A group of British scientists has found evidence of an underwater landslide that took place 60,000 years ago and triggered the longest flow of debris ever recorded, according to research published on the website of the journal Nature.

A massive volume of sediment that was dislodged off the northwest coast of Africa, travelled 1,500 kilometres across the ocean floor – the distance between London and Rome – without depositing any of its load on the sea bed over which it moved. It’s thought that the 150-kilometre-wide river of sand and mud was finally brought to a halt by a small but abrupt decrease in sea-floor gradient.

‘The volume of sediment transported by this flow in the deep ocean is difficult to comprehend,’ said Dr Peter Talling from the University of Bristol, lead author of the paper. ‘This mass was ten times that transported to the ocean every year by all of the Earth’s rivers.’

The project was funded by the UK government and a consortium of major oil and gas companies. ‘A flow such as this can easily destroy seafloor structures such as pipelines and telecommunications cables, so understanding where and when these flows occur is a major issue,’ said Dr Russell Wynn, who led the research project.

It isn’t clear exactly what triggers such vast movements of underwater mass, but it’s presumed that submarine landslides of this magnitude only occur every 10,000 years. Other submarine landslides have been documented off the coasts of Newfoundland in Canada, Hawaii and Norway.     


Kate Warburton

February 2008