NEW YORK, USA: Investors should urgently diversify the web of undersea cables that serve as the world's information and banking arteries to address soaring demand and piracy concerns and lessen the risk of catastrophic outages, a new report says.

Here are some facts about undersea communications cables.

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Nearly all international communications including global financial market transactions and the Internet are routed through a small number of cables buried deep in the oceans.

The submarine cable network is designed to be resilient, but outages can disrupt a wide range of activities such as banking, airline bookings, Internet shopping, education, health, defence, and communications.

Cable protection
Nearshore, cables need protection from shipping, fishing and other activities. To reduce risk, cables are identified on nautical charts and may be placed within a "protection zone" where activities harmful to cables are banned.

Seventy percent of all cable faults are the result of fishing and anchoring. Owners and operators of cables, typically telecoms utilities, co-operate with fishing, undersea mining, oil and gas, dredging, and other offshore industries to reduce the number of incidents damaging to cables.

Cables can also be broken by earthquakes, undersea avalanches and sometimes shark or fish bites. 

How cables work
Modern submarine telecommunications cables rely on pure glass fibres by which light is transmitted.

Because the light signal loses strength en route, repeaters are installed along the cable to boost the signal.

New systems rely on optical amplifiers, glass strands containing the element erbium. Strands are spliced at intervals along a cable and then energized by lasers that cause erbium-doped fibres to react and boost optical signals.

Cable size
Cables are small; deep-ocean types without protective armour are typically 17-20 mm in diameter, similar to a garden hose or beer bottle cap.

Armoured fibre-optic cables may reach 50 mm in diameter. In contrast, submarine oil/gas pipes reach 900 mm in diameter, and fishing trawls typically range over 5,000 -50,000 mm in width.

Cable lengths vary; one of the longest is the SEA-ME-WE 4 system at about 20,000 km (12,500 miles).

Old cable systems:
1866: First trans-Atlantic cable carried telegraph messages at seven words a minute.

1956: First trans-Atlantic telephone cable initially had a capacity of 36 telephone calls at a time; calls cost $12 for the first three minutes.

Modern cable systems:
1988: First Atlantic fibre-optic cable, TAT-8, had a capacity for 40,000 simultaneous phone calls, 10 times that of the last copper cable.

Today: Each fibre pair within a cable has the capacity to carry digitised information including video that is equivalent to 150,000,000 simultaneous phone calls. 

Hazards and Climate Change
Cables may be exposed to more hazards under global warming, Increased windiness and related wave/current activity, more intense hurricanes, cyclones, typhoons, changes in marine activities, e.g. commercial fishing

Legal status
Cables are protected by international treaties: The International Convention for Protection of Submarine Cables of 1884, the Geneva Conventions of the Continental Shelf and High Seas of 1958 and the UN Law of the Sea Convention of 1982.

The treaties provide freedom to lay, maintain, and repair cables outside of a nation's 12 nautical mile territorial sea and obliges nations to impose criminal and civil penalties for intentional or negligent injury to cables.

(Source: The International Cable Protection Committee Ltd, http://www.iscpc.org/)