Fracking does not cause earthquakes that can be felt on the surface in the vast majority of cases, claims new research.
A study of hundreds of thousands of hydraulic fracturing operations that use a controversial method of extracting shale gas trapped in underground rocks found just three examples where the process has caused tremors on the surface.
The research, led by Durham University, also found the size and number of detected earthquakes caused by fracking was low compared to those caused by other manmade triggers such as mining, geothermal activity or reservoir water storage.
‘In almost all cases, the seismic events caused by hydraulic fracturing have been undetectable other than by geoscientists,’ said Prof Richard Davies from Durham Energy Institute.
‘So we have concluded that hydraulic fracturing is not a significant mechanism for inducing felt earthquakes. It is extremely unlikely that any of us will ever be able to feel an earthquake caused by fracking.’
He added this possibility could not be ruled completely but that there were ways to mitigate against it, particularly by avoiding critically stressed faults that already near breaking point.
Previous research, including the study that found tremors felt in Lancashire in 2011 were likely caused by nearby fracking operations, has reached similar conclusions about the relationship between hydraulic fracturing and earthquakes.
The process, which is widely used in the US and has been trialled in the UK, involves pumping large amounts of water and chemicals into the ground under pressure to fracture rocks and release the gas trapped inside them.
The UK government last year introduced guidelines for fracking operations with the aim of preventing dangerous seismic activity, after it lifted a temporary ban on the process introduced following the Lancashire tremors.
This included a traffic light system requiring fracking companies to pause and review their operations if seismic activity reaches magnitude 0.5 by conducting constant seismic monitoring before, during and after the operation.
The Durham study examined all human-induced earthquakes since 1929. Of the three fracking-related quakes felt at the surface, the largest, detected in Canada in 2011, had a magnitude of only 3.8. The Lancashire tremor had a magnitude of 2.3.
Prof Davies told The Engineer the study was funded by the university without any money from industry or other public bodies, but that the university did carry out other industry-funded geoscience research.
Other criticisms of fracking include its potential to contaminate ground water supplies with chemicals or gas, as well as the fact that it increases supplies of fossil fuels at a time when the world should be switching to low-carbon energy sources.
New UK regulations mean companies are required to disclose the chemicals they use in their fracking fluid and that only substances not deemed to be hazardous to the water supply can be licensed for use.
Well inspections by third-party advisers and government officials will also be mandatory in an attempt to ensure the integrity of wells and prevent the contamination of the ground or water supply.