A sunset viewed from Kure Atoll, located near Midway Atoll in the Northwestern Hawaiian Islands. An atoll is an island of coral that encircles a lagoon partially or completely. Image credit: Robert Schwemmer, NOAA National Marine Sanctuaries
Turbidity currents can be set into motion when mud and sand on the continental shelf are loosened by earthquakes, collapsing slopes, and other geological disturbances. The turbid water then rushes downward like an avalanche, picking up sediment and increasing in speed as it flows.