Published January 2025 | Published
Journal Article Open

Bursts of Fast Propagating Swarms of Induced Earthquakes at the Groningen Gas Field

  • 1. ROR icon California Institute of Technology
  • 2. ROR icon Shell (Netherlands)
  • 3. Nederlandse Aardolie Maatschappij B.V.

Abstract

Gas extraction from the Groningen gas reservoir, located in the northeastern Netherlands, has led to a drop in pressure and drove compaction and induced seismicity. Stress‐based models have shown success in forecasting induced seismicity in this particular context and elsewhere, but they generally assume that earthquake clustering is negligible. To assess earthquake clustering at Groningen, we generate an enhanced seismicity catalog using a deep‐learning‐based workflow. We identify and locate 1369 events between 2015 and 2022, including 660 newly detected events not previously identified by the standard catalog from the Royal Netherlands Meteorological Institute. Using the nearest‐neighbor distance approach, we find that 72% of events are background independent events, whereas the remaining 28% belong to clusters. The 55% of the clustered events are swarm‐like, whereas the rest are aftershock‐like. Among the swarms include five newly identified sequences propagating at high velocities between 3 and 50 km/day along directions that do not follow mapped faults or existing structures and frequently exhibit a sharp turn in the middle of the sequence. The swarms occurred around the time of the maximum compaction rate between November 2016 and May 2017 in the Zechstein layer, above the anhydrite caprock, and well‐above the directly induced earthquakes that occur within the reservoir and caprock. We suggest that these swarms are related to the aseismic deformation within the salt formation rather than fluids. This study suggests that the propagating swarms do not always signify fluid migration.

Copyright and License

© 2024 Seismological Society of America.

Acknowledgement

This research is supported by the National Science Foundation (NSF)/Industry‐University Collaborative Research Center “Geomechanics and Mitigation of Geohazards” (NSF Award Number 1822214), and the Enhancement Project GMG‐3 funded by Nederlandse Aardolie Maatschappij (NAM). The authors gratefully acknowledge data and support from Shell Global Solutions and thank Editor‐in‐Chief Allison Bent, the associate editor, and two anonymous reviewers for insightful and detailed comments, which greatly improved the quality of the article.

Data Availability

Raw seismic waveforms were accessed through the Observatories and Research Facilities for European Seismology (ORFEUS) International Federation of Digital Seismograph Networks (FDSN) client via a Python script using the package ObsPy (https://docs.obspy.org/Beyreuther et al., 2010). The 3D seismic velocity and faults map were provided to us by Shell Global Solutions International B.V. Computer programs used to generate the enhanced seismicity catalog are previously published and can be found in the following references: seismic phase detection software PhaseNet (https://github.com/AI4EPS/PhaseNetZhu and Beroza, 2019), seismic phase association software GaMMA (https://github.com/AI4EPS/GaMMAZhu et al., 2022), hypocenter inversion software HypoSVI (https://github.com/Ulvetanna/HypoSVISmith et al., 2021). The seismicity catalog from the Royal Netherland Meteorological Survey (KNMI) is available online at www.knmi.nl. MATLAB version 2020a was used to analyze data and prepare figures. The enhanced seismicity catalog generated in this study along with the picks of arrival times can be found in the supplemental material. Codes used for data analysis and figure generation are made available online through CaltechDATA repository at https://data.caltech.edu/records/emasj-np244. All websites were last accessed in March 2024. The supplemental material for this article includes supplemental figures, enhanced high‐resolution seismicity catalog (data S1), and the associated picks of P‐ and S‐wave arrival times (data S2).

 

Supplemental Material

Supplementary data:

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Additional details

Created:
January 7, 2025
Modified:
January 9, 2025