An Adapted Båth’s Law Framework for Assessing Trailing Seismicity in Dutch Gas Fields
B.B.R. Schmal (TU Delft - Civil Engineering & Geosciences)
A.G. Muntendam-Bos – Mentor (TU Delft - Civil Engineering & Geosciences)
D.F. Naranjo Hernandez – Mentor (TU Delft - Civil Engineering & Geosciences)
A.M.H. Pluymakers – Graduation committee member (TU Delft - Civil Engineering & Geosciences)
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Abstract
Induced seismicity related to gas production remains an important scientific and societal issue in the Netherlands, especially because earthquakes may continue after production has stopped. This post-production activity, known as trailing seismicity, creates uncertainty in seismic hazard assessment, since the largest earthquake does not necessarily occur during the production phase. This thesis investigates whether the largest observed trailing earthquakes in Dutch gas fields, with specific focus on the 2025 Zeerijp earthquake in Groningen, can be justified using an adapted framework of Ryan Schultz combined with Gutenberg-Richter magnitude-frequency statistics.
Earthquake data from the Koninklijk Nederlands Meteorologisch Instituut (KNMI) catalogue were divided into production and post-production events for selected Dutch gas fields. The main parameters used in the analysis were the magnitude of completeness, the number of production and trailing earthquakes, the production-seismicity ratio, the Gutenberg-Richter b-value, and the maximum magnitude parameter. Groningen was used as a control case because of its larger earthquake catalogue, while Annerveen, Eleveld and Roswinkel were analysed as smaller gas field examples. A Monte Carlo approach and logic-tree structure were used to include uncertainty in the input parameters and to estimate distributions of the largest expected trailing magnitude.
The results show that the observed Zeerijp earthquake with magnitude 3.4 falls within the predicted Groningen magnitude distribution. For the smaller gas fields, their observed largest trailing magnitudes are justified as well; however, uncertainty increases. Overall, the adapted framework can justify the largest observed trailing events within the selected Dutch gas fields, but the reliability of the prediction depends on the assumed b-value, completeness magnitude, seismicity ratio and maximum-magnitude constraint. Therefore, the method is useful as a probabilistic tool but should be interpreted together with field-specific geological and catalogue uncertainties.