Distributed Acoustic Sensing (DAS)

Distributed Acoustic Sensing (DAS) transforms fiber-optic cables into dense seismic arrays by using coherent laser pulses to measure minuscule strain changes along the fiber caused by passing seismic waves. This technique enables continuous, high-spatial-resolution monitoring over tens of kilometers, making it ideal for both active and passive seismic applications. When applied to existing unused telecommunications infrastructure — so-called dark fiber — DAS provides a cost-effective means to acquire dense seismic data without deploying traditional sensors. However, commercial dark fiber networks often have uncertain coupling conditions and limited access, which can constrain data quality and deployment flexibility. To overcome these limitations, we also propose the installation of dedicated GEUS-owned fiber-optic cables, trenched into the near surface with optimized coupling. This approach offers better control over geometry, deployment environment, and long-term access, enabling high-quality DAS acquisition tailored to specific geophysical objectives.

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