Estimating the maximum magnitude of induced earthquakes in the Groningen gas field, the Netherlands; discussion

In their "Estimating the maximum magnitude of induced earthquakes in the Groningen gas field, the Netherlands," Bommer, van Elk, and Zoback (BvEZ) present good reasons to revise the 2022 expert-panel assessment of the maximum possible earthquake magnitude (M (sub max) ) in the Groningen gas field, but their timing (August 2024) and authorship are remarkable. Here, it is argued that: (1) induced M (sub max) arises from a changing seismic source, (2) effective safety communication requires clarification of the practical meaning of "logic tree", "expert weight", and "possible" versus "expected" (3) multivariate sensitivity analysis is needed to appreciate the implications of M (sub max) , for example, surface (vibratory) ground movements, (4) independent peer review may be useful but too much asked, and that (5) possible conservatism in M (sub max) assessment may be due to (costly) precautionary reasoning under uncertainty. The importance of balanced multiparty risk communication is emphasized. Concluding remarks are about institutional responsibilities for (apparently) insufficient M (sub max) assessment in 2022, the implications of BvEZ's current re-evaluation for further building reinforcement and restoration policies for Groningen, and the desirability of reviving the expert assessment process on M (sub max) , to validate BvEZ's main proposal that, for Groningen, 3.6 < or = M (sub max) < or = 4.1. After the field's recent closure, ever observable M (sub max) will probably never exceed the historical earthquake magnitude of 3.6 near Huizinge in 2012.