Recent geological research indicates that over 100 minor earthquakes in the south of England may have been triggered by oil extraction activities. This new analysis contrasts with earlier findings that dismissed a connection.
The earthquakes, which measured between 1.34 and 3.18 on the Richter scale, occurred near Newdigate in Surrey between 2018 and 2019, causing noticeable shaking for residents.
Initial speculation suggested a link to oil extraction operations, particularly at the Horse Hill drilling site operated by UK Oil & Gas. However, earlier studies by the British Geological Survey asserted the seismic events were coincidental and of natural origin.
Researchers Matthew Fox and Philip Meredith from University College London revisited this issue with advanced geological data and simulations. Their findings indicate that the earthquakes correspond closely with the timing and location of oil extraction activities.
Their simulations utilized over a million scenarios to analyze how oil extraction affects geological pressure, revealing that pressure changes can indeed lead to rock movement and subsequent earthquakes. Fox noted that discrepancies in timing between the earthquakes and oil extraction activities can now be explained through updated geological understanding.
In porous rock formations like Portland stone, pressure changes can trigger earthquakes almost immediately, while denser formations such as Kimmeridge Clay may experience delays as pressure accumulates.
Fox remarked, “The correlation between oil extraction and seismicity is quite strong, which suggests a possible link between the two.”
While he acknowledges that a coincidental relationship cannot be completely ruled out, he believes it is now less probable than previously thought. Further statistical analysis is expected to clarify the likelihood of coincidence.
UK Oil & Gas controlled operations at the Horse Hill site until October last year when they ceased after planning permissions were revoked following legal challenges from environmental campaigners.
A spokesperson for the company previously asserted that the earthquakes were conclusively shown to be unrelated to their activities, attributing them to natural geological movements at greater depths.
However, Stuart Haszeldine from the University of Edinburgh, who has conducted separate research, expressed strong belief in a connection between oil extraction at Horse Hill and the seismic events, stating, “There was a clear linkage of earthquake timing and operational activities to produce oil and gas from the Horse Hill site.”
