Marine Distributed Acoustic Sensing (DAS) for Detection of Submarine CO₂ Bubble Emissions: Insights from a Shallow-Water Volcanic Setting at Panarea (Italy)

Fibre-optic sensing technologies are rapidly transforming geophysical monitoring by enabling spatially dense, temporally continuous observations of seismic and acoustic wavefields in environments that are difficult to instrument with conventional sensors. In marine settings, Distributed Acoustic Sensing (DAS) applied to seabed fibre-optic cables offers new opportunities for low-impact monitoring of fluid and gas migration processes, which are fundamental both to volcanic–hydrothermal systems and to emerging offshore carbon capture and storage (CCS) applications.

In this study, we investigate the feasibility of marine DAS for detecting natural and artificial CO₂ bubble emissions in a shallow-water volcanic environment offshore Panarea (Aeolian Islands, Italy). Panarea hosts the OGS NatLab Italy, part of ECCSEL-ERIC, thanks to its active submarine degassing associated with a hydrothermal system and therefore represents a natural laboratory and an analogue site for potential subseabed CO₂ leakage scenarios. A 1.1-km-long armored fibre-optic cable was deployed on the seabed and interrogated using two different DAS systems, providing continuous passive acoustic and seismic recordings. To support signal identification and interpretation, the DAS data were complemented by controlled gas releases from scuba tanks, by a High Resolution Seismic (boomer) survey and side-scan sonar imaging, to characterize seabed morphology and shallow subsurface structures along the cable route.

The DAS recordings revealed acoustic signatures associated with both natural CO₂ bubble emissions and controlled artificial releases. Bubble-related signals were detected as localized, temporally variable acoustic responses along the fibre, demonstrating the sensitivity of DAS to gas-driven processes at the seabed. The integration of passive DAS monitoring with active seismic imaging techniques enabled a more robust interpretation of observed signals and seabed processes.

From an Earth sciences perspective, these results demonstrate that marine DAS can serve as a low-impact, spatially continuous monitoring tool for submarine volcanic and hydrothermal systems, complementing traditional geochemical sampling and visual observations and offering new insights into the temporal variability of degassing activity. Beyond natural systems, the demonstrated capability of DAS to detect bubble-related acoustic signals has direct implications for offshore CCS, where early detection of CO₂ leakage is critical for storage integrity and environmental safety.

Overall, this field-scale experiment highlights the potential of fibre-optic sensing to address key challenges in marine monitoring, and underscores the value of integrated approaches for studying fluid and gas migration processes.

Acknowledgements:

• ECCSELLENT project (“Development of ECCSEL - R.I. ItaLian facilities: usEr access, services and loNg-Term sustainability”)
• ITINERIS - Italian Integrated Environmental Research Infrastructures System - Next Generation EU Mission 4, Component 2 - CUP B53C22002150006 - Project IR0000032
• Panarea NatLab Italy: https://eccsel.eu/catalogue/facility/?id=124
• ECCSEL: https://eccsel.eu/

 

References:

• Detection of CO2 emissions from Panarea seabed with Distributed Acoustic Sensing (DAS): a preliminary investigation. Meneghini et al. OGS report (2025).
• Marine Fiber-Optic Distributed Acoustic Sensing (DAS) for Monitoring Natural CO₂ Emissions: A Case Study from Panarea (Aeolian Islands, Italy). Bellezza et al. Upon submission to Applied Sciences (2026).