Overview of the Swiss Seismological Service’s Efforts to Monitor the July 2025 Test-Stimulation in Haute-Sorne, Switzerland

Abstract

In Switzerland, the subsurface is under the sovereignty of the 26 different cantons, with cantonal authorities in charge of the permitting and regulatory oversight of industrial projects targeting the subsurface. The GEOBEST program ensures that the Swiss Seismological Service can provide seismological expertise and baseline seismic monitoring services to the cantons at no cost, and independently of the operators of geothermal projects. For the EGS pilot project in Haute-Sorne, the republic and canton of Jura receives the support of the Swiss Seismological Service with seismological counseling and risk governance recommendations, as well as the operation of a dedicated seismic network. This seismic network completed in February 2024 consists of seven stations (broadband and strong motion), and was designed to ensure a magnitude of completeness of at least MLhc0.5. The test-stimulation carried out in July 2025 saw 430m³ of water injected at nearly 4km depth with injection rates up to 80L/min. During this period, the Swiss Seismological Service provided 24/7 automatic alarms in a 4 km radius with manual revision within the hour. These alarms fed the magnitude-based traffic light system operated by Geo-Energie Jura, the operator of the Haute-Sorne project.