The conditions for magma-chamber rupture and volcanic eruption during unrest periods

Theme: Natural & Biological Hazards
Primary Supervisor:

Agust Gudmundsson

Earth Sciences, RHUL

Project Description:

During most volcanic unrest periods, the magma chamber does not rupture, so that no dike is injected. During some unrest periods, however, the stress concentration around the chamber results in rupture and dike injection. The conditions for this latter to happen depend on stress concentration and, in turn, on the elastic energy (the strain energy and the external loading) accumulated in the volcano during the unrest. Once a dike is injected, its propagation path depends strongly on the local stress field in the volcano, which in turn is a function of the shape and pressure in the magma chamber as well as the mechanical layering of the volcano. Dike paths tend to be complex and most dikes become arrested, that is, never reach the surface to erupt. The chances of a dike reaching the surface depends, again, on the local stresses and, in particular, on the elastic energy accumulated in the volcano during the unrest.

This project combines compilation of (1) volcanotectonic field data, including data on active and fossil magma chambers, dikes, and mechanical layering and (2) geodetic (InSAR, GPS) data from unrest periods with (3) analytical and numerical models so as to forecast (a) the likelihood of a magma chamber rupture during a given unrest period, (b) the likelihood of an injected dike propagating to the surface to erupt, and (c), in case of an eruption, the likely size and duration of the eruption.

Policy Impact of Research:

To help in assessing hazards and making correct decisions during volcano unrest, the project addresses the following questions: 1. Is the magma chamber going to rupture and inject a dike? 2. Is the injected dike likely to reach the surface, and how large is the dike-fed eruption likely to be?

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