Earthquakes linked to nearby oil extraction fracking sites

A series of earthquakes rattled parts of Surrey from 2018 into early 2019, catching many people off guard. Residents in Newdigate reported cracked walls and swaying furniture at odd times, raising questions about what could cause such unexpected disturbance. 

Scientists stepped up their investigations and discovered a curious link between these seismic events and an oil extraction site several miles away.

Surrey’s earthquakes raised questions

More than 100 small earthquakes occurred over a short span of time in Surrey.

They measured between 1.34 and 3.18 in magnitude, which is mild on the seismic scale but still disruptive for homeowners living through them. 

Geologists debated for a while whether the quakes could be connected to a nearby well or if they were simply natural activity. The site in question was located about three to six miles from the affected area.

Possible earthquake links to oil extraction

Dr. Matthew Fox, a lead investigator from University College London (UCL), investigated whether the quakes were triggered by oil extraction activities.

He and his team applied a mathematical model to assess how much the timing and volume of drilling might influence seismic events.

They ran over a million simulations and found a rough match between the well’s pumping schedule and the pattern of tremors.

“Our study suggests there is a link between the ground earthquakes and oil extraction at Horse Hill but we cannot rule out that this link is a coincidence,” said Dr Matthew Fox at the end of his team’s analysis.

He pointed out that more data is needed to confirm a cause-and-effect relationship.

Underlying pressures

Scientists have long recognized that removing oil or other fluids from rock can change pressure underground. This subtle shift can travel several miles through cracks and porous rock layers. 

The specific pace depends on how permeable the surrounding geology is, and even slight stress can set off a sudden slip along a fault.

Researchers suggest that certain types of rock might transfer pressure changes in the matter of a few days, while others could take much longer to show an effect.

Ongoing debate

The British Geological Survey (BGS) and other authorities continue to study seismic activity in that region of England.

Some experts believe the quakes were linked to a deeper fault that may have been ready to move anyway. Others see potential ties between drilling and the earth’s movement. 

“There has been no significant seismic activity in Surrey for decades, so these earthquakes were unusual events,” said Professor Philip Meredith at the end of his review.

He added that there is still a possibility the timing is just chance. The debate highlights that the mechanisms behind induced seismicity can be complex and require thorough data before reaching any firm conclusions.

Legal and community impact

Local planning authorities eventually quashed permission for further work at the Surrey site in October 2024. Another project in West Sussex is facing legal scrutiny as well, with residents pushing for careful assessment before exploratory drilling moves forward. 

These developments reflect a broader effort to balance the economic interests of energy projects with the concerns of people who live nearby. The legal challenges question whether a region’s full environmental and seismic context is being given enough weight before such operations begin.

Oil company insists the earthquakes were natural

Operators at the Horse Hill site have stated that earlier findings from seismologists satisfied the view that the earthquakes were natural, caused by a deeper and unconnected fault. 

“This is an incident that was answered and dealt with many years ago when the BGS seismologists were satisfied it was a natural event associated with movement on a deeper, unassociated fault many miles deeper and distant from the site,” said a spokesman for UKOG.

He also noted that the company is now shifting focus toward alternative energy activities.

Monitoring oil sites for future earthquakes

Oil extraction can offer economic benefits, yet public safety remains a major priority. Scientists recommend that areas targeted for drilling or pumping should be monitored for a stretch of time before projects begin. 

Early seismometers, robust data collection, and transparent reporting can reduce the mystery if quakes do arise. This approach could help communities feel better prepared and help researchers gather key information. 

Many experts see a need for more field data to clarify whether pressure changes from drilling are a likely cause or if these quakes are simply random occurrences that happened around the same time.

The study was published in the Geological Magazine.

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