Estimating the Maximum Magnitude of Induced Earthquakes in the Groningen Gas Field, the Netherlands

ABSTRACT Gas production in the Groningen field in the northern Netherlands began in 1963. Since 1991, many production-induced earthquakes have occurred—the largest reaching magnitude M 3.5 in 2012. In October 2023, the Dutch government closed the field—a decision that was justified by the potential threat of larger earthquakes occurring with continued gas extraction. This outcome highlights how the estimation of maximum magnitude for induced earthquakes can have important implications for risk perception by regulators and the public. Thus, the estimation of maximum magnitude for induced earthquakes that are not physically realizable can lead to unwarranted conservatism. Over almost three decades, considerable effort has been invested by several researchers to estimate the maximum magnitude of induced earthquakes in Groningen. These efforts culminated in international workshops focusing exclusively on this question in 2016 and 2022. The purpose of these workshops was to inform the decision-making of an expert panel charged with formulating a logic tree for the maximum magnitude of Groningen earthquakes. We argue that the evaluation of the final distribution of maximum magnitudes is overly conservative in terms of the largest events induced in the reservoir and, most importantly, the likelihood of triggering even larger tectonic earthquakes outside the gas-producing reservoir. Given the serious and far-reaching consequences of maximum magnitude estimates, we reconsider the approach of these assessments to draw lessons that may be critical for future energy-related projects associated with induced seismicity.