The ignition and evolution of a giant submarine gravity flow

Submarine gravity flows are ubiquitous across the seafloor, occurring in all sizes and are the primary mechanism for transporting sediment from the shelf to the deep ocean. Giant flows are an enigmatic phenomenon because they often do not originate from an appropriately large landslide. Theoretical arguments propose that giant events can ignite from much smaller flows. However, quantifying how much a flow can enlarge is problematic due to their extreme size. Here, we reconstruct the properties and evolution of a giant gravity flow by mapping its traces from source to sink. The initial failure (~ 0.8 km 3 ) entrained ~ 200 times its starting volume: catastrophically evolving into a giant flow with a total volume of ~ 162 km 3 with estimated flow speeds between 15–30 m/s, and a run-out of ~ 2000 km. The entrainment of mud was the critical fuel for ignition, which promoted run-away flow growth and extreme levels of erosion.