One area of concern for some people around fracking is the idea that this process causes seismic activity. In reality, recorded incidents of seismic activity associated with this process are extremely rare. There are naturally occurring seismic movements documented on a daily basis across Britain.
Natural seismicity in the UK is low by world standards. On average, the UK experiences seismicity of magnitude 5 (felt by everyone nearby) every 20 years and of magnitude 4 (felt by many people) every three to four years.
The British Geological Survey (BGS) publishes a record of all earthquakes around the British Isles in the past 50 days. Based on a search conducted on 14 August 2013, there were 18 recorded earthquakes in the previous 50 days, including two with a magnitude of 2.8 and one in Doncaster measuring 1.9.
According to the BGS, an earthquake is only considered to be "significant" should it measure above 4 and an earthquake measuring below 3 is generally not felt at the surface, let alone the cause of any damage.
Induced seismicity, unlike natural seismicity, is caused by human activities such as mining, deep quarrying, hydrogeological extraction or fluid disposal and activities associated with non-conventional hydrocarbon extraction.
According to the Royal Society and Royal Academy of Engineering, BGS records indicate that coal mining-related seismicity is generally of smaller magnitude than natural seismicity and no larger than magnitude 4.
According to the Royal Society, the Royal Academy of Engineering and Durham University, seismicity induced by hydraulic fracturing is likely to be of even smaller magnitude than mining.
In any event, there are stringent guidelines to ensure seismic monitoring takes place before during and after any activity.