Fiber optic cables (DAS) for seismic event detection – An underground case study

Distributed Acoustic Sensing (DAS), leveraging existing fiber optic infrastructure, represents a groundbreaking advancement in seismic monitoring. By converting telecommunication cables into dense arrays of virtual sensors, DAS enables continuous spatial coverage and enhanced sensitivity to seismic waves in remote or logistically constrained environments. This capability positions DAS as a complementary or alternative tool to traditional seismic networks, offering cost-effective, low-maintenance solutions for geophysical research and hazard monitoring.

This study focuses on the Premise-2 experiment, conducted at the Low-Noise Underground Laboratory (https://www.lsbb.eu/) in Rustrel, France, a site renowned for its low seismic noise. The experiment integrates active and passive seismic acquisitions, capturing both ambient noise and controlled seismic signals to assess DAS’s ability to detect and characterize events. Multiple fiber optic cable types and installation methods (laid on the ground, with sand bags, buried, or structurally attached) are evaluated to determine their impact on signal sensitivity, spatial resolution, and measurement robustness.

This study provides critical insights into optimal DAS deployment configurations for seismological applications while highlighting the challenges posed by large-scale data acquisition. The research underscores the need for advanced algorithms and specific workflows to fully exploit DAS’s potential. To characterized the events, we have used a workflow using automatic P and S arrival phases. We filtered these arrivals with an associator to select only detections that could be linked to an event. Then we tried different location algorithms to get a complete workflow from the acquisition to the location of the events.