By Luis Monzon for IT News Africa

A recent study conducted by Professor Peter J. Talling and a team from the Departments of Earth Sciences and Geography, from the University of Durham in the UK, co-led by Angola Cables and supported by the Vodafone Group, British Telecom, NERC Environmental and others, has delivered important findings presenting valuable insights for the routing and protection of future subsea cables.

In January 2020, the South Atlantic 3/West Africa (SAT-3/Wasc) cable, linking Africa to Portugal and Spain was hit by a breakdown in Gabon, whilst the West Africa Cable System (Wacs) that connects South Africa to the United Kingdom saw an outage off the coast of the DRC Congo.

In March, the WACS cable experienced a further break affecting international bandwidth. Whilst many ISPs suffered extended outage periods, most of the major mobile operators were able to mitigate the impact on internet traffic due to their redundancy measures and were in a position to redirect data traffic to other subsea cable networks. Large telcos and mobile operators often employ a divergent strategy to ensure they have alternative routings in place should one of their data-carrying cables be affected.

The cable fault on the SAT-3 was likely caused by an exceptionally large and powerful submarine mudslide that originated at the mouth of the Congo River, just 10 days after the Congo River recorded its largest flood since the 1960s. Sand and mud from the river flood were presumably remobilised, triggering the submarine mudslide that flowed through the offshore Congo Canyon.

The canyon is one of the largest underwater canyons on earth, cutting across the continental shelf of West Africa for 85 kilometres until it reaches the shelf edge, then continues down the slope and ends 280 kilometres from its origin. At its deepest point, the V-shaped canyon walls are 1100 meters in height.

According to observations by Professor Talling and the team, “the data that we recovered from the seabed sensor and mooring data sets within the Congo Canyon have revealed that the undersea mudslide is possibly the longest recorded sediment flow yet measured in action on our planet.”

The January 2020 event caused 9 of the oceanographic moorings to surface. By combining the timings of when moorings reached the sea surface and the cable breaks, Professor Talling and his team were able to calculate the flow speed of the massive undersea avalanche.

It has been estimated that following the initial mudslide in the canyon, the moving sediment increased in speed from 5 m/s in Angolan waters in the upper canyon, to reach 8 m/s in the deep ocean, at water depths of 4-5 km – running out some 1,200 km from the river mouth.

“Depending on the proximity of cable repair vessels, outages can often take a number of weeks to repair resulting in costly losses to economies impacted by such breaks,” notes Talling, “Gathering evidence and the recorded data in studies such as these are critical to understanding the nature of such subterranean events, and how the subsea cable industry can better provide more durable solutions in keeping the cables – and the world connected.”

It is estimated that around 1.2-million kilometres of subsea cable carrying power and transmitting data currently transverse continents and geographies across the world. Most of these cables are either buried in the seabed or rest on the ocean floor.

Nearly 75% of the damage caused to these cables are the result of being snagged or damaged by the anchors of ships. Deep see cable faults in water depths of more than 1,000 metres below sea level, are almost always caused by natural events such as current abrasion, underwater landslides and underwater seismic activity.

Often the problem with deep water faults is that they are not as easy to detect and can impact multiple cables – making recovery and repair efforts both lengthy and costly to cable operators.

Important undersea cable breaks – again

By Stefan Mack for Briefly

The West African Cable System (WACS), an undersea Internet cable which is critical to South Africa’s communications infrastructure, has broken again.

The cable had broken earlier this year and resulted in a notable slowdown in SA’s internet speeds. A break has been reported in the cable, but it is not yet clear where the break is or if the damage is in the underwater part of the cable. The repairs would take longer and be more expensive underwater. If the break is on land it would be significantly easier and cheaper to repair.

The damage to the cable could leave some internet users without access, depending on the Internet Service Provider (ISP). Earlier this year, the same cable was damaged when pressure from a mudflow from the Congo River into the ocean.

Undersea cable repair could take up to a week

By Lisa Isaacs for IOL 

As gale-force winds let up slightly in Cape Town on Monday, the ship expected to effect repairs to underwater cables that failed and left parts of the continent with slow Internet, departed from Cape Town Harbour.

Strong winds battered the Cape over the past few days, trapping the cable repair ship due to effect repairs on the West Africa Cable System (WACS).

The South Atlantic 3 (SAT-3) undersea fibre cable was damaged near Libreville, Gabon, while WACS was damaged near the Congolese coast, causing slow Internet speeds across parts of Africa since last Thursday.

South African social media users reported problems with MTN’s and Vodafone’s networks.

The SA National Research and Education Network (SA NREN) tweeted yesterday afternoon that the cable vessel was finally on its way to the cable depot quay.

“The weather situation in Cape Town has improved and the port reopened. The cable vessel expects to shift to the cable depot quay.”

When the vessel has loaded and departed, the expected duration to the location of the break is around six days.

Fixing the break will take another week at least, according to the SA NREN.

Internet service provider Afrihost, in a network status update yesterday, said it had purchased additional international bandwidth on other undersea cables to restore internet services to as close to normal as possible.

“This means that we will not be reliant on repairs to the damaged cables to deliver better international speeds and latency.

“Our team is currently working through the night to implement the additional capacity this evening or early tomorrow morning.”

At the weekend, web company Amphibic Design said: “Service providers are diverting traffic through another undersea cable, SEACOM/EASSY, which runs alongside the eastern coast of Africa.

“This ensures that South Africans can still access the internet, but it is also slowing internet access. It is unclear when the cables will be operational again.

Both the WACS and SAT3 cables providing international connectivity between South Africa and international locations were knocked out on Thursday.

These breaks are having a major impact on internet connectivity.

The WACS cable lands in South Africa at Yzerfontein in the Western Cape and the SAT3/WASC system enters the country at Melkbosstrand.

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