Formation and sedimentation of ash fingers below volcanic clouds: insights from lock-release experiments

The sedimentation of volcanic ash produced by explosive volcanic eruptions is commonly modelled as being governed by particles falling individually. However, collective settling processes, such as settling-driven gravitational instabilities can shorten the atmospheric residence time of ash. These instabilities generate downward-propagating plumes known as fingers that descend faster than the terminal fall velocities of ash particles, resulting in enhanced sedimentation that can affect deposit in