The British Geological Survey has revised upwards the intensity of the UK’s most powerful fracking-induced earth tremor from “strong” to “slightly damaging”.
The bank holiday tremor caused by Cuadrilla’s fracking operation near Blackpool was upgraded today from an intensity level 5 to level 6.
The 2.9ML tremor, centred close to the Preston New Road shale gas site, is the largest induced by hydraulic fracturing in the UK. It was among 119 tremors caused by fracking at Preston New Road since 15 August 2019.
The BGS uses the EMS Intensities scale, which describes a level 6 as “slightly damaging”:
“Felt by most indoors and by many outdoors. Many people in buildings are frightened and run outdoors. Small objects fall. Slight damage to many ordinary buildings eg fine cracks in plaster and small pieces of plaster fall.”
People reported feeling the tremor, which happened at 8.31am on 26 August 2019, from as far away as Preston and Chorley. There were complaints of houses shaking and cracks to plaster.
Intensity 6 earth tremors are not common in the UK and it is unusual for a magnitude 2.9 tremor to have an intensity of this size, the BGS told DrillOrDrop.
The intensity of a 2.1ML tremor, on 24 August 2019, has also been revised up from level 3 (weak) to 4 (largely observed). A report on Cuadrilla’s website likened this tremor to a toddler playing on a wooden floor.
A spokesperson for Preston New Road Action Group said:
“These revised intensity levels reflect the amount of impact that Cuadrilla is having on the lives of people across the Fylde Coast.
“They should no longer trivialise the impact of these earthquakes using analogies to shopping, fruit or toddlers as people now know what these earthquakes really feel like.
“Similarly comparisons with construction sites are not helpful as we are not aware of any that cause such widespread impact as the site at PNR and at such unsociable hours”.
The campaign group, Frack Free Lancashire, has said there have been many reports of damage. In a letter to the local MP, the group said:
“We have been inundated with hundreds of messages and emails from concerned residents sending photographs of damage their property has incurred from the recent earthquakes caused by fracking at Preston New Road.
“The insurance questions are already pouring in also.”
There are also now suggestions that places further from the site may have been more seriously affected than those nearby.
A retired senior geography teacher said:
“Emerging evidence shows St Anne’s was much more affected than the area next to the site.”
She said St Anne’s was built on sand. Liquefaction and subsidence were a “massive issue” in the town, she said.
“The shock waves are much more amplified in unconsolidated matter and the worst situation is a sand-based substrate.”
Reports suggest that people living in rural Fylde experienced the tremor as a brief 1-2 second movement. But in St Anne’s, people reported the ground swaying for several seconds.
Within hours of the tremor, the industry regulator, the Oil & Gas Authority (OGA), suspended fracking at Preston New Road.
The OGA, Environment Agency (EA) and Health and Safety Executive (HSE), published a newsletter on the tremors today. (See right – click to enlarge). This said:
“Operations will remain suspended while the OGA gathers data from this and other recent seismic events. It will then consider carefully whether or not hydraulic fracturing operations, mitigations and assumptions set out in the operator’s Hydraulic Fracture Plan continue to be appropriate to manage the risk of induced seismicity at the Preston New Road site.”
The EA said there was no evidence to suggest that the seismic events had resulted in “any environmental harm”. The HSE said it had reviewed site data and was “satisfied that there are currently no well integrity issues”.
Mark Menzies, Conservative MP for Fylde, and the Labour MP for Blackpool South, Gordon Marsden, both called for a permanent stop to fracking.
In a letter to the energy minister Kwasi Kwarteng, Mr Menzies said he had been contacted by “a considerable number of local resident,s including several who have reported damage to their properties”.
Mr Marsden wrote to the environment secretary, Theresa Villiers, demanding an independent investigation into the tremors and damage caused by them. He said:
“We cannot let this go on any longer and risk further potential damage and unsettling of local people.”
More than 400 opponents of Cuadrilla’s activities at Preston New Road gathered outside the site entrance on the afternoon of the 2.9ML tremor.
Another protest is proposed on Saturday 31 August unless fracking is banned by Friday 29 August 2019.
DrillOrDrop reported that the industry regulators had been warned, before fracking started, that tremors were likely.
The predictions were made by Dr Grant Hocking, an American hydraulic fracturing expert. He said today:
“If induced tremors are experienced and are being felt in highly populated areas then those induced events are too large.”
Dr Hocking said:
“At Preston New Road, Cuadrilla are not commercially-fracture enhancing the shale, so they should not be doing it.
“Cuadrilla are simply pumping fluids into the subsurface, lifting the overburden, and giving rise to large >1.0 ML induced events, which the UK regulatory agencies should have the technical expertise and management backbone to stop.”
The BGS database lists 39 tremors at level 6 or more since 1900. The BGS said a level 6 tremor occurred in the UK approximately once every 10 years. The most recent level 6, in 2008, was at Market Rasen, in Lincolnshire. Four church spires were damaged and the bill for damage was £30m.
- DrillOrDrop invited Cuadrilla to comment on today’s revised intensity level. We also asked the company how many reports of damage it had received. This post will be updated with any response. We asked the Department for Environment, Food and Rural Affairs for a comment on Mr Marsden’s letter and will report any response.
Updated to give details of the EMS Intensities scale
This raises the question, Ruth, – does the BGS actually use the Mercalli Intensity scale, as favoured (or favored!) in the US? Or do they use the European Macroseismic Intensity Scale as shown on their website?
It might seem of academic interest, but IF fracking continues now we have our interest shifted from magnitude, which may have more implications for well security, to ground intensity, far more important to people, we should be clear on what we are discussing, or more pertinently how the BGS clasified earthquakes – even if there is little difference between the two scales at this level.
We did not need Dr Hocking’s report to predict earthquakes in the Fylde. Others have tried to point out over years that the Fylde geology is inadequately known, Cuadrilla’s assessments were deficient, and the recent swarm was inevitable, given the faulted nature of the geology. It frankly beggars belief that the company should have been lobbying for a reduction in regulation (i.e. the TLS) at the same time as unknowingly or knowingly putting local residents at risk even under the current regs.
I previously used to refer to “seismic events” as being a less combatative term than “earthquake” but having personally experienced the Saturday morning event I have no compunction at all in describing that as an earthquake. I am only glad my own home was no nearer to PNR.
What I think we can now say is that local residents (I am now including people living 5 miles or more from the site) are no longer convinced, even if they held the view before that fracking might be a good thing, that a ban – call it a moratorium if you will – is not a good thing.
Blackpool folk are not “frightened”. They are not the sort to be be fearful once they understand what’s going on. Now they do. They are angry. St Anne’s folk might well think long and hard about the quote from “a retired senior geography teacher” even if they agree with me an unattributed source like this is worthless.
BGS have confirmed to us that they do use the EMS when considering intensity.
As you say, intensity may be more relevant than magnitude when it comes to the effect on people.
Francis Egan has argued in the past that we should consider ground motion (which is linked to intensity) rather than magnitude for a seismic event, and Cuadrilla’s dropped shopping, passing trams and playing toddlers was perhaps an attempt to shift the debate in this direction.
Thanks Paul, that clarifies that.
I am amused sometimes though by the idea that dropping a shopping bag of a small frying pan is in any way related to the reality of an earthquake – which as we have seen can have ground effects over hundreds of square kilometers and more from one relatively minor magnitude event.
On the other hand I am appalled that the industry should try and con the gullible. What has been said before by Cuadrilla and their henchemn is not an attempt to shift debate, it was an attempt to shift public opinion against those opposed to fracking. To make them seem peddiling some sort of hysterical doomsday scenario. What is now clear is that those days are over. Ordinary people on the Fylde coast now understand what an earthquake is, how it could affect their lives and property, and how fracking is not something they are comfortable with. They will not be easily conned in future.
How many retired senior school geography teachers can there be living on the Fylde? However many I’m sure they are all thinking similar evidence based thoughts.
I’t doesn’t really matter how many or who they are.
What does matter is that this educated, intellugent and life experienced lady of the Fylde personaly experienced the 2.9 Richter Scale earthquake. She then deduced that this wasn’t a good thing due to the particular geological make-up of the Fylde meaning the coastal edges were surorisingly likely to be worse affected than those nearer the Cuadrilla fracking site at Preston New Road, Little Plumpton in Rural Fylde.
Good luck to us all, we’re going to need it in these troubled times! For one reason or another!
The comments from Dr Grant Hocking are interesting.
That being that Cuadrilla were using sufficient pressure to lift the overburden, without inducing suitable vertical fractures to ‘commercially fracture-enhance the shale’.
A point relating to overcoming the overburden pressure was noted in past DOD comments, though not directly relevant in this case maybe ( towards the end of the comments ).
Either way I suspect that fracking in the fylde will not restart.
Even if Cuadrilla move to the low risk approach suggested by GeoSierra ( see page 16 )
Click to access 122554754.pdf
Hopefully the review noted above will provide more information on the aspects of Cuadrillas frack plan vs the other views on it for the non experts amongst us who read DOD.