The strongest earth tremor so far in the latest swarm in the Newdigate area of Surrey was felt across southern England early this morning.
Residents said shaking of buildings and furniture woke them up. The effects were reported from London to the south coast.
It has prompted a local campaign group to call for an investigation into the cause to be reopened and to look again at links with oil exploration at the Horse Hill wellsite near Horley.
The tremor, at 3.42am, was initially thought to be 3.6ML on the local magnitude scale but recorded first by the British Geological Survey at 3.0ML and later 3.1ML. The intensity – measured on a scale from 1-12 based on observed effects – was initially recorded at four and later increased to five.
It has the same epicentre and approximate depth as previous seismic activity in the area. The magnitude exceeds the previously strongest event measured at 3.0ML on 5 July 2018.
Two other small earthquakes in the area, measuring -0.5 and -0.6 were also recorded early this morning. Together they bring the total number of seismic events at Newdigate to 21.
Seismologist, Stephen Hicks, who has installed monitors in the area to collect more data, said:
“Looks like another strongly felt earthquake as part of the Surrey seismic storm this morning at about 3.42am.
He said an audio recording, sent by a Charlwood resident from the homes CCTV system, showed the distinct rattling of the initial p-waves followed by S-waves less than a second later.
The tremors began on 1 April 2018 and continued through the summer until October. They resumed this month with two tremors on 14 February (2 tremors) and one on 19 February.
The Newdigate area had not previously experienced earthquakes for at least 50 years.
The cause of the tremors has divided geologists. As DrillOrDrop reported, a workshop by the Oil and Gas Authority concluded there was no evidence that the local hydrocarbon industry had induced the seismic activity.
But three geologists at Edinburgh University, including one who attended the OGA workshop, concluded before this month’s earth tremors:
“Future oil exploration and production close to critically-stressed faults in the Weald is likely to result in similar earthquake events.”
Asked on BBC Radio Surrey this morning whether drilling at Brockham or Horse Hill could be responsible for the earthquakes, Stephen Hicks said:
“We’re keeping an open mind on that, based on any available new data that comes through. Let’s see what this recent earthquake shows and what has been taking place at the nearby oil drilling sites.”
The Weald Action Group, which campaigns against oil drilling in southern England, said in a statement this morning:
“This latest earthquake is consistent with the findings of experts from the University of Edinburgh, that the Newdigate Swarm may have been triggered by activities at the Horse Hill well site.
“They predicted that the Swarm would continue and the earthquakes could increase in intensity.
“The Oil and Gas Authority inquiry into the cause of the earthquakes disregarded the Horse Hill site, and so found the cause to be natural.
“Local residents are very concerned, we do need to get to the bottom of this and we would encourage them to write to their MPs formally asking for the OGA inquiry to be reopened, but taking into account the possibility of Horse Hill as a cause.
“There is a planning application for expansion and long term production at Horse Hill, which residents can still object to on Surrey County Council’s website.”
People across a wide area of Surrey and West Sussex took to Twitter to report their experiences.
— Al-E Nor-E (@Arthur_Grole) February 27, 2019
— Darren Hopkins (@darrenhoppers) February 27, 2019
— danielle wayland (@snappie30) February 27, 2019
@BrockhamWatch @surreymirror @BritGeoSurvey @BGSseismology @MoleValleyDC @newsmolevalley Scary, woke us (and the birds in the trees outside) with a start, really shook the house and we are near Dorking #earthquake #surrey #fracking https://t.co/geYVvNZKLh
— Fay Cooper (@A6FVC) February 27, 2019