Giant submarine avalanche reshaped Atlantic seafloor off Morocco 60,000 years ago

Approximately 60,000 years ago, a significant underwater avalanche occurred in the Agadir Canyon, located off the coast of Morocco. This event began as a minor seafloor slide but escalated into a massive torrent of sediment and boulders, reaching heights of 660 feet and speeds of 40 mph. The avalanche traveled through the 250-mile-long canyon and extended an additional 1,000 miles along the Atlantic seabed, resulting in a dramatic transformation of the seafloor. Researchers utilized sediment data from over 300 core samples collected during four decades of research, alongside seismic and bathymetric data, to trace the avalanche's path. Their findings revealed that the avalanche expanded more than 100 times its original size, a stark contrast to terrestrial avalanches that typically grow only four to eight times. This phenomenon suggests a unique behavior associated with underwater avalanches, which may have implications for understanding similar events. The study, published in the journal Science Advances, marks the first comprehensive mapping of an underwater avalanche of this magnitude. The resulting map illustrated the avalanche's extensive reach, covering an area comparable to the size of Oregon with over 3 feet of sediment deposited on the seafloor. The researchers emphasized the challenges in measuring underwater avalanches, which often go unnoticed. They warned that a modern equivalent of the Agadir Canyon event could pose significant risks, highlighting the need for further research into the dynamics of such underwater phenomena.