back to the 1980s, BGS data goes back further to less defined the further back one goes.

        In the BGS report of 2018 ( link below ) there is a more extensive discussion of region earthquake activity that the presentation. The BGS conclude that the earthquakes are not unprecedented to the region.

        http://earthquakes.bgs.ac.uk/research/NewdigateEarthquakesReport.pdf

        Why we have moved from ‘first known in the region’ to exceptional for Hazeldine or unprecedented for the BGS is interesting, but the BGS do use the D&F questions verbatim in their report.

        2. Is there a correlation with HH 1 operations?

        Is there a clear correlation between injection and seismicity?

        HH 1 is not an injection well, so linking various activities such as excavating a hole in the ground and other well test activities do not seem relevant to the question, which is, is there a correlation between objectivity and seismicity.

        The BGS discuss Brockham ( an injection well ) and HH1, which is not and conclude a no.

        3. Are the earthquakes close (5km) to HH well location?

        3a Are epicentres near wells (5km)? ( note that D&F have Q 3a to 3c )

        As HH is not an injector, then the answer would be no on the basis of that alone?

        BGS look at injection at Brockham as well as HH, noting that Brockham is 8km away, that some studies show large volumes of injection may cause earthquakes 20km away. Then you note the small volumes of re injection at Brockham.

        4 to 6

        Hazeldine refers to HH for 4 and 5 without noting that the questions relate to injection wells.

        In 6 he proposes an interesting way seismic activity could occur.

        Overall, it seems that BGS and the good prof are not singing from the same hymn sheet, and one could guess that may be why the BGS and the good Prof reach different conclusions when using the D&F question set for injection wells.

        Maybe links or evidence showing the link between normal drilling and flow testing to seismic activity would be good ( of a scale similar to the Weald I would add to save getting links to newspaper articles re Groningen ). Or more info on annulus depressurising causing earthquakes ( unless this is a global first ) would be good.

        [edit at poster’s request]

          • There is of course a much simpler test; one you don’t need any first degrees, higher degrees, three degrees or other artists formally known as experts….

            Were there any earthquakes in the region before operations commenced? If not, conclusion – induced. If yes, what was their frequency?Did frequency increase exponentially? Answer yes – induced.

            [Typo corrected at poster’s request]

            • Sherwulfe
              That is one way of looking at it.

              The other is that we’re there any earthquakes in the region when Operations commenced many years ago.

              A timeline of past oil and gas activity and seismic activity is required to see if there is correlation between activity and events. Just looking for activity when you have a seismic event is not the same.

              Hence the D&F question set.

              Meanwhile I will look to see how the Kent Coalmines fared re Seismic Tremors. Three pits, lots of subsidence, holes in the ground, shotfiring and so on and in the area.

            • Sherwulfe – what a brilliant explanation. I realise now what a bad girl my daughter is – she flew to Nepal and the next day 10,000 died from an earthquake there. Note to self – don’t fly to same countries as my daughter because she causes earthquakes.

            • Obviously hewes. all potential possibilities must be investigated; but when looking into the causal effect of a seismic event on a timeline the most obvious is often overlooked. There are too many who want to find an alternative explanation even though the answer is right in front of them; it does not fit in their belief system you see – challenge that and you just get comments like Judith’s strange one about her daughter and Nepal. The human spirit does not like it’s belief system challenged and the resulting anxiety looks for another, always less credible but fiercely defended, explanation. It’s a shame, for if we could act on what is right in front of us, the human race would be in a much better place [climate change escalation for one example].

        • Hewes62 – I hadn’t realised that his presentation was on-line. Having read through it, I’m shocked just how delusional Prof Haszeldine’s hypothesis is for fault reactivation as well as his shear ignorance of PVTbehavior for methane. Addressing the first point, normally depressurisation would increase the normal stress on the fault in comparison to the shear stress leading to increased fault stability. This is not always they case as it depends on something called the horizontal stress path coefficient, which links pore pressure to total stress. However, it would be rather odd for stress path coefficients in rocks such as these to be such that fault reactivation would occur – the opposite would occur. Secondly, the picture on his slide shows someone demonstrating the flow of gas during depressurisation. I can assure you of one thing, if the well annulus has been connected to a sufficient volume of high pressure gas needed to affect local stresses then the guy would not have been holding the hose pipe! The presentation by Prof Haszeldine simply shows his poor crasp of geomechanics and petroleum engineering. I’m not the first to point this out, Mark Zoback from Stanford has written several papers pointing out how CCS could lead to earthquakes whereas fracking for shale will in the long-term have to opposite effect. Haszeldine clearly hasn’t grasped these basics.

          • Judith

            I thought that Paul Tresco May have a view on the leak path hypothesis and then the venting bit.

            The photograph in the presentation says Balcombe, so… not the well discussed, and, as you note, given the amount of gas to bleed that the hypothesis requires, the annulus would be connected to the flare.

            There is also an assumption that the annulus is not bled during shut in, and that it is bled to atmospheric pressure post shut in, but no confirmation this is the case.

            Those interested may play … spot the difference … in what is shown as annulus bleeding at balcombe and what you would see at WYF or HH1 say ( or any Bp or Shell well ).

            • Hewes 62 – not sure what you want me to comment on regarding gas / annulus / leak path? Please advise?

            • Paul

              I wondered if you had any thoughts on the annulus bleeding components of the professors hypothesis linked to the 6th Question as described in the presentation slides, in particular slides 13 to 30.

            • Hewes62 – it would also be interesting to know more about the pressure readings on slide 29. For example, what depths were they taken and whether he’s trying to argue depressurisation from 80 psi was responsible for the tremors. Also. Is he really arguing that a pressure wave from a perforation gun travelled 2,5 km and caused an earthquake?

            • Thanks Hewes62 – difficult to understand what he is trying to say here. Which annulus is he talking about? Where were the pressure readings taken? Is it the production annulus which exhibited pressure which was bled off? If so this blows the whole theory. Is it the production casing to intermediate or surface casing annulus? Did they drill into an over pressured gas zone at TD of the well? Presumably weighted up, killed the well. Then ran and cemented casing on top of overpressure zone at TD? The additional mud weight will already have impacted on zone 2. No eathquake? Next he assumes the annulus cement is channeled to surface? Very unlikely but if so should have been seen during cement placement and / or bond logging? Then the over pressure zone flows into the shallower zone 2 and also displaces the fluid in the annulus channel so gas at surface with a pressure of 80psi? This is in effect an underground blow out with an annulus wellhead pressure equivalent to the bottom hole flowing pressure at zone 2 less a hydrostatic head of gas. Then this annulus pressure is bled down to zero through a small hose at surface? This doesn’t make sense. Gas should be flowing at a significant rate from the annulus and as you / Judith have alluded to, would require at least to be flowed through a choke and vented / flared. And it would be unlikely to bleed down unless it bridged off. Or the volume was very small and finite. Either way no earthquake. The 80 psi is more likely due to thermal expansion particularly if there is not good cement at surface. The fact that the technician in the photos is straddling the hose indicates he is not overly concerned about a lot of gas and fluid flowing up the well annulus from an over pressured zone at TD. Unless he wanted a cheap vasectomy?

              Seems very far fetched – and if you look at volumes (of liquids, not gas) required to frack wells and induce seismicity this theory looks even more unlikely.

            • Paul – thanks for the insight. Interesting, that all the experts on fracking and:or well completions on this page haven’t questioned your views. Surely it couldn’t be the case that your analysis is correct and their understanding is close to zero could it? 😂😂

  4. The title is this article is totally misleading – the person named who thinks that the tremors were caused by petroleum extraction has no expertise in seismology. He is not an expert

  5. So, a group of over 20 academics actually had one who disagreed with all the rest!

    Shock/horror.

    Absolutely normal. Find any such group where that is not the case.

    But, Mr. Taylor, that is what a consensus is.

    No story here, just a few trying to make out reality is not the real world. Too much RT.

  6. Hello Hewes,

    Refreshing that you do actually look at the data unlike some other posters who go straight to the ad hominem attacks or attempt to change the subject and discuss China.

    You are right that the Davis Frohlich test is focused on disposal wells, i.e. waste water injected into porous rock strata. There are other possible industrial causes of earthquakes though (for instance the Preese Hall and PNR tremors weren’t caused by disposal wells) but it was the most relevant test available so it has been adopted and is being used here on wells generally, not just disposal wells. To be clear, the reason the BGS say they disregarded Horse Hill’s HH-1 well was not because it isn’t an injection well, it is because there was no one on site at the time.

    A well that was “shut-in” according to the operators is still an existing well so a simple question like Are the epicentres near wells (within 5 kms)? should be answered “Yes” because the distance is 3 kms (along the connecting fault to HH-1) and if Horse Hill well had been considered a full investigation into the possible connection between the well and the tremors would follow.

    Just 2 or 3 “yes” answers would be enough to indicate induced seismicity according to the BGS. In case you are wondering, I went to Dr Richard Luckett’s talk at Newdigate on Oct 3rd. and recorded the whole presentation which was similar to the talk he gave to the OGA workshop earlier that day.

    But in any case the BGS and regulators were shown evidence that there WAS work at HH in late March, They were sent drone pictures that were taken on April 1st. showing the civil works, activities which fit with the Edinburgh hypothesis.

    Re. local seismicity, yes the 1551 earthquake was felt at Dorking but this cannot reasonably convince that there are historical earthquakes of the same character. We have no location or depth to compare or evidence that the quake was even felt at Newdigate let alone centred anywhere near there.

    The only real contenders for historical earthquakes “of the same character” are the three Billingshurst earthquakes. Here, the differences in character are obvious- the BGS given depths are in the ‘basement’, the hard crystalline bedrock where you would expect them to be, not the shallower sedimentary layers (shallow earthquakes are a marker for induced seismicity) and they cannot be on the same 4 km long fault as they are 20-25 kms away.

    Applying the word “region” from the Davis Frohlich test requires some honesty and common sense. Is the “region” SE England, the entire Weald or is it only truly relevant to read it as meaning the actual region of the of tremors, which in this case are clustered along the Newdigate fault? The BGS very generously say anywhere in the entire Weald counts as the “region”. But still the significance of the difference in depths i.e. sedimentary layers v. bedrock mean the “characters” do not match, and they cannot be from the same fault.

    It will be interesting to see if a legal challenge emerges.

      • Do I happen to have? Is that you patronising me?

        I am quite sure you are aware of the scientific hypothesis on how the earthquakes were triggered. Is it recognised? Let me turn that around, has it been disproved?

        Aren’t you just a little bit curious as to why this cluster of earthquakes locate onto the same small fault that HH-1 is bored through?

        Residents here welcome other theories Judith Green other than “God did it, don’t know how”.

        • Dorkinian – my question was entirely reasonable. As we all know, correlation does not prove cause. You are using what you believe to be a spatial correlation to imply the cause of these tremors:. However, no one has provided any realistic mechanism to link the drilling activities to the tremors. To distance between the events and the well, as well as the small volumes of fluids and pressures involved mean that it is implausible that the two are linked

          • My apologies Judith I assumed you had read and undstood Edinburgh University’s hypothesis.

            I see you can’t have otherwise you’d know it has nothing to do injection.

            To summarise they noted continuous gas pressure build up and venting taking place during the 2016 well testing at Horse Hill, after which the well was “shut in” with the operator unable to continue or return due to planning restrictions, and the hypothesis involves the venting of the well causing sudden depressurisation of the connected and critically stressed fault. The operator will not provide ANY information to the University so this remains unproven.

            I hope that helps but if not please read and carefully consider their very detailed submission to the OGA workshop. You will find the link on the OGA website.

            • Paul if you mean the Edinburgh hypothesis, you should wait a little while until it is published as an academic paper and then state your proofs that it’s impossible there, where the authors and no doubt other specialists in this area will be able to discuss it with you. Don’t assume they trawl through the very mixed bag that is the comments section on DoD!

              I will look out for the discussion, should be interesting!

          • Re. “As we all know, correlation does not prove cause. You are using what you believe to be a spatial correlation to imply the cause of these tremors”

            I am not, I am saying that if the Davis Frohlich test had been answered fairly e.g. recognising a well 3 kms away from the largest event, the outcome would be a finding that they were probably induced and that should have led to a full investigation into the cause including access to operator records.

            • What do you do for a living Judith? Are you structural geologist? Another Professor (Emeritus, of Geophysical & Climate Hazards) told me that when a fault is critically stressed, the pressure needed to set off an earthquake could be as little as the pressure of a handclap.

              I’m not qualified to judge Professor Haszeldine’s work, I will let his peers do that, but I certainly respect the fact that he doesn’t succumb to OGA groupthink and has actually examined possible industrial triggers for the Newdigate Swarm.

              Given the wild inaccuracies in your previous posts I don’t think your understanding of the facts is sufficient for you to be dismissing considered research by respected academics.

    • Dorkian
      Thanks

      As HH continues to be worked on the timeline will need to be extended should any further tremors occur. I am not convinced the Professors links are valid, but time may tell.

      Re injection wells, it looks as if Angus prefer to ship the waste water to a reatment plant ( in the meantime is my guess ).

      • My pleasure, we have since learnt that Angus may need to take their waste water away however it is not Angus at Brockham but UKOG at Horse Hill that have produced a scoping enquiry outlining their plans for another four extraction wells plus an injection well at Horse Hill. This plan was then updated to include two injection wells in a subsequent RNS.

        Given the known correlation between injection wells and earthquakes and the fact that the region is now seismically active you might think that would be a problem? It seems not if the OGA can help it.

        Meanwhile thousands close bridges and demonstrate against the government’s lack of commitment to tackling climate change.

        Feels like the beginning of the end of an era but will it be in time?

        • Dorkinian, do you realise that arguing against injecting water underground will mean that many green projects would also be affected – geothermal, CCS, energy storage etc?

            • Sigh. No, I’m arguing against the plans for new disposal/ pressure support wells operating in the specific, recently seismically active area that is the subject of the article you are commenting on.

              Gosh Judith, you really are all over the place!

              First you thought the Edinburgh University hypothesis involves injection from Brockham, now you think this is all about fracking?

              For the record which operator do you think is “fracking in shale” here Judith?

  7. I see no mention of the very major fault that runs through Box Hill, Reigate and eventually into France,

    I remember this being discussed when I was reading for a degree in Mining Engineering at Leeds 60 + years ago.
    A major quake would surely be noticed in the Newdigate area.

    I should also mention that after graduating I have worked in oil and gas exploration and development around the world

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