New research from the University of Liverpool in the UK has uncovered a massive underwater avalanche that occurred 60,000 years ago along the northwest coast of Africa, including Morocco.
The study details how the avalanche started as a small seafloor landslide and grew more than 100 times in size, causing significant destruction as it traveled 2,000 kilometers across the Atlantic Ocean seafloor.
This discovery offers unprecedented insights into underwater avalanche, a mysterious natural phenomenon, as underwater avalanches, unlike their terrestrial equivalents, are invisible and challenging to measure.
Dr. Chris Stevenson, a sedimentologist from the University of Liverpool’s School of Environmental Sciences, co-led the research team.
The team successfully mapped the entire path of this ancient avalanche, which began in the Agadir Canyon off Morocco’s coast.
Initially, the landslide had a volume of about 1.5 km³, but as it moved, it picked up boulders, gravel, sand, and mud, growing into a massive force that carved through one of the largest submarine canyons in the world.
The avalanche was so powerful that it eroded the entire 400-kilometer length of the canyon and traveled another 1,600 kilometers across the ocean floor.
Dr. Stevenson described the magnitude of the event: “Imagine an avalanche the size of a skyscraper moving at over 40 mph from Liverpool to London, digging a trench 30 meters deep and 15 kilometers wide, destroying everything in its path.”
The natural process plays a disruptive role as it transports sediments, nutrients, and pollutants across the Earth’s surface and poses significant risks to seafloor infrastructure like internet cables.
The research team analyzed over 300 core samples and used seismic and bathymetric data to map the avalanche’s path and calculate its growth factor.
Dr. Christoph Bottner, a Marie-Curie research fellow at Aarhus University in Denmark, noted that the growth factor of this avalanche was significantly higher than typical snow avalanches or debris flows.
The findings suggest that such extreme growth might be a characteristic behavior of underwater avalanches, warranting further investigation.
Professor Sebastian Krastel, head of Marine Geophysics at Kiel University in Germany, emphasized the importance of these findings for assessing the geohazard risks to critical infrastructure like internet cables.
The research challenges previous assumptions that only large slope failures could lead to giant avalanches, revealing that even small initial events can grow into powerful and extensive disasters.