Realistic microearthquake magnitudes and locations from surface monitoring of hydrofacturing at preston new road, UK

Traffic light systems are often used to reduce the probability of damaging seismicity during anthropogenic activities such as industrial mining, geothermal energy and hydraulic fracturing operations. Under such system operations are continued ("green"), amended ("amber") or stopped ("red") based on the local event magnitude. Accessing accurate microseismic magnitudes is challenging due to unquantified uncertainties, which cannot be neglected in TLS because they can exceed a whole magnitude unit - large enough to make a difference between a continuation as planned ("green") and an immediate stop ("red") of operations. A way to account for these uncertainties in the choice of TLS thresholds was demonstrated such that an operator or regulator can choose between a system which minimizes either the risk of future larger magnitude events or the risk of incorrectly halting operations (C. Roy, pers. comm., 2020). The purpose of this study is to assess the impact of these two different TLS strategies on decisionmaking for induced seismicity at Preston New Road, UK.