Subsea Cables & Internet Infrastructure

 National security analysts please note, there is no sabotage category because there are no credible cases of sabotage. The IPCC study estimates 3,224 subsea fibre optic cable repairs over the last 18 years. It classifies 84% of outages as caused by fishing and anchors, 5% due to abrasion, 4% due to plant failure (subsea optical amplifiers or PFEs), and 7% due to geological disturbances such as turbidity currents induced by earthquakes or heavy rains or debris slides in subterranean caverns. Abrasion often leads to shunt faults where water reaches the power conductor.

A fibre optic subsea cable is encased in a polyethylene sheath. Most damage due to fishing trawlers, current abrasion, and anchors occurs in water depths 1,000 meters or less. Hence cables laid or buried in shallow waters are usually single or double armored to protect them. The armor consists of galvanized or stainless steel wires wrapped around the white polyethylene layer. Galvanized steel wire has a zinc coat that resists salt water corrosion. While armor does protect against abrasion and small mechanical forces, it is not strong to prevent the cable being torn by sea floor trawler net or a dropped or moving anchor.