A team including Durham scientists has published research on the longest underwater avalanche ever recorded. The avalanche transported sediment 1,200 km into the ocean, and would have gone unnoticed had it not broken two seabed telecommunication cables off the coast of western Africa.
The event happened in January 2020 but the research into its triggers and effects has only just been published.
Professor Pete Talling from Durham’s Department of Geography told the BBC, “we had a series of oceanographic moorings [in the Congo Canyon] that were hit by the event, which broke them from their anchors.
“Because [the avalanche] erodes the seabed, it picks up sand and mud, which makes the flow denser and even quicker.”
This kind of underwater avalanche is also known as a turbidity current. It is thought that this particular event was triggered by the Congo River flooding in 2019, which was the worst for 50 years.
Understanding the dynamics behind such powerful submarine turbidity currents is necessary to analyse and predict hazards to strategic telecommunications cables. Seafloor cables carry over 99% of global data traffic between continents, facilitating the internet, financial services, and cloud data storage.
Durham researchers, led by Prof. Talling, have been developing methods to collect data on massive turbidity currents around the world. Their data show that turbidity currents in the Congo Canyon can last for more than a week, and that submarine flows have broken or damaged manmade seabed structures since the 1880s. The 2020 event followed 18 years without any problems.
Durham scientists have been actively advising cable companies during the most recent cable repairs, as well as creating measures to mitigate such damage in the future.
The team has secured NERC funding for 6 more research cruises, 4 of which will take place off the coast of West Africa. Level 3 Advanced Geophysics students have had the opportunity to analyse the most recent data, continuing the research.
Image: Peter Talling