Investigating subsea cable sensing for monitoring of marine life, detection of earthquakes and tsunamis with Research and Education network infrastructure

Recent advances in fibre-optic sensing enable subsea telecommunication cables to function as large-scale, distributed environmental sensors. Techniques such as Distributed Acoustic Sensing (DAS), State of Polarisation (SOP), and interferometry transform optical fibres into continuous arrays capable of detecting seismic, acoustic, and environmental signals, offering a complementary, future-proof approach to sparsely deployed subsea instruments. This study, conducted by SURF, the Dutch National Research and Education Network (NREN), assesses the feasibility of leveraging existing and future subsea fibre-optic network infrastructure for scientific sensing within the research ecosystem. The analysis is based on an extensive data collection effort, including 55 semi-structured interviews with international experts across geoscience, marine science, networking, and technology domains, as well as a targeted survey of research institutions, which received 20 responses from 42 invited experts. Results indicate that dry-plant sensing techniques are sufficiently mature for near-term applications, with DAS enabling kilometre-scale seismic and acoustic monitoring, while SOP and interferometry support long-range sensing over thousands of kilometres. Wet-plant approaches, including SMART cables and Fiber Bragg Grating sensors, provide high-precision measurements at extreme depths but remain limited to new cable deployments due to cost and coordination requirements. Strong alignment is observed with current needs in seismology and geophysics, particularly for offshore seismic monitoring and subsurface deformation studies, while applications in oceanography and marine biology remain exploratory. Data volume, standardisation, and real-time processing emerge as key challenges. Research networking organisations play a critical role in enabling scalable, network-centric earth and ocean observation.