People living in the area of Surrey hit by earthquakes last summer felt another tremor this morning.
The quake, measuring 2.4ML (local magnitude) happened at 7.43am and came as geologists from Edinburgh University pointed the figure at the Horse Hill oil site as a cause of 15 tremors in 2018.
The leading investor in Horse Hill, UK Oil and Gas plc, said there was “no reasonable scientific basis for the claims” made by the Edinburgh geologists and described one of the authors as a “well-known opponent of the oil and gas industry”.
But Friends of the Earth said the Edinburgh conclusions should “give the government pause for thought when considering calls by the industry to relax regulations on fracking-induced seismicity.
Today’s tremors shook furniture and was described as a “large bang”, “strong impact” and a “general rumble”. A second smaller tremor, measuring 0.2ML, was recorded 15 minutes later.
The epicentres were between Charlwood and Newdigate, north west of Gatwick Airport – the same area as the previous swarm. It was also estimated to be at the same depth, of 1-2km.
The 2018 earthquakes, which were unprecedented in this part of Surrey, began on 1 April and continued until 19 October. The strength varied from minus 0.4ML to 3.0ML.
Location of faults and earthquake epicentres. Source: Further Potential for Earthquakes from Oil Exploration in the Weald, by Dr Andrew Cavanagh, Dr Stuart Gilfillan and Professor Stuart Haszeldine, School of GeoSciences, The University of Edinburgh, 5 Feb 2019
In November last year, the Oil & Gas Authority ruled out human cause for the 2018 earthquakes. It said no work was being undertaken at the nearby Horse Hill oil exploration site and so it should be excluded from its analysis.
Horse Hill Developments Ltd (HHDL), which operates the Horse Hill well, consistently said its work did not induce the earthquakes.
But a paper by three Edinburgh geologists, released today, concluded:
“Our assessment supports the concern that Horse Hill oil exploration triggered the [2018] earthquakes.
“We infer that future oil exploration and production close to critically-stressed faults in the Weald is likely to result in similar earthquake events.”
Relationship between earthquakes and Horse Hill site activity. Source: Further Potential for Earthquakes from Oil Exploration in the Weald, by Dr Andrew Cavanagh, Dr Stuart Gilfillan and Professor Stuart Haszeldine, School of GeoSciences, The University of Edinburgh, 5 Feb 2019
The authors of today’s report, Dr Andrew Cavanagh, Dr Stuart Gilfillan and Professor Stuart Haszeldine, said they had evidence that there was work at the Horse Hill site when the quakes started in April 2018.
They said social media posts and responses to Freedom of Information requests indicated that well preparations for flow testing immediately preceded the Newdigate earthquakes.
One possible cause of the quakes could be the release of pressure at the Horse Hill Well site, they said:
“Prior to flow testing in April and July, Horse Hill appears to have encountered a natural source of overpressure in the gas-rich oils of the Kimmeridge, as observed in the ‘gas lift’ reported for the well.
“We infer that management of this pressure (probably by bleeding the well annulus prior to testing) likely altered the Horse Hill fault stress balance, which then impacted on the Newdigate fault, causing the earthquakes”.
They said the well and site engineering logs – which have not been made public – could provide more information on well intervention pressure changes as the trigger for the 2018 quakes.
The geologists said the 2018 earthquakes clustered around 1km below the surface, close to the intersection of the two faults.
The Horse Hill fault intersects the oil well at the same depth as the exploration targets and continues towards the Newdigate fault, they said. The authors described this intersection as “a likely conduit for pressure changes between Horse Hill and the Newdigate cluster”.
Relationship between faults and Horse Hill site. Source: Further Potential for Earthquakes from Oil Exploration in the Weald, by Dr Andrew Cavanagh, Dr Stuart Gilfillan and Professor Stuart Haszeldine, School of GeoSciences, The University of Edinburgh, 5 Feb 2019
They added that later earthquakes happened when flow testing work was underway on the Horse Hill site:
“the earthquakes in August and September coincide exactly with the deployment of a perforation gun downhole to improve flow.
“The pattern appears to be months of inactivity prior to well intervention and preparation for flow testing. The well interventions then precede earthquake activity by hours to days.”
The authors have sent their paper to Surrey County Council, which is currently consulting on proposals to drill four more oil wells and carry out long-term oil production at Horse Hill.
“Speculations dismissed”
Stephen Sanderson, the chief executive of UKOG plc, said today Professor Haszeldine had attended a workshop on the Surrey seismic events, organised by the OGA.
“Professor Haszeldine’s speculations for the cause of the Newdigate cluster were dismissed by all of the other 18 expert attendees at the OGA workshop. As well as the OGA’s workshop’s finding that there was no direct causal link to oil and gas activity, further scientific papers are to be published by experts in seismicity supporting the same conclusions.
“Even though they were provided with specific data by the OGA, Professor Haszeldine and his two colleagues have provided a completely incorrect timeline of HHDL’s operational activities. There was no ‘flow testing in April’. Flow testing at Horse Hill only began in July 2018.”
Mr Sanderson dismissed the Edinburgh statement that earthquakes in August and September coincided with the deployment of a perforation gun.
“Re-perforation of one of the oil reservoirs took place on 17 August 2018.
“Firing of a perforating gun is an event lasting milliseconds, not two months.”
Geolgist Dr Stephen Hicks, of Imperial College London, also dismissed the Edinburgh report:
“The report by Cavanagh, Gilfillan and Haszeldine presents a working hypothesis that lacks analysis of one of the key pieces of seismic evidence available: seismic waveform data from the earthquakes. This is available to everyone, including fellow scientists at: http://www.earthquakes.bgs.ac.uk/monitoring/data_archive.html“
He said the earthquake locations relied on by the Edinburgh geologists were “out-of-date” and should be updated to reflect the data from local seismic stations installed in July and August last year.
He added:
“As a rigorous and independent scientist, I am open-minded, but at present, there remains no significant physical explanation based on substantial evidence that could explain how these earthquakes could have been induced by human activities.
“Although a surprise to those living in the area and to us seismologists, the one silver lining of today’s magnitude 2.4 earthquake is that it is the largest earthquake which was recorded by all 5 local seismic stations, and the data from it can give us more confidence in our interpretations of the earthquake mechanisms. Analysis of the data is ongoing and this work will be submitted for formal, peer-reviewed scientific publication in the near future.”
“Pause for thought”
Friends of the Earth clean energy campaigner Tony Bosworth said:
“Today’s report linking earthquakes in Surrey last year to oil exploration should give the government pause for thought when considering demands from oil and gas companies to relax regulations.
“The government has said that the current system is fit for purpose. They must keep to this and not make further concessions at the first sign of complaints from a dirty, unwanted and unnecessary industry.”
“Company should make site information available”
Weald Action Group, a network of community groups opposed to oil and gas extraction in south east England, called on HHDL to provide the well and site engineering logs for the period of the 2018 quakes.
James Knapp, of the group, said:
“The Oil and Gas Authority appears to have been less than rigorous in researching what caused these quakes.
“Horse Hill Developments Ltd hasn’t provided the information that’s needed for a proper assessment and what information there is available clearly points the finger at their well site.
“With plans afoot for a massive increase in oil extraction at this site, this matter needs to be thoroughly investigated before any decisions are made.
“We support calls for a moratorium on drilling and on decisions on planning applications which might cause quakes. They have caused a lot of concern locally and the process of analysing the cause of the quakes has been far from transparent”.
“Caution needed in linking seismicity to oil operations”
Ken Cronin, Chief Executive of UK Onshore Oil and Gas (UKOOG), said:
“Last year Newdigate saw a number of similar shallow seismic events, leading the Oil and Gas Authority to launch an expert panel of geoscientists to review the evidence and determine the cause. They concluded that there was no causal link between the seismic events and oil and gas activity. In addition, the British Geological Survey prepared a report for the panel, noting that earthquakes are not unprecedented in the area and the events were unlikely to have been induced by oil and gas activity.
“Those drawing links between onshore oil development in the region and the latest seismic event should exercise caution in doing so. There will be a number of factors that have contributed to the recent seismicity in Newdigate, but to date, experts have concluded that oil exploration has not been one.”
Categories: Research
DRILL OR DROP? 
Martin got to love Stephen Hicks factual reply above 🙂 … any way, regardless of any replies….. Ruth Hayhurst does need to advise why she has not spoken with Stephen Hicks prior to posting the above report.
I thought they had been Flow testing from November at Horsehill?
Drill or drop is twisting the facts to suit her agenda again.
This tweet shows only that there is no expert consensus over depth but both given depths are extremely shallow and well within the sediment rocks which host the hydrocarbons, not in the deeper crystalline bedrock where you would expect to find naturally occurring earthquakes.
Perhaps while Dr Hicks and his friends rewrite their paper to include the Valentines day earthquake and the continuation of the swarm they should reflect on the fact that it was Edinburgh University that predicted it.
What is Ruth’s agenda then Tom ? She didn’t make anything up , there was a tremor today in Newdigate , BGS measured it at 2.4 with intensity of 3 , it was felt locally. The scientific paper was released today also , both things have been reported , which part has been twisted ? Doh !
Jono 🙂 Earth is in constant movements. You have hundred thousands tremors like this a year. You put your equipment anywhere and you will find some. But hey, it is better to report only those close to drill sites right? 🙂
Tim, siesmic monitoring equipment all around PNR, only registered earthquakes for ,18 months have been during or shortly after fracking!
Kindly leave the forum for spreading false propaganda!
Latest edition of the BP Energy Outlook just published.
Look at the chart on page 79:
“The transition to a lower-carbon fuel mix continues, led by renewables and natural gas”
Click to access bp-energy-outlook-2019.pdf
Look at the RHS chart on page 15
Looks like gas demand continues to increase past 2040 and oil won’t peak until shortly before then.
Expanding middle classes…….
Perhaps the unscheduled school holiday tomorrow will stop this? Or perhaps some of the 2040 demand don’t get a chance to go to school yet?
Perhaps we should stop drinking wine?
Pathetic Tom and Stephen Hicks, Seismologist.
These rabid attacks on Drill or Drop are getting tedious and regrettably predictable, the data appears up to date from the dates given on the graphics and your questions should be directed to the publishers of that data and not to Drill or Drop.
They are:
!Relationship between earthquakes and Horse Hill site activity. Source: Further Potential for Earthquakes from Oil Exploration in the Weald, by Dr Andrew Cavanagh, Dr Stuart Gilfillan and Professor Stuart Haszeldine, School of GeoSciences, The University of Edinburgh, 5 Feb 2019!
“Relationship between faults and Horse Hill site. Source: Further Potential for Earthquakes from Oil Exploration in the Weald, by Dr Andrew Cavanagh, Dr Stuart Gilfillan and Professor Stuart Haszeldine, School of GeoSciences, The University of Edinburgh, 5 Feb 2019”
i suggest you stop making scurrilous remarks about the messenger and take it up with the source and stop trying to shoot the messenger. though by all accounts, I understand that is one of Paul Tresto’s favourite activities.
I pity the postman where you lot live, it must be like trying to deliver post to a grumpy tiger tank?
i dont know, which is worse, industry hacks with a weight of chips on their shoulder or contributors with obsessive fog and red diesel fixations?
Unless this was some sort of twisted Valentine of course?
In which case you better get your yellow coat and hard hat…..the only thing you will be pulling tonight will not make the earth move for anyone……
“I understand that is one of Paul Tresto’s favourite activities. ” ??
Explain please – thanks in advance (I don’t really expect anything logical).
[Image removed due to copyright concerns]
Ooops – you are right. I do remember this – thanks for reminding me. I recall the messenger was not DOD? And definitely deserved shooting aka your excellent cartoon….
By the way the Wigan / Redman clue was genuine regarding where / how the TLS came about and the 0.5 was accepted. Perfectly understandable that you can’t pick up the connections but I thought one of the “experts” on DOD BB might?
Its a pleasure Paul, glad to be of service. Who is DOD BTW? Oh, you mean Drill or Drop, right, i though Ken had passed to that great giggle factory in the sky.
Not the grocer then? I was beginning to think it was the source of all those bags of flour and melons falling to the floor and his delivery van ran over all those manhole covers in the road? Must have gotten around a lot too, all those lonely ladies on the round? Well someone did have to stand in for the milkman i suppose….
Maybe the hint was just a bit too vague and remote? Not the intention i am sure…..??
What happened BTW, did they manage to turn the TLS from red to green? Cut off at 48 on the Richter scale? A simple switch would have sufficed, as i am sure they are working on one right now, just like the police having one that changes traffic lights from red to green when they are in a hurry?
Are you in a hurry? Maybe a siren and flashing lights will be added to the rig too? Then at least people will have a moment to rush around and save their bone china and put the kids under the bed before it all comes crashing down….
PhilC As long as the gate is closed and the dog is on the inside the Postman is happy…
I used to carry out surveys for a local authority for a new drainage system, the houses were all on cess pits and small treatment tanks. During that i had to go around and survey each properties on site drainage system. Many of them had dogs, some just wanted to play, others were aggressive.
We were taught to totally ignore the dog, no matter how loud and aggressive it got, because the pack leader always ignores a pack member. It worked every time, i never made eye contact and totally ignored them and they either fell silent or they went straight for my colleague who had the same training but was scared of dogs and they knew it.
The only dog i ever had to avoid was in a gravel road, it arched its back and bared its teeth and had its tail up between its legs.
Thats how i imagine some of the posters on this blog, most of them you can just ignore, but there are some that arch their verbal back and tuck their verbal tail between their legs.
I see one now.
Obsessive for reality rather than fiction.
Try it some time. Giggle around red diesel-or just ask a farmer. They are quite a wise bunch, as Osborne found out when canvassing and having walked a great distance up the road to a farm found a farmer.
“Long road to get to your farm, Mr. Farmer”.
“If it was any f****n shorter, then it wouldn’t reach.” Said Mr. Farmer.
Reality is often pretty straight forward.
See what i mean…….
See what i mean again….
It’s amazing how people accept the opinions of the geoscientists who have no experience of seismology or geomechanics instead of listening to the experts in this field. As the report mentioned, a workshop was held on this subject and the least qualified person there, Stuart Haszledine, was the only one who argued that these tremors were caused by Horse Hill operations.
I remember one tremor was next to HH when there was only truck on site. No activity what so ever. But hey, who will remember that? [Edited by moderator]
Tom – what many of the antis on here don’t realise is that the experts in this field are not only super bright but they’ve often had 30 man years experience looking at earth tremors. However, for some reason they chose to rely on their instincts or trust the views of rather verbose amateur geologists who seem to regard themselves as polymaths because they have written crap on a range of subjects
Tom are you suggesting seismic activity needs to be instantaneous to be linked?
No Lisa C-but AFTER activity rather than before.
Now, if it was before, that would be a whole new can of worms. Oops-don’t tell them.
Martin collyer, AKA Tom?
No Fifi, aka Eddy Stone-shining a light through the fog for all the lost souls!
I stayed in Africa for a while visiting a colleague and went on a couple of weekend trips to the great plains and to Kilimanjaro.
The animals could tell when the rains were coming and the elephants could sense changes in the weather and the earth. Sometimes the rains washed away great swathes of earth and that flooded over the plains like a dirty tide. The animals would always move up to the slopes of the mountains the day before that happened. so when we went looking for animals they were up on the slopes and not on the lower plains.
I heard that when the tsunami hit in Indonesia a couple of years ago, that the elephants who normally browsed on the coastline, moved up to the higher slopes just hours before the tsunami hit and would have washed them out to sea.
I dont recall them having any academic qualifications though. Funny that.
People dont need academic qualifications to know whether something is dangerous or not, its instinctive and it is invariably accurate and should not be ignored.
Do we need qualifications to be born, or die, or walk or ride a bike, or eat and drink and breathe?
No, of course we don’t.
I know some very well qualified people, far more so than myself, some of them i would trust to change a light bulb without a safety harness, other people who have few academic qualifications are the best engineers i know, they just never needed or had the opportunity to go through the academic stage and have not needed to since.
I believe there is as yet no explanation for these tremors, Judith.
The scientific method (as I understand it) involves advancing hypotheses which are then criticised or accepted by others. Looking at the comments on this article, Dr Hicks appears to be the only person to have advanced any meaningful criticism on the hypothesis that the tremors may be linked to Horse Hill.
Paul – the tremors at Horse Hill are natural – that’s a perfect explanation
I’m no expert in geology, so I leave such analysis to said experts. However, when a substantial number of untypical seismic events occur in a small area, it is natural and logical to look at what other activity has been happening in close proximity that could have caused them. In this case, the O&G activity at Horse Hill fits the bill and it should therefore be a prime candidate, with the onus on both experts and the operators to disprove any connection and, by extension, be able to provide firm evidence that natural causes are to blame. This cannot realistically be done without evidence from activity logs at the site. It is therefore surprising that, quote ‘the well and site engineering logs – which have not been made public – could provide more information on well intervention pressure changes as the trigger for the 2018 quakes.’
I trust these logs will be/have been made available to anyone tasked with finding the true cause of said seismicity.
Isn’t it important that EVERY expert opinion on possible causes are closely scrutinised and the necessary evidence used to confirm or deny that possibility, irrespective of how many people put forward such a theory?
Perhaps Judith Green has both the necessary expertise and access to the logs that would be necessary before even thinking of making the claim ‘the tremors at Horse Hill are natural’.
Mike, I’ve just gone through all of the presentations made at the workshop and it’s very clear cut. The low volumes of fluid movement/pressure changes, combined with the large distance for the operations from the hypocentre strongly suggest that these tremors were not related to the operations. Tremors are random events so you would naturally expect them to be clustered.
Of course Mike, the other activity that fits the bill is the constant activity at Gatwick Airport!
Are you saying that it makes no sense to analyse these seismic events in conjunction with the logs of activity at nearby Horse Hill Judith (or do you have personal access to data that hasn’t been made public, and why is that)? That doesn’t strike me as scientific or remotely sensible. If the logs were not used as evidence in the said presentiations, then I wouldn’t consider their conclusions or hypotheses to be particularly robust. I mentioned that I’m no expert, but if seismic activity in a particular area is rare, I would expect clusters to be even more rare and would be looking very carefully at EVERY credible source, not immediately ruling out an obvious source with crossed fingers.
Thanks for your helpful suggestion of constant activity at Gatwick airport Martin. I’m sure the expert seismologists will be allowed access to logs of aircraft activity there and will find it useful to see which of the cluster of events near Horse Hill coincide exactly with aircraft landing. However, they may struggle to explain exactly why a handful of landings cause earthquakes when decades of other landings don’t. Could someone please pass Martin’s suggestion on, as I’d rather avoid the inevitable ridicule.
A lot of the flat earthers were not that qualified-and were still wrong.
A lot of frack earthers are right here.
No qualifications required for the Darwin Dumb Ass award.
Though apparently they think it helps….
This pattern of quakes & tremor is remarkably similar to what happened in Groningen, N Netherlands. People I spoke to who live there said there were often gaps of several months and the quakes gradually increased in intensity. Look on the net to see photos of damage: is this what we have to look forward to?
Judith Green
Regarding fracking related earthquakes as the BGS call them, a swarm of nearly 60 struck the Fylde Peninsula starting when fracking at the Cuadrilla PNR fracking site started last autumn and finishing when the fracking was halted.
No other onshore earthquake activity recorded before or after on the Fylde for several years.
Cuadrilla have readily stated that THEY caused the Preese Hall earthquakes 8 years ago and the PNR earthquakes last year.
Stop repeating industry propaganda that just isn’t true please. You just embarrassing yourself.
Thank you.
Peter – where did I say that the tremors at PNR we’re not caused by fracking? I simply claimed the ones at Horse Hill were not related to operations there