turbidity current

Gravity-driven current in air, water, or other fluid resulting from accumulation of suspended material, such as silt, mud, or volcanic ash, and imparting a density greater than the surrounding fluid. Marine turbidity currents originate from tectonic movement, storm waves, tsunamis (tidal waves) or earthquakes and move rapidly downward, like underwater avalanches, leaving distinctive deposits called turbidites. They are thought to be one of the mechanisms by which submarine canyons are formed.