Summary of British Article On The Causes of Subsea Cable Damage & Outages

 1. Damage to cables is often the result of a cascade of events. For example, the 2006 Taiwan Earthquake pushed coastal sediments down a steep slope and triggered a massive landslide that traversed over a hundred kilometers. In many cases snapping deep sea cables like they were toothpicks. The sediment build up is due to Taiwan's heavy rains that carry eroded soil to the sea.

2. Lots of subsea faults arise from events that unfold over years such as deep sea abrasion of the outer sheaths of a cable. A cable may rub against a rough surface on the ocean floor for years until the polyethylene layer and the wound steel strands are removed and water hits the copper power conductor.

3. Another interesting example is the Congo Canyon where the Congo river deposits sediments offshore that high spring tides or flooding push down the undersea canyon and crush subsea cables.

4. Volcanoes during discharges have buried cables in molten lava. Also pose a danger to cable landing stations and terrestrial back haul. A good example is Tonga where an eruption buried a long stretch of the island's only international cable.

5. There is a strong correlation between sea depth and certain kinds of subsea cable damage. Fishing and anchor dragging clearly account for the majority of cable faults and those incidents almost always occur in one thousand meters or less of sea depth. This is why 2Africa and other modern systems are buried in any water that is a thousand meters or less. See the chart below.

6. Most abrasion occurs in waters exceeding one thousand meters deep. The oceans have conveyor belt current cycles which distribute heat around the globe. The AMOC warms Europe and then dives deep into the ocean to return to the South Atlantic. So currents can be quite strong plus there is less sediment in the deep sea so more opportunity for rocks to peel off the protective layers of cables.

For the full article, which is very long, click here: https://www.sciencedirect.com/science/article/pii/S0012825224003003.







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