The risk of earthquakes from well operations such as acidisation, water reinjection and pressure release should be controlled in the same way as fracking, a parliamentary meeting heard today.

MPs and peers were hearing evidence on whether the rules on fracking-induced seismic activity should be changed. The industry has been calling for a relaxation of the traffic light system after Cuadrilla’s Lancashire fracking operation induced more than 50 earth tremors last autumn.

The traffic light system currently requires operators to pause fracking for 18 hours if there is a 0.5ML (local magnitude) earth tremor. But it applies only to the shale gas industry.

Three witnesses giving evidence to the All Party Parliamentary Group on shale gas impacts said the 0.5ML threshold should also be applied to seismicity caused by other oil and gas operations.

They referred to 28 earth tremors Surrey in the past year, measuring up to 3.1ML on the local magnitude scale.

Chart of the 18 July 2018 Newdigate earthquake. Source: Stephen Hicks

The tremors were centred on Newdigate, 3km from one oil exploration site and 8km from another. The two companies that operate the sites have repeatedly said they did not cause the earthquakes. And all but one of a group of geologists, at a meeting organised by the Oil and Gas Authority (OGA), concluded that the earthquakes were natural.

But Jonathan Essex, a member of Surrey County Council, told this afternoon’s meeting that the oil industry in southern England was less well-regulated than other hydrocarbon exploration and extraction operations.

“Whereas the traffic light system stops activities when an earthquake above 0.5 is felt in the proximity of fracking, here in Surrey the effects of earthquakes even over 3 on the Richter scale (which means over 1000 times more powerful, as this is a logarithmic scale) cause no changes in drill site activities.

“There is no regulatory requirement to disclose what chemicals are being used, in what quantities, and what activities are taking place on site, and when.

“We are asking for the traffic light system to be extended to not just cover hydraulic fracturing but other operations including acidisation, water reinjection and pressure release.”

Cllr Essex presented 20 statements about damage from the Surrey earthquakes. The first event, on 1 April 2018, reportedly caused a 50m long landslip, 10km from the epicentre. It removed half the garden area of three properties. Many trees had to be taken out because roots had been undermined. The cost of the remedial work has been estimated at £600,000.

He said four houses had suffered vertical cracks to walls and 10 properties had cracks to more than one wall. He said:

“Residents are concerned and angry. They feel powerless. They feel let down by inadequate regulation.”

James Knapp, of the Weald Action Group, which opposes oil drilling in the region, called for a mandatory setback or respect distance for drilling near faults.

“Our view is that if earthquakes can be stopped they should be, therefore the protection of the Traffic Light System should be applied nationally so its protection is available when unexplained earthquakes occur.”

The Weald Action Group has supported calls by the Conservative MP for Reigate, Crispin Blunt, for an independent inquiry into links between the Surrey earth tremors and the local oil and gas industry.

Professor Stuart Haszledine, of Edinburgh University, the one dissenting voice at the OGA meeting, said seismicity could not be regulated adequately in the UK because there was a lack of evidence.

He and two Edinburgh colleagues had also called for an independent investigation into the seismic swarm in Surrey earth tremors. He said:

“One of the roles of government is to safeguard the interests of the public. The government cannot take a view on that when the information is held by the operators who refuse to release data for scientific debate.”

He criticised Cuadrilla and UK Oil and Gas or not releasing information from their Preston New Road and Horse Hill sites.

“For a company [Cuadrilla] to be sitting on 40,000 data point and not release them is not helpful

“For a company [UKOG] to sit on a history of pressure measures is not helpful.

“I do not think we have understood the process. I do not think we are having a proper scientific debate.”

Seismic events at Cuadrilla’s Preston New Road shale gas site up to 14 December 2018. Source: Refracktion

Susan Holliday, chair of Preston New Road Action Group, which opposes fracking at Cuadrilla’s shale gas site near Blackpool, also made the case against relaxing the regulations.

New information from the Preston New Road, analysed by DrillOrDrop, shows that Cuadrilla carried out only 15 main fracks on just a third of the planned stages of the well. Fracking used a fraction of the proposed fluid and proppant and paused for a month because of mechanical problems.

Mrs Holliday described the biggest tremor caused by fracking on 11 December 2018:

“At about 11.20 I heard a bang. I assumed there had been a bump on the road outside, so I went to look out of the window, but there was nothing to see.”

The British Geological Survey later confirmed there had been a 1.5ML tremor at 11.21. It was the ninth in a series of tremors that morning.

Mrs Holliday said:

“We strongly believe that the Traffic Light System should be kept to the current agreed levels. It is there to protect people and the environment.

“Much research went into setting these limits and around four weeks of experience of one partially fracked well cannot provide enough data to cause the limits to be changed.”

Cuadrilla agreed to the traffic light system after causing the earthquakes by fracking the Preese Hall well in 2011, she said.

“We find their demands to relax the controls a dangerous precedent and one that would cause great concern for our community.

“We believe that if Cuadrilla is unable to operate under the regulations that they initially agreed to, then they should not continue. People’s safety must come before commercial interests.”

Her case was supported by Tony Bosworth, energy campaigner for Friends of the Earth. He said:

“Government should not give in to pressure from the industry to change the traffic light system. It was put in place to protect people and the environment. Industry accepted the regulations right up to the point that they came to frack. Moving the goal posts at this point will only weaen confidence in the regulatory system.”

“Limit can be relaxed safely”

But two geologists argued that the traffic light system could and should be relaxed.

Dr Brian Baptie, of the British Geological Survey, repeated his argument that there would be little risk to people if the 0.5ML threshold was raised.

“It was intended as an interim measure. It was always said it could be relaxed or made stronger when there was more data available.”

He contributed to a government-commissioned report which proposed the 0.5ML threshold. He said there was now extra data on fracking-induced seismicity.

The 0.5ML threshold was conservative and lower than the limits used in parts of north America, he said. It did not reflect risk of damage or public concern.

Asked by the group’s chair, Lee Rowley, whether there would be more or stronger earth tremors when Cuadrilla carried out full fracks along the entire length of the well at Preston New Road, he said:

“The more you inject, the more earthquakes you will get and it will increase the probability of risk.”

Dr Baptie said a pause to fracking would not necessarily stop seismic activity. But he added that earthquakes with a magnitude of less than 4ML did not usually cause damage.

He said a revised traffic light system should be risk-based and could incorporate ground velocity and motion, as well as magnitude.

Dr Nick Riley, of the geological consultancy Carboniferous, called for an incremental increase in the threshold for the traffic light system.

“0.5 was advisory subject to more data being acquired. We will not learn any more unless we raise the threshold.”

He said the threshold could be lower in more densely populated areas or to reflect ground conditions. He said wells could be deformed by seismic activity – as happened at the UK’s first high volume hydraulic fracture at Preese Hall. But he said that does not mean that a well has lost its integrity. He said a 7ML natural earthquake in Japan did not a damage a well.

“You learn this by doing”, he said.

• The APPG said it invited the Environment Agency,  Health & Safety Executive and Oil & Gas Authority and shale gas companies, including Cuadrilla, to the meeting but they did not attend.

Reporting from this meeting was made possible by donations from individual DrillOrDrop readers