Subsea Cables & Internet Infrastructure

It turns out that the CS Sovereign, a Global Marine ship whose home port is Portland, UK, is sailing down the West African cost to Abidjan to fix WACS. Why was the Sovereign chosen when it is so far away? Every cable system has one or two storage depots where fibre is kept for repairs. WACS spare fiber and other repair supplies are kept at Brest, France. Now Orange Marine has a cable ship, the well known Léon Thévenin, at anchor in Capetown, South Africa. But if the supply depot is in Europe, a nearby cable ship becomes useless. It all makes eminent sense because WACS connects both the UK and Lisbon to West Africa and the cable was laid from the UK to Lisbon and down the West African coast. So the starting point for deployment was Europe and hence that is where the spare supplies are located. However, this is a severe logistical mistake since most WACS outages occur between Senegal and Congo, not in European waters.

The cable ship repair permit has been granted. It is expected to arrive off Abidjan on July 22nd. The 2Africa cable will be the first repaired despite its outage being limited to the Cote d'Ivoire branch. WACS repair is expected to begin at the month's end. The ASN Ile D'Ouessant cable ship left Capo Verde last week and will arrive in the Gulf of Guinea this Wednesday.

A turbidity current is the likely culprit for the WACS trunk outage. The same holds true for the 2Africa Ivory Coast branch failure. The Taiwan earthquake of December 2006 is instructive in this regard. The 22 knocked out cables failed in sequence over the course of several hours. So the sheer force of the earthquake was not responsible. Instead, the seismic event caused sediment to begin moving down the undersea slope of Taiwan's continental shelf. This was not a gentle slope, but rather the steep sides of the Kaoping subsea canyon, which is 4 kilometers deep. As the chart shows, cables went dark in sequence radiating from the epicenter outward as this undersea tidal wave traveled down the sides of the subsea canyon. The turbidity current traveled at speeds ranging from 3.7 meters per second to 5.7 meters (roughly 20 kilometers per hour). The sequence of events suggests there were at least 2 and probably turbidity currents involved.  It is probably not a coincidence ...

Heavy rains in Côte d'Ivoire likely caused rivers to dump large amounts of sediment at high speed into the Atlantic. These undersea mud Tsunamis accelerate down the deep gradient of the continental shelf off Abidjan and destroy anything in their path. In particular, they displace the sea floor up to several meters. It is likely that a turbidity current effectively disinterred the WACS trunk and severed it. The main value of WACS is moving traffic between Africa and Europe. So this outage imposes severe hardship on African ISPs. Outages off Côte d'Ivoire's shore are common and have disrupted Internet service in the country many times. For example, in 2024 a debris slide in the subterranean canyon off Abidjan took out four cables, including WACS. Côte d'Ivoire really needs high capacity fibre optic links into neighboring countries to better weather these network crises.

Abidjan clients on WACS report an outage began 4 AM local time today. Outage began with a severe drop of 385 volts. Investigation shows the fault lies in segment S3C between the first and second repeater on the Ivory Coast branching unit. So the outage should only affect Cote d'Ivoire. A ship has been dispatched to fix it. Two years ago four cables were severed off Abidjan due to a debris slide in the subterranean cavern known as Le Trou Sans Fond. Also a 2Africa outage started 1:30 PM Abidjan time. More information will be provided as it becomes available. First map below is 2Africa. Second is WACS. 

 2Africa; Senegal/Portugal; 100G; $18.5K; 2 Years. WACS; Ivory Coast/Portugal; 10G; $8,250; 3 Years. 2Africa; Nigeria/South Africa; 100G; $24,750; 1 Year. Equiano; Nigeria/South Africa; 100G; $20K; 1 Year. Equiano; Nigeria/Portugal; 100G; $19.5K; 2 Year. 2Africa; Ghana/Nigeria; 100G; $23.5K; 1 Year. 2Africa; Ivory Coast/Portugal; 10G; $10,500; 1 Year. 2Africa; Ivory Coast/Portugal; 100G; $33.5K; 3 Year. Remarks: 2Africa CLS cross connects are $150 max. WACS cross connect charges are five digit.

***5x 100Gs; CT1/LS1; Equiano The Stable Cable; $21K MRC Per Wave ***1x 100G; Johannesberg Teraco/London; WACS; $29.5K;Protected Back Haul; Photo credit: submarinenetworks.com