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
09/10/2015
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