Ph.D. project proposal

Soufriere Hills volcano on the Caribbean Island of Montserrat shows ongoing volcanic activity since 1996, in a well-established pattern of dome growth and dome collapse. In the last few years, several international research projects focused on Montserrat and made Soufriere Hills volcano one of the most intensely studied volcanoes wordwide. The Volcano Seismology Group at Leeds is involved in several international research initiatives on Montserrat funded by NERC, the European Commission under the MULTIMO project and by the National Science Foundation in the US.

So-called long-period seismic events (LPs) play a key role in the understanding of the internal dynamics of the volcanic system. They show a well-established pattern of swarms always preceding mayor dome collapses and have therefore a great potential to be used for forecasting of volcanic hazard. While the seismic wavefield associated with low-frequency events in the conduit and in the volcanic edifice is well understood, their actual trigger mechanism is still an open question.

This PhD project will be concerned with the modelling of several such mechanisms ranging from water - magma interaction to brittle failure of magma near the glass transition. The project aims to uncover the interaction of magma and elastic parameters to constrain the physical models behind cyclic activity and the trigger mechanism of low-frequency seismic events.

The student will be provided with training in analytical and numerical modelling techniques, applied to seismic wavefields and pressure
variations in magma-gas mixtures. Volcanic monitoring experience will be gained on the Caribbean island of Montserrat.  Due to the
multi-national funding and co-operation of this project, the student will be part of a colourful and multi-disciplinary group of scientist from the US, the UK and several (other) European countries.
 

Illustration of magma flow modeling inside a vocanic conduit.
According to seismicity analysis, low frequency events occur around 1500m depth in the conduit (left hand-side figure), triggered by the brittle failure of melt. Above the depth of failure, the magma at the wall is friction controlled wheras no slip condition was applied below (second figure).
Brittle failure induces gas loss at the wall which in return will modify the magma flow. As illustrated in the first snap-shot, flow velocity is considerably reduced as well as the gas volume fraction (second snap-shot) while the magma density increases (third snap-shot). Due to the change in boundary conditions, the conditions for brittle failure remain in a narrow depth range (last snap-shot).

Neuberg, J., Luckett, R., Baptie, B., and K. B. Olson, 2000, Models for tremor and low-frequency events on Montserrat, J. Vol. Geotherm. Research, 101, 83-104.