Fracking quakes small - report
Independent experts have confirmed the oil and gas drilling practice of fracking caused small earthquakes in England in April and May last year, and have recommended steps to mitigate seismic risk.
Fracking - hydraulic fracturing - involves injecting water, sand and chemicals into rocks to fracture them to release oil and natural gas.
The practice has become controversial around the world, including in this country, as its use has grown sharply in recent years.
In the US it has freed up huge quantities of previously unavailable gas, lowering the price and creating well-paid jobs, but as its use has increased fears have grown about its environmental impact and the seismic risk associated with it.
Last month in New Zealand Parliamentary Commissioner for the Environment Jan Wright announced an official investigation into the practice.
Some countries have banned it, and last week the Christchurch City Council unanimously voted to declare the city a fracking-free zone.
Since 2003, about 30 wells have been fracked in New Zealand.
The report released today in the UK was commissioned by that country's Department of Energy and Climate Change.
Professor Andrew Alpin, from the school of civil engineering and geosciences at Newcastle University, said he welcomed the detailed appraisal, which gave cautious support to continued drilling for a potentially important energy resource.
"We know already that hydraulic fracturing can cause small-scale earthquakes but this study, along with others in the US, shows that they are of insufficient magnitude and extent to cause structural damage or to allow gas or chemicals to leak into much shallower drinking water aquifers," he said.
Quentin Fisher, professor of petroleum geoengineering at Leeds University, said the findings of the independent report were consistent with results from a huge number of shale gas operations in the US, which indicated hydraulic fracturing was safe and was highly unlikely to result in seismic activity that would cause structural damage in the local area.
Measures recommended by the report seemed sensible in the short term but should be constantly reviewed as more data became available to ensure they did not result in over-the-top regulations.
Professor Stuart Haszeldine, from the school of geosciences at Edinburgh University, said the report started to put UK shale gas exploration on a more secure base.
Installing much better local monitoring was the best way forward, and should have been done at the beginning.