By Paolo Franchi In Memorandum Reports
Sensors to increase the security of underwater communication cables: a review of underwater monitoring sensors. Eleftherakis, Dimitrios; Vicen Bueno, Raul. CMRE-MR-2019-011. March 2020.
Underwater communication cables transport huge amounts of information between continents and countries that could not be transported through satellite communications (bandwidth limitations). They also transport sensitive information (financial, economic, political, military, etc.) hence representing a critical infrastructure that should be protected by all means. Although the cables are protected by international conventions, monitoring of the underwater environment where the cables lay is rare and any intervention/maintenance is usually driven by cable faults. Casual cable faults are mainly due to anchors and fishing. The necessity to regularly monitor the underwater area surrounding the cables is also highlighted in a number of reports, raising issues about possible future malicious attacks on the cables. The main objective of this report is to make an overview of different commercial -already available- sensors that could be potentially used for the monitoring and/or surveillance of the underwater environment following the route of the cables at regular intervals. The sensors studied in this report use several operation principles, such as acoustic, optical, magnetic and oceanographic. These sensors could be mounted on different platforms, such as Unmanned Surface Vehicles (USVs), Autonomous Underwater Vehicles (AUVs) and Unmanned Underwater Gliders (UUGs). Some commercially available unmanned surface and subsurface platforms are provided in the report. The report analyses a multi-threat case study for surveying a transatlantic cable of 13,000 km, which reaches water depths up to 4,000 m. The potential underwater threats involved are: divers, anchors, fishing trawls, submarines, remotely operated vehicles (ROVs) and AUVs. These threats could cause cable damages/failures or tampering to collect transmitted data. The report provides potential solutions on suitable sensors to monitor the cables against these threats. In addition, it presents ideas on the construction of periodic surveillance networks and permanent surveillance networks, and discusses also tampering monitoring issues. Finally, the report provides ideas on the different possibilities for enhancing the security of underwater cables. This foundation can be used in future more-detailed and specific studies on actually designing security measures.