Gas 'Fracking' To Restart Amid Quake Fears

A controversial gas drilling operation that triggered earthquakes in Britain is set to be restarted but with tighter controls on the process.

The company involved has accepted stringent recommendations from Government-commissioned experts who say hydraulic fracturing - known as 'fracking' - should be allowed to continue at the Preese Hall well in Lancashire.

One of the provisos is that even a tremor too small to be noticed above ground should result in an immediate shutdown, with compulsory remedial action before a resumption of drilling.

The independent report also calls for careful monitoring of the site using arrays of seismic sensors, and steps to ensure excess pressure cannot build up beneath the ground.

Fracking involves injecting high pressure water, sand and chemicals into shale rock to release trapped gas and has made exploitation of previously uneconomical reserves feasible.

Well operator Cuadrilla Resources estimates that the Bowland Basin prospect site in Lancashire contains as much as 200trn cubic feet of gas.

Even if only a fraction of this can be extracted, it still represents a very significant energy resource.

On April 1 and May 27 last year, two small earthquakes - of magnitude 2.3 and 1.5, respectively - occurred in the Blackpool area.

No damage was caused, although a number of people called the police to report shaking.

After the second tremor was linked to fracking, operation of the Cuadrilla exploration well was halted.

Later independent experts appointed by the firm concluded that both tremors were triggered by fracking and proposed a "traffic light" early warning system.

The events led to public protest, with one group scaling a test drilling rig at Hesketh Bank in Lancashire.

In the US, similar protests have become increasingly vocal over environmental concerns and claims of groundwater contamination.

The new report, commissioned by the Department of Energy and Climate Change (DECC), confirmed that the earthquakes were caused by fracking taking place in a geologically stressed and vulnerable area.

The report's authors said further fracking-induced earthquakes were possible but unlikely to cause structural damage.

The report said: "Such an event would be strongly felt by people within a few kilometres from the epicentre and could cause some alarm."

In their "traffic light" plan, Cuadrilla's consultants suggested a threshold of magnitude 1.7 - well short of structural damage levels - at which point fracking operations should stop.

But the DECC-appointed experts thought this was too high and proposed a much lower threshold of magnitude 0.5. A tremor this small is unlikely even to be noticed by anyone within its range.

A six-week consultation period will now follow before any final decision is taken on shale gas fracking.

DECC's chief scientific advisor David MacKay said: "If shale gas is to be part of the UK's energy mix we need to have a good understanding of its potential environmental impacts and what can be done to mitigate those impacts.

"This comprehensive independent review of Cuadrilla's evidence suggests a set of robust measures to make sure future seismic risks are minimised - not just at this location but at any other potential sites across the UK."