Dynamics of giant volcanic ash clouds from supervolcanic eruptions

Abstract

The largest explosive volcanic eruptions that have occurred on Earth generated giant ash clouds from rising plumes that spread in the stratosphere around a height of neutral buoyancy, with estimated supply rates that are in the range 1011 to 1013 m3/s. These giant ash clouds are controlled by a balance between gravity and Coriolis forces, forming spinning bodies of nearly fixed proportions after a few hours and are initially insensitive to stratospheric winds. In contrast, volcanic plumes from eruptions with small to intermediate magnitude spread as inertial intrusions under the influence of stratospheric winds, with the Earth's rotation being unimportant. In the largest eruptions the giant ..