The seventh earthquake in just over three months was recorded in part of Surrey at midday today.
It was the most powerful earthquake so far, with a magnitude of 3.1, the British Geological Survey (BGS) confirmed.
A residents group has urged the BGS to investigate any possible links with the local oil and gas industry.
Brockham Oil Watch said in a letter to the BGS:
“We think that serious questions should be asked and investigated, especially in connection with the two [oil and gas] sites nearest to the epicentres: Brockham and Horse Hill.”
Their call was supported by the Green Party MEP for the area, Keith Taylor. But UK Oil and Gas, the main investor at Horse Hill, near Gatwick, said there had been no sub-surface work since 2016. The operator of the Brockham site, near Dorking, did not respond to our request for comment.
This morning’s earthquake was felt by people in Newdigate, Dorking, Horley and Charlwood. They reported creaking buildings, shaking ground and moving lights.
The BGS has confirmed that this morning’s quake followed three previous ones recorded since 1 April 2018. They had a magnitude of 2.7, 2.6 and 2.4. There were also three smaller quakes of 1.5-1.8 magnitude in the same area over the same period, it added.
Before the recent seismic activity, Surrey had been earthquake-free for 50 years.
After the previous earthquake on 29 June 2018, the BGS said on its website:
“We are unable to say categorically if these earthquakes are related to hydrocarbon exploration or production in the Weald, mainly because of the uncertainties in our estimates of the earthquake epicentres and depths.”
The BGS said it was well known that hydrocarbon exploration and production could result in man-made or induced earthquakes. They were usually linked to long-term extraction or injection of fluids, such as fracking or waste disposal, it said.
Flow testing is due to begin at Horse Hill. But the BGS said it was unlikely this would result in induced seismicity.
At Brockham, there is an injection well, which is used to dispose of produced water. The Brockham site was closed for much of 2016 and 2017, resuming production in spring 2018.
Data from the Oil and Gas Authority shows that water reinjection at Brockham began for the first time in March 2018.
Brockham Oil Watch said:
“The convergence of the Horse Hill flow test, resumed operations at Brockham and the earthquakes is at the very least puzzling.
“We think that there are too many unknowns and that the link should be thoroughly investigated before the drilling and injection can continue.”
“Well integrity should be tested as well to check if the earthquakes didn’t cause damage that could lead to environmental pollution.
“This is critically important at a time when Surrey is facing a proliferation of applications for hydrocarbon exploration and production, including in some of its most precious areas of outstanding natural beauty.”
Keith Taylor, the Green Party MEP for south east England, said:
“Details may be scant at the moment, but 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. The links between earthquakes and the unconventional onshore oil and gas drilling industry are well established.”
“I wholeheartedly support the calls for the British Geological Survey to further investigate this activity and would add that it seems only sensible to put a moratorium on any oil and gas activity in the region until the results of the investigation are clear.”
“The oil gas industry must surely agree that any connection between onshore oil and gas drilling in Surrey and Sussex and the recent spate of earthquakes can only be confirmed or dismissed after it has been independently investigated.”
Stephen Sanderson, executive chairman of UK Oil and Gas, said:
“There has been no subsurface activity at Horse Hill since March 2016.
“We are currently preparing to conduct a flow test using a crane. No flow has yet taken place. “We are not drilling and operations utilise a crane not a drill rig.
“We should stress that the work we are planning has the same seismic impact as any type of construction work requiring the use of such a crane. 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.”
DrillOrDrop asked Angus Energy for more details on water reinjection at Brockham and its view of any link between local seismic events and oil and gas activity. This post will be updated with any response.
Timeline of largest earthquakes in the same area of Surrey
1 April 2018: 2.7 magnitude
27 June 2018: 2.6 magnitude
29 June 2018: 2.4 magnitude
5 July 2018: 3.1 magnitude
Also three smaller earthquakes of 1.8. 1.7 and 1.5 in same location.