Operations at the Preston New Road site are continuing following the series of minor seismic events, including three that have exceeded the seismic magnitude 0.5ML limit for caution. This threshold is set at a level far below what could be perceptible at the surface and following any event that exceeds the threshold, the operator is required to immediately pause, reduce pressure and monitor for any further events.

During these pauses, the OGA compares the location, magnitude and ground motion of these minor seismic events to the operator’s approved Hydraulic Fracture Plan (HFP).  To date, the OGA has been satisfied that these have events have all been in line with the geological understanding set out in the HFP and that the risk of induced seismicity is being appropriately managed.

OGA Director of Regulation, Tom Wheeler, said: 
“We knew that very low level seismic events deep underground were entirely possible during fracturing operations and this is what has been happening recently at Preston New Road.  There are several thousand minor seismic events like these occurring naturally in the UK every year and can only be detected at the surface with specialist equipment.

“We are taking a cautious approach and have strict controls in place so that even this low level seismic activity results in a pause in operations to allow us to review the event and ensure that the operator’s approved plan is still valid.”

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