Fracking expansion could cause more earthquakes in UK

An earthquake expert warns over the dangers of fracking that could critically stress the fault lines in UK, leading to increase in seismic activities. A new analysis shows that 21 percent of about 1,800 seismic events with 1.5 magnitude or above was triggered by human activities.

The report, published in the journal Marine and Petroleum Geology, shows that at least three earthquakes strike the UK each year because of human activity, with two caused by fracking exploration since 2011. The analysis is the first in the world to set a national baseline to detect any rise in earthquakes following an expansion of shale gas exploration in the future.

Lead researcher Richard Davies, a professor at the Newcastle University, said that the largest earthquake that could be triggered by fracking or coal mining can cause anxiety for local people and damage to fragile structures. In fact, there are many seismic activities due to collapsing mines or fracking but are commonly small and unnoticed by people.

“Historically, fracking-related earthquakes have been small, but the UK is criss-crossed by faults – some of which may be critically stressed – and if triggered these could result in earthquakes that people can feel,” Davies said. Fracking is the process of drilling down into the ground to pump liquid at high pressure to fracture rock and to release the gas inside.

The researchers reviewed 8,000 recorded earthquakes in the UK between 1970 and 2012. They found that since 1970, about one in five earthquakes in the UK have been caused by human activities, however, the real number may still be higher.

One of the recorded man-made earthquakes felt by people was the collapsing lead mines in Derbyshire in UK in 1750s.

Due to lack of information, scientists could not classify many earthquakes if it’s natural or man-made. But if half of the unclassified tremors were man-made, the average number of tremors rises from three to 12 every year.

Davies and his team used a past record as the basis of theorising the effect of human activities to trigger earthquakes. The team discovered that since 1980s, the number of earthquakes has fallen by 95 percent when the UK’s deep coal mines collapsed.

Despite the decline in the seismic activities in recent decades, the UK government aims to go "all out for shale" to push energy security and the economy through shale gas exploration. But experts fear that the activity may again prompt more earthquakes and other environmental impacts.

"Earthquakes triggered or induced by humans are not a new concept for us here in the UK, but earthquakes related to fracking are,” Davies said. In 2011, a gas exploration in Lancashire caused a 2.3 magnitude earthquake, followed by a second earthquake after two months.

The officials immediately suspended fracking until new policies were provided to limit the risk of earthquakes. But some experts say that man-made earthquakes in shale-bearing rocks in the UK are unlikely to reach magnitude 3 that rarely cause any damage.

"As recognised by this research, there are no documented cases of shale gas operations causing subsidence or earthquakes which have caused damage at the surface,” a spokesman for the Department of Energy and Climate Change said. The government have robust controls in place to mitigate seismic risks and in the unlikely event that any operations were to pose a risk, he added, “we have the powers required to close them down.”

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