Current: Critical submarine cable infrastructure

What happens if a submarine cable is interrupted?

Due to the coronavirus pandemic, the federal and state governments will once again adopt new quarantine rules. This also has an impact on staff in critical infrastructure. If you look at the list published today by RND, you will find all the buildings, facilities and organisations that are important to our lives. The federal and state governments have defined nine sectors. People concerned about maritime safety will find maritime and inland shipping as well as logistics under transport and traffic, but does Berlin have an eye on what can happen at sea?

How do you protect this critical subsea cable infrastructure? In March, the Royal Navy announced that a new ship is to take over surveillance in both British and international waters. Commissioning is planned for 2024. The main focus will be on undersea cables that ensure internet and communication links and economic transactions with other countries. It has long been rumoured that Russia could be attempting to sabotage cables with submarines because British and US intelligence services have discovered Russian submarines in the vicinity of Atlantic submarine cables. NATO had already drawn attention to this in 2017.

And now Reuters is reporting that the South Pacific archipelago of Tonga could be cut off from the rest of the world for weeks due to difficulties repairing its only undersea communications cable, which an operator says ruptured during a massive volcanic eruption. The eruption of the Hunga Tonga-Hunga Ha'apai volcano on Saturday caused a tsunami that severed the link some 37 kilometres off the coast.

This proves the vulnerability of underwater fibre optic cables, which have become indispensable for global communication thanks to their 200 times higher data transmission capacity than satellites. Whether the repair will work depends on a specialised ship, RELIANCE, which will only arrive in Port Moresby, the capital of Papua New Guinea, in a few days' time. The ship belongs to the US company SubCom, a manufacturer of submarine cable networks, which is responsible for the maintenance and repair of more than 50,000 kilometres of cable in the South Pacific.

And it's not easy: what is quick for an experienced technician on land is very complicated for a cable on the seabed. The fault must first be found by feeding a light pulse into the cable. The fault is located where the pulse bounces back. The location can be localised by measuring the propagation time. For the repair, the cable is hooked by a submersible or a diving robot and pulled up for repair.

More than 99 % of global international data traffic is still handled via a network of around 280 submarine cables with a length of more than one million kilometres (621,000 miles).

Sources: Reuters / RND / Behördenspiegel / Praveen Menon / Tom Westbrook