Measuring Marine Electromagnetic Fields: Systems and Applications

This paper explores the application of highly sensitive passive Electromagnetic Field (EMF) measurement systems to address critical challenges in maritime coastal areas, including environmental impact assessment, infrastructure integrity, and underwater surveillance and detection. We present the development and deployment of three innovative systems: PASSEM (vessel-towed), STATEM (static seafloor), and an ROV-mounted system, capable of measuring EMF variations at very low levels. These systems enable the accurate characterization of EMF signatures from anthropogenic and natural sources, crucial for understanding their effects and origins. Results from the SPECIES project demonstrate the systems' efficacy in assessing the EMFs emitted by subsea power cables, supporting sustainable marine energy development. Corrosion detection experiments highlight the systems' sensitivity to subtle EMF gradient changes, enabling the monitoring of cathodic protection evolution. Furthermore, the detection of a cargo vessel using STATEM data highlights the systems' potential for underwater surveillance and broader detection capabilities relevant to defense applications. This research establishes the potential of passive EMF measurement as a powerful tool for comprehensive marine infrastructure management, contributing to the safety, longevity, and environmental sustainability of maritime coastal areas.