University of Minnesota
Aerospace Engineering and Mechanics
Winter 1997 Seminar Series


The Fluid Mechanics of Volcanic Eruptions


Herbert Huppert Cambridge University


Institute of Theoretical Geophysics
Department of Applied Mathematics and Theoretical Physics



Abstract

Volcanic eruptions occur episodically on the surface of the Earth, and occasionally result in considerable loss of life and extensive destruction of property. The talk will commence with a description of the size and significance of magma chambers, which are large storage reservoirs of partially liquid rock that exist beneath all volcanoes and act as their power source. Various physical phenomena which occur in the chamber and lead to an increase in pressure will be described. Eventually the overlying rock can no longer withstand the additional stresses, and an eruption ensues. Liquid magma rises and the resulting pressure release can lead to a significant gaseous component in the melt. Important heat transfer processes can occur between the hot, flowing mixture and the relatively cold surrounding rock so that in some cases the fluid freezes in the conduit and the eruption ceases. The plume which erupts into the atmosphere can take two forms. Either the outflow is sufficiently buoyant that it can transform thermal energy, through entrainment, into potential energy and rise high into the atmosphere, or heavy ash particles dominate the motion and a hot, ground-hugging, particle-rich flow results. As a rising plume penetrates the atmosphere the plume eventually reaches a level where it is no longer positively buoyant. Near that level it intrudes laterally and can spread many thousands of kilometers, carried by the prevailing winds, continuously shedding relatively heavy ash particles. The talk will be illustrated by a cine film and colour slides of both real volcanic eruptions and their laboratory simulation.

Friday, January 24, 1997
225 Akerman Hall, 2:30 - 3:30 p.m.


Refreshments served after each seminar in 227 AKERMAN HALL .
Disability accommodations provided upon request.
Contact Leslie Petrus : Secretarial Assistant.

petrus@aem.umn.edu (612) 625-8000.