Seabed seismographs unlock mysteries of longest runout sediment flows

Durham University scientists have made a groundbreaking discovery in marine geoscience, revealing unprecedented insights into the dynamics of Earth’s longest runout sediment flows.

By using seabed seismographs placed safely outside the destructive paths of powerful underwater avalanches of sediment, researchers have successfully monitored turbidity currents—a natural phenomenon that shapes deep-sea landscapes, damages telecommunication cables, and transports large quantities of sediment and organic carbon to the ocean floor.

The study recorded two massive turbidity currents that traveled over 1,000 kilometers through the Congo Canyon-Channel, moving at speeds of up to 7.6 meters per second.

These flows lasted over three weeks and marked the longest runout sediment flows ever directly observed on Earth.

This achievement provides critical new data on the duration, internal structure, and behavior of turbidity currents, advancing our understanding of this powerful geophysical process.

This breakthrough opens up new possibilities for studying one of the most significant yet poorly understood processes shaping our planet.

By using ocean-bottom seismographs, researchers can now safely and effectively measure these extraordinary events in more detail than ever before.

Lead author of the study Dr. Megan Baker of Durham University, said, “This multidisciplinary work brought together geologists, seismologists, and engineers to advance our understanding of powerful turbidity currents through first-of-their-kind observations using ocean-bottom seismographs.

“This approach enables the safe monitoring of these hazardous events and will help us learn where and how often turbidity currents occur globally.”

The research team, which included researchers from Newcastle University, GEOMAR Helmholtz Center for Ocean Research, National Oceanography Center, Georg-August-University, Deutsches GeoForschungsZentrum GFZ Potsdam, IFREMER, Université Paris-Saclay, TU Wien, University of Hull, University of Southampton and Loughborough University, successfully used ocean-bottom seismographs—instruments that are placed on the seafloor to record seismic signals generated by the turbidity currents.

This innovative approach allowed the researchers to capture detailed information on these flows without risking damage to expensive equipment, as has been the case with previous attempts.

The use of these seismographs marks a major step forward in monitoring hazardous seabed events, offering a cost-effective and long-term method for studying turbidity currents and their impacts.

The findings also reveal the global significance of these underwater flows. The turbidity currents studied in this research not only shape deep-sea landscapes but also play a crucial role in the transport of organic carbon and sediment to the ocean floor, with significant implications for deep-sea ecosystems and global carbon cycles.

The study shows that despite substantial erosion of the seafloor, the front of these massive flows maintains a near-constant speed and duration, efficiently moving organic material and sediment vast distances to the deep-sea.

The study also challenges traditional models of turbidity current behavior, suggesting that the flows can maintain a consistent speed and duration even as they erode the seabed.

This finding calls for a revaluation of existing models that have been based primarily on shorter, shallower flows.

The research is published in the journal Geophysical Research Letters.