The largest landslide on Earth displaced enough soil to cover an entire megacity in one event.

The Earth's history spans over 4.5 billion years, during which our planet has experienced numerous dangerous and large-scale events. One such event occurred around 60,000 years ago near the coast of Northwest Africa when a massive avalanche struck beneath the water, according to IFLScience.

It is known that it all began with 1.5 cubic kilometers of sediment that cascaded down the Agadir Canyon — one of the largest canyons in the world. As this volume of sediment traveled through the 450 kilometers of the underwater canyon, it increased in size by 100 times — ultimately displacing an astonishing 162 cubic kilometers of material. For comparison, this would be enough to completely cover a major metropolis in mud.

The event has been named Bed 5. However, researchers note that there have been even larger events in the history of underwater landslides: for instance, the Storegga landslides displaced a total volume more than 20 times that of the Bed 5 event. But what was remarkable about Bed 5 was that, unlike other events which typically occurred in stages, it shifted the entire mass all at once.

According to Dr. James Hunt from the UK's National Oceanography Centre, the Bed 5 event was an underwater landslide that primarily transformed from a large cohesive mass into a more diluted flow of sediment. This sediment surged through the entire canyon and then down into the underwater basins leading out from the canyon.

The event carved a path dozens of meters deep and several kilometers wide, displacing more and more mass. The extreme erosion led to incredible swelling. Dr. Hunt mentions two hypotheses regarding how such landslides eventually settle on the ocean floor. One suggests they settle due to the turbulence of the fluid, while the other likens their movement to a debris flow. However, scientists now believe there may be another possibility. Based on what Bed 5 indicates, flows may also transition from one state to another.

Researchers point out that such events in the planet's history are actually quite rare: approximately once every 50,000 years. They do not occur randomly; they require the accumulation of sediment, and researchers believe this occurs during periods between glaciation and the melting of the planet.

According to Dr. Hunt, the likely consequences of such a landslide would be tsunamis, but researchers are uncertain about their scale. The speed of the landslide and the volume of water displaced are crucial for modeling the scale of the tsunami. Something falling into the water, such as a landslide from a volcanic island into the ocean, could have more severe consequences than a larger underwater landslide that is already beneath the waves.

Researchers also note that we still have much to learn about these catastrophic events occurring beneath the water's surface. However, scientists hope that we will soon know a little more.