People living near Newdigate in Surrey reported feeling another earth tremor this evening.
The tremor was recorded by the British Geological Survey at 5.03pm and measured 1.9ML (local magnitude).
It follows a larger seismic event in the same area at 7.43am on Valentine’s Day (14 February). This measured 2.4ML and was described by residents as a loud bang, rumbling and shaking, as though something had fallen on their homes.
The latest tremors bring to 18 the total in an area of Surrey that had not previously experienced earthquakes for at least 50 years. The largest so far measured 3.0ML on 5 July 2018.
Described as a swarm by geologists, the tremors began on 1 April 2018 and continued during the summer until October 2018, when they stopped, only to resume last week. They have all been at approximately the same depth, unusually at about 2km, and in the same area.
The cause of the tremors has divided geologists. A majority of participants at a workshop by the Oil and Gas Authority concluded there was no evidence that the hydrocarbon industry in the area had induced the seismic activity.
But three geologists at Edinburgh University, including one who disagreed with the OGA workshop conclusions, said last week the link to local oil exploration should be investigated.
They released a report, written before last Thursday’s tremors, which concluded that operations at the Horse Hill oil site near Gatwick Airport could have triggered the 2018 earthquakes. They warned:
“We infer that future oil exploration and production close to critically-stressed faults in the Weald is likely to result in similar earthquake events”.
Their report was criticised by the major investor in the Horse Hill site, UK Oil & Gas plc, and the industry body, UK Onshore Oil and Gas.
Dr Stephen Hicks, of Imperial College, who installed seismic monitoring equipment in the area after the early earthquakes, said:
“there remains no significant physical explanation based on substantial evidence that could explain how these earthquakes could have been induced by human activities.”
He tweeted this evening:
“Surrey continues to rumble away this evening with a small and slightly felt magnitude 1.9 earthquake reported by the BGS at approx 1700 this eve. Follows last Thursday’s magnitude 2.3 event. Same location and depth as the previous events in the sequence.
Environmental campaigners said the process of analysing the cause of the earthquakes had been “far from transparent”. The Weald Action Group, a network of community groups opposed to oil and gas extraction in south east England, called on the Horse Hill operator to provide well and site engineering logs for the period of the 2018 tremors.
Yesterday, UK Oil & Gas announced that oil production from the Portland formation at Horse Hill had resumed after a six-month shut-in of the well.