Comment on “The Maximum Possible and the Maximum Expected Earthquake Magnitude for Production‐Induced Earthquakes at the Gas Field in Groningen, The Netherlands” by Gert Zöller and Matthias Holschneider

Abstract

Zoller and Holschneider (2016) propose estimates of the maximum magnitude of induced earthquakes resulting from gas production in the Groningen field in The Netherlands by applying the approach of Zoller and Holschneider (2014) to the earthquake catalog for the Groningen field. We wish neither to make any comment on the analytical approach that the authors propose, nor to comment on their results in this particular application. We do feel obliged to clarify for readers the context of the study by Zoller and Holschneider (2016) in relation to the March 2016 workshop to which they refer. In particular, the sentence in their Introduction stating that “this short note provides the results of those authors” (p. 2917) could be interpreted as implying that their paper presents the results from the workshop. The paper by Zoller and Holschneider (2016) summarizes one of the many inputs that contributed to the workshop, but not the final outcome of the workshop. In response to induced earthquakes in the Groningen gas field, the field operator Nederlandse Aardolie Maatschappij (NAM) is leading an extensive data acquisition and modeling effort to quantify the consequent seismic hazard and risk as a basis for decision making regarding appropriate mitigation measures. All the elements of the study are subject to peer review and the results presented in the open literature (e.g., Bourne et al. , 2014, 2015; Bommer et al. , 2016). Originally, the maximum magnitude M max for the probabilistic seismic‐hazard analysis (PSHA) conducted for the gas field was set at M 6.5, a value obtained from the seismic moment corresponding to the strain energy associated with the entire field compaction at the end of production life being released in a single seismic event (Bourne et al. , 2015). Although the observed strain partitioning factors (i.e., the portion of the total strain that …