KEM-11b Review for improving the KNMI datasets and catalogue for the Groningen gas field

The objective of this research question, being a follow up of the KEM-11a study in 2018, is to re-evaluate the quality of and correct or partially reprocess seismological data recorded in the area of the Groningen gas field used for calibrating GMPE’s, which are part of the Groningen seismic hazard and risk assessment model.

In 2019, a series of studies were carried out to understand the in 2018 observed flaws in the Groningen seismological data recordings. These reports and a summarizing report were published mid 2019 by the State supervision of Mines. Several KEM projects also indicated that quality and coverage outside the Groningen area (completeness) need to be improved. Recommendations have been made to improve.

The main objective is to obtain a more complete understanding of what a state-of-the-art seismological recording network and event catalogue comprises with respect to building reliable and consistent GMPEs. Based on these findings, an assessment needs to be made of an the ideal and the current seismological networks as well as the seismic event catalogue in Groningen and a recommendation on necessary and feasible methods and means to improve on the current setup.

FULL RESEARCH REQUEST
 

The KEM-11b (Phase 2A) research project is commissioned to Norsar and GfZ and started in 2020. The project started in medio 2019 and finished September 2020.

PROJECT FINAL REPORT and ANNEXES

The final report has two parts. In the first part concerns the assessment of the seismic network and the data collection methods for the purpose of computing Ground Motion Prediction Equations(GMPE) for the Groningen field. It describes a state-of-the-art system tailored towards the Groningen field case. The recommendations include seismic network design, instrumentation and deployment requirements, data collection procedures and quality assurance. Many of these recommendations can also be regarded as relevant to alternative induced seismicity monitoring applications, with the Groningen specific considerations highlighted with in the text.

In the second part previous reports on the accelerometer network records are reviewed and assessed. It is concluded that all sensors and settings of the seismological networks in Groningen should now function correctly and that scheduled quality control procedures in order to duly identify any potential future failures is recommended. Further, the instrumentation, waveform data and meta data, which were used as the basis for the GMMV6, are assessed and evaluated against the recommendations derived for a state-of-the-art system. Five issues to take care of were identified from the assessment of the status of the Groningen accelerometer network.

The final chapter discusses potential improvements to the current network and data collection, with the following main topics: inclusion of recent earthquakes with magnitudes smaller than ML 2.5, inclusion of vertical component observations and deploying observations of existing shallow and new deeper boreholes.

This report contribute to highlighting the high quality monitoring programme ongoing within the Groningen field especially after the installation of the G-network and its contribution to the development of the ground motion model. And it provides very relevant information to design and install other seismological networks around mining activities in The Netherlands.

The final evaluation of the project by KEM scientific experts can be found here.
RESEARCH PROJECT EVALUATION
The quality of the investigation is judged to be excellent and the results, discussed in more detail below, are important for a number of stakeholders.
The final report delivers a wide range of important results that should not be undervalued because they are overall quite technical, and detail-oriented in nature. For instance, the report makes wide range of suggestions for changes to procedures, and these are highly valuable results that will influence in a multitude of ways operational and data analysis procedure and ultimately increase the quality of the Groningen seismic data. KNMI has already started to implement some of these procedures and hopefully more can be considered in the medium term. The report also provides interesting suggestions to better calibrate the GMM component model of the seismic and hazard risk model train. The provided results are considered excellent and useful for regulators, KNMI and the public as an independent point of reference for quality assurance of current and future developments of the Groningen seismic monitoring system.

The research results on the Groningen seismological network (this project KEM-11b), follow up by KNMI and on the seismological catalogue (earlier project KEM-11a) have been presented and discussed in a KEM-DeepNL colloquium May 31, 2022. The presentations can be viewed using these links: KEM-11a presentation, KEM-11b presentation and KNMI-11 presentation. KNMI also issued in 2023 a final report on the quality assurance of the KNMI data. KNMI also issued in 2023 a final report on the quality assurance of the KNMI data.