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E338: Using petrology to inform modelling of volcano deformation (Lead Supervisor: Marie Edmonds, Earth Sciences)

Supervisors: Marie Edmonds (Earth Sciences) and Alex Copley (Earth Sciences)

Importance of the area of research:

Volcanic eruptions are often preceded and accompanied by ground deformation observable from space. Deformation data may be inverted for magma chamber volume (or pressure), depth and shape of magma chamber. Relatively simple magma chamber sources are generally used, such as spheres, sills and ellipsoids. Petrological studies of volcanic products and models of recharging magma reservoirs, however, show that magma chambers are rarely homogeneous, closed systems. The emerging view is of vertically protracted systems of crystal mushes where regions of crystals, liquids and exsolved volatile-rich fluids may exist.  Remobilisation of such systems during magma chamber recharge may take place shortly before eruptions.  The consequences of these processes for understanding contemporaneous deformation have not been explored in detail yet are important for understanding deformation data and for assessment of volcanic hazards.

Project summary:

This project is an exciting opportunity to combine petrological and geophysical observations with modelling of volcanic processes under the auspices of the multi-institutional NERC COMET group (http://comet.nerc.ac.uk). Examples of magma reservoir systems will be used as case studies to explore the consequences of complex magma reservoir geometries and reorganisation processes for ground deformation. Sensitivity of the output of deformation models to changing magma compressibility, loci of liquid lenses and storage of exsolved fluids in mush systems will be explored. The project will make use of detailed petrological studies of volcanic systems to place realistic constraints on magma storage and remobilisation prior to eruptions.

What the student will do:

A small number of volcanic systems will be targeted for detailed analysis, such as Okmok (Alaska), Soufriere Hills (Montserrat). Petrological data from the literature will be harvested to form a detailed picture of magma storage in the crust and the dynamical behaviour of the system during magma recharge. Petrological analysis will be carried out where necessary to characterise key parts of the system. The petrological information will be used to construct forward models with which to explore the ground deformation associated with magma recharge and withdrawal from such systems. In particular the project will explore the sensitivity of the ground deformation observed at the surface in the models to chamber depth, form, composition (mush, liquid, low density fluid) and organisation. The modelling will be applied to better understand deformation data acquired for eruptions of the target volcanoes and to explore the implications for volcano monitoring and hazard assessment.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Jay, J., F. Costa, M. Pritchard, L. Lara, B. Singer & J. Herrin, 2014. Locating magma reservoirs using InSAR and petrology before and during the 2011–2012 Cordón Caulle silicic eruption. Earth and Planetary Science Letters, vol 395, pp 254-266.

Cashman, K. V. & G. Giordano, 2014. Calderas and magma reservoirs. Journal of Volcanology and Geothermal Research, vol 288, pp 28-45.

McCormick-Kilbride, M. Edmonds, J. Biggs, in press 2016. Observing eruptions of gas-rich, compressible magmas from space. Nature Communications.

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