Gas drilling firm Cuadrilla Resources has confirmed it is highly probable that its attempts to extract shale gas caused the tremors felt in Blackpool earlier this year.
In a report examining the seismic activity near Cuadrilla’s Lancashire site, experts conclude that the firm’s hydraulic fracturing operations were the likely cause of the small earthquakes.
Hydraulic fracturing, or “fracking”, involves pumping millions of gallons of pressurised water, sand and chemicals into fractures in shale rock to release natural gas trapped in it.
According to the report, the pressure of the water released during fracking combined with the unusual geology of the area probably caused the tremors in April and May which measured 2.3 and 1.5 on the Richter scale.
However, the report concluded it was very unlikely that fracking would trigger similar seismic activities at other drilling sites in the UK and that even if it did tremors would not exceed 3 on the Richter scale, posing no threat to safety on the surface.
Despite these conclusions, the authors include in their report proposals for an early warning system that could prevent any future seismic events exceeding safe limits. Suggestions include halting fracking activities if a tremor of 1.7 is felt and removing water from the drilling well to reduce pressure.
Mark Miller, chief executive of Cuadrilla, welcomed the report saying the company accepted all of its findings.
“We are ready to put in place the early detection system that has been proposed in the report so that we can provide additional confidence and security to the local community,” he said.
Cuadrilla’s fracking operation at the Preese Hill site is the only one of its kind in the UK and it has remained closed since the second tremor in May. DECC, advised by the British Geological Survey, independent experts, and the other key regulators - the HSE and the Environment Agency - are currently examining the report before deciding whether Cuadrilla can resume drilling.
A DECC spokesman confirmed: “The implications of this report will be reviewed very carefully before any decision on the resumption of these hydraulic fracture operations is made.”
Although used widely in the US, fracking remains a controversial technique with critics arguing it pollutes groundwater and effects the environment. The report into Cuadrilla’s activities at Preese Hill, however, concludes that groundwater aquifiers, which are located 300m below the surface, are protected from the fracking water by two layers of impermeable rock.
The report has failed to convince critics of the technology, however, with Friends of the Earth arguing that there should be no more fracking in Britain “until the health and environmental impacts are fully understood”.
