Longest-Runout Undersea Sediment Flows Analysed in Unprecedented Detail

An international team of researchers led by GEOMAR Helmholtz Centre for Ocean Research Kiel and Durham University has successfully captured the internal structure of the longest-runout sediment flow ever recorded on Earth.

Using seismic measurements, the researchers have for the first time been able to analyse in detail the internal structure of these tens to hundreds of kilometres long turbidity currents - an oceanographic phenomenon that has been studied for almost a century, but never directly observed.

The team deployed seismometers in October 2019 in the Congo Canyon and Channel off the west coast of Africa - one of the largest and deepest submarine canyons in the world. The instruments were placed several kilometres outside the canyon-channel axis, beyond the destructive reach of the currents, allowing them to record the seismic signals generated by flow turbulence and associated sediment transport.

The researchers tracked two turbidity currents moving at speeds of 5 to 8 metres per second (m/s) over a distance of 1,100 kilometres - from the mouth of the Congo River through the Congo deep-sea fan and canyon system. These are the longest-runout sediment flows ever recorded. The flows also damaged several submarine cables in January and March 2020, disrupting internet