Anchor Dragging: The Dominant Cause Today of Subsea Cable Damage
The conventional wisdom has been that trawlers are the primary culprit of outages. These ships deploy fishing nets attached to sand skies (my term) that slide along the sea floor. Typically they sink 40 centimeters or even more into the muck catching the very thin fibre optic cables. Sometimes the cables break. In other cases the crew intentionally cuts the cable in its haste to resume harvesting. It is illegal, but the sea has few spectators. BT studied causes of subsea damage in the vicinity of the UK using the AIS (automatic identification system) to track ships involved in incidents. The chart below shows that prior to 2006 fishing was indeed the primary villain. But an evolution has occurred. Global trade expanded over the period while at the same time governments and voluntary organizations like Kingfisher worked hard to protect subsea cables by providing accurate maps of cable routes. Since global trade has only expanded since 2010 it is likely that the trend has continued. Ship...