Marine Fiber-Optic Distributed Acoustic Sensing (DAS) for Monitoring Natural CO2 Emissions: A Case Study from Panarea (Aeolian Islands, Italy)

Featured Application: This study highlights marine Distributed Acoustic Sensing (DAS) as a low-impact, spatially continuous technology for monitoring sub-seabed fluid and gas migration. In volcanic and hydrothermal settings, DAS enables long-term observation of degassing processes, providing high temporal resolution that complements geochemical and visual surveys. Furthermore, its sensitivity to bubble-related acoustic signals makes it a viable tool for offshore Carbon Capture and Storage (CCS), ensuring early detection of potential leaks. DAS offers a cost-effective, scalable, and non-invasive solution for environmental surveillance in both natural and engineered submarine systems. Submarine gas emissions represent a key expression of fluid migration processes in volcanic and hydrothermal marine environments and provide valuable analogues for monitoring strategies relevant to sub-seabed carbon storage. This study investigates the feasibility of using marine Distributed Acoustic Sensing (DAS) to detect natural CO2 bubble emissions in a shallow-water setting offshore Panarea (Aeolian Islands, Italy). A 1.1 km armored fiber-optic cable was deployed on the seabed and interrogated using two different DAS systems to acquire continuous passive acoustic data. The DAS recordings were complemented by controlled gas releases from scuba tanks to provide reference signals, as well as by independent high-resolution boomer seismic survey and side-scan sonar imaging to characterize the shallow subsurface and seabed morphology. The results show that DAS is sensitive to acoustic signals associated with both artificial and natural bubble emissions, despite the complex acoustic conditions typical of shallow marine environments. The integration of passive DAS monitoring with independent geophysical observations provides a robust framework for interpreting gas-related signals and seabed processes. These findings demonstrate that marine DAS represents a promising geophysical tool for monitoring of submarine volcanic–hydrothermal systems and offers important insights for the development of sub-seabed CO2 leakage detection in offshore CCS contexts.