Enhancing Long-Term Seismic Analysis of Swiss Geothermal Projects through Waveform Similarity

Induced seismicity remains a significant challenge for the development of deep geothermal energy projects, with continued challenges at both the scientific and operational levels. 

Scientific level: Seismic monitoring at geothermal sites is commonly limited to periods of active operations such as hydraulic stimulation and testing, whereas datasets documenting the seismic response during shut-in and post-operational phases remain scarce. However, larger-magnitude earthquakes have been observed during shut-in phases, and in some cases months later, despite limited information on seismic activity during the active period. As a result, the processes governing delayed, larger-magnitude induced earthquakes remain poorly understood. 

Operational level: During active operations, the spatio-temporal evolution of induced seismicity provides one of the few direct indicators of subsurface processes. Real-time insight into whether seismicity evolves as expected or migrates toward potentially hazardous structures is essential for timely mitigation. Advanced Traffic Light Systems (ATLS) assess seismic hazard and risk based on observed seismic responses and rely on statistical and hydromechanical models to forecast the likelihood of induced events over the following hours to days. The reliability of these forecasts critically depends on the quality of the underlying earthquake catalog. Improved detection and location of small events and more robust magnitude estimates can substantially enhance hazard assessments and operational decision-making. 

To address these challenges, we introduce QuakeMatch (QM), a toolbox that leverages waveform similarity to improve seismic monitoring in both real-time and long-term applications. The workflow employs template matching based on events from a manually revised catalog, followed by refined magnitude estimation, event relocation of assembled events, and statistical analysis. 

We demonstrate the application of QM using the case studies from the Basel and Haute-Sorne deep geothermal projects. The Basel case is currently covered by earthquake catalogs with strongly varying location precision and completeness. A template-matched catalog by Herrmann et al. (2019), covering the period 2006–2019, does not include relocations and has not been updated since its publication. Here, QM is used to build a homogeneous long-term catalog of consistently high-precision earthquake locations that will improve our ability to assess the long-term response of this field over two decades up to the present day. For the Haute-Sorne case, we demonstrate the real-time application of QM, illustrating its potential to better inform advanced induced-seismicity-mitigation procedures (e.g., ATLS) with more reliable, consistent, and sensitive earthquake catalogs. Together, these examples illustrate the potential of combining long-term catalog enhancement with real-time monitoring to support safer and more informed geothermal operations.