Understanding Induced Seismicity Hazard related to Shale Gas Exploration in the UK

This study examines the seismic hazard associated with shale gas exploration in the UK, where such industrial activity is relatively new. We focus on the Preston New Road site in Lancashire, where shale gas exploration occurred in late 2018. We compile, process, and analyse ground motion data from nine seismometers located within 25 km of the site, which detected 57 exploration-related events with local magnitude (ML) range -0.9 to 1.6. We use the data to test a number of pre-existing ground motion prediction equations for suitability to modelling potentially felt events induced by UK shale gas exploration: (1) the Akkar et al. (2014a) equations for European seismicity, (2) the Douglas et al. (2013) equation, developed for induced seismicity in geothermal areas, and (3) the Atkinson (2015) equation, developed for induced seismicity in eastern North America. We find that the Douglas et al. (2013) equation is the most suitable, at least for the considered ground motion intensity measures, although it can over-estimate ground motion variability. To understand if the ground motions differ relative to comparable motions from other types of UK seismicity, we compare the ground motion intensities observed with those recorded during a sequence of earthquakes near Newdigate, Surrey (believed to be natural) and a sequence of events near New Ollerton, Nottinghamshire (induced by coal-mining). We find that – depending on the intensity measure – the intensities are similar to or higher than those of the Newdigate sequence and are similar to or lower than those of the New Ollerton sequence.