Baseline seismic monitoring is crucial for the safe and sustainable development of most geotechnical projects. Before commencing such a project, seismic monitoring can contribute to a better understanding of the local natural seismic activity. However, its primary role emerges during the construction and operational phases of a project when it aims to swiftly and accurately detect earthquakes near the project site. In this way, it helps the involved experts to analyse the development of the reservoir (role of the operator with its own network) and to distinguish between project-related seismic events and those of natural origin (role of the SED).

The SED operates a baseline seismic monitoring network, independently of the operator, Geo-Energie Suisse Jura SA (GEJ), for the Canton of Jura. This network is embedded in the SED’s national seismic network and its analysis and real-time alerting system. The key objective is to provide the canton, the public and media with timely, independent, and authoritative information. The network will drive a traffic light system that is part of the oversight and risk mitigation plan. The network will be able to detect all earthquakes above a magnitude 0.5 and locate them with a precision of 500 meters.

The SED started to install additional seismic monitoring stations in the Haute-Sorne region in November 2022 to increase the density of the national network, which already included a number of stations in the region. The baseline monitoring network was put into operation in July 2023 and completed in early 2024 with five broadband stations. The network is complemented by strong-motion and other seismic stations in the wider surrounding of the project site available to the SED in real-time. These include four stations operated for the Mont Terri rock laboratory as well as stations from the French and German national networks. In addition, the SED has real-time access to six broadband stations managed by GEJ and includes them in its monitoring system.

GES will further operate dedicated monitoring equipment within deep boreholes to characterize the development of the geothermal reservoir during the hydraulic stimulations. Even though this data is less relevant for operational safety, SED will include it in its monitoring system where possible. The SED data is openly available and also shared in real-time with GEJ. This bilateral data exchange improves seismic monitoring on both sides and ensures that relevant data is available to all stakeholders to support operational decisions.