On September 9, 2015, the Marine and Petroleum Geology Academic Journal published a study entitled “Anthropogenic earthquakes in the UK: A national baseline prior to shale exploitation.” The study establishes a baseline number of natural and anthropogenic onshore seismic activities in the UK from 1970 to 2012.
The purpose of this baseline is to provide a sufficient data base to determine the impacts of future seismic events in the UK as well as identifying if using hydraulic fracturing has become a major risk factor for seismic activity. According to the study, coal mining was the largest “anthropogenic” activity to trigger seismic events in the UK over the past century. Researchers observed that since coal mining activity has rapidly declined in the past 25 years, there has been a general decrease in the numbers of seismic events.
Of 1769 onshore seismic events of M1.5 or lower, the researchers attributed at least 21% of onshore seismic events to “anthropogenic” activities and at least 40% of those to natural causes while about 39% have an undetermined origin. As stated in the study, “[a]ll but two anthropogenic events with [M1.5 or lower] between 1999 and 2012 have been caused by coal mining and this remains the current dominant cause of anthropogenic seismicity in the UK.”
Researchers, however, concluded that recent shale gas operations may increase the number and severity of seismic events. They identified the Bowland-Hodder shale play as being a seismically active area near critically stressed faults.
Written by Chloe Marie - Research Fellow