| Abstract |
Hydrothermal eruptions occur when hot fluid just below the ground surface is exposed to atmospheric conditions. As it moves to the lower-pressure atmosphere, the fluid boils; the consequent expansion as the denser liquid phase flashes to steam produces high vertical speeds and lifts the rock particles which surround the vent. A mixture of liquid water, vapour and solid particles is ejected into the atmosphere, and returns to the ground surface, where the solid particles are distributed over an area which depends on their size and the vigour of the eruption. This paper includes a discussion about the conceptual modelling of such a process, a proposal for quantitative model equations which might be used to describe the phenomenon, and some preliminary calculations using the mathematical model. Some attention is paid to the fluid conditions which may pertain at the base of such eruptions and which factors are important in the flow model. |