Combining magma flow models and deformation measurements to understand magma ascent at silicic volcanoes

Panorama DTP PhD project proposal

Combining magma flow models and deformation measurements to understand magma ascent at silicic volcanoes

Prof Jurgen Neuberg & Dr Susanna Ebmeier
J.Neuberg@leeds.ac.uk

 

Volcanic deformation can be caused by a broad range of processes related to the movement and evolution of magma. The type of processes detectable depends on the temporal and spatial resolution of the  measurement method.   Satellite radar  measurements have so far most often captured reservoir-related processes, with a modal source depth of ~ 5km (Ebmeier et al., 2018). GPS or tilt measurements made near the volcanic conduit  are  more likely to capture transient signals associated with magma transport, but have been often modelled and interpreted as inflation or deflation of a shallow magma reservoir (Hautmann et al., 2009). More recently, shear stress has been identified as an additional source of deformation (Neuberg et al.2018; Marsden et al. 2019) which takes magma flow in shallow, silicic conduit systems into account. Hence, deformation models can now describe a range of processes between the pressurization of deep reservoirs and shallow magma ascent  . So far, most models treat magma as a liquid,   with a volume change that can account for surface displacements.

Fig1 Rock-fall activity by night at Soufriere Hills volcano on Montserrat, West Indies, which showed over many years cyclic activity of magma extrusion and pauses, reflected in a cyclic deformation pattern.

 

In this project we intend to combine deformation models and magma flow models to incorporate three-phase fluid flow (melt, crystals, volatiles), pressurization through crystallization (second boiling), degassing and outgassing, and thermal boundary layers into models of magmatic processes (Marsden et al., 2019). These magmatic processes affect the possible range of viscosities at different depths, as well as the range of pressures that can act at reservoir depth and shallow conduit level.

By combining the modelling of shallow magma flow and magmatic processes with the deformation patterns  originating at reservoir depths , this project will gain new insights into the large variety of cyclic behaviours of silicic volcanoes.  Examples of volcanoes with well-documented cyclic behaviour and deformation on multiple spatial scales include Soufriere Hills in Montserrat, West Indies and Tungurahua, Ecuador. . For both volcanoes we have access to extensive data sets which will form the data base for the investigation, but further data sets such as seismicity and petrological data will be taken into account as well.

Fig 2. TerraSAR-X spotlight data for Soufrière Hills volcano provided by GFZ Potsdam. Note the different scales; the right panel shows mainly subsidence of volcanic deposits near the volcano (blue) while an area in the NW of the data coverage indicates uplift (red)

PhD Training

According to background and specific research interests, the student will be provided with training in analytical and numerical modeling techniques, and will use and further develop tools in volcano deformation analysis, numerical magma flow modelling, and deformation models. Volcanic monitoring experience will be gained at Soufriere Hills volcano, on the Caribbean Island of Montserrat at the volcano observatory (MVO) as well as on Tungurahua and Cotopaxi with the Geophysical Institute (IG) in Quito, Ecuador. We have maintained with both institutions very good links over many years and have an existing Memorandum of Understanding controlling data exchange and co-operation. Visits to both institutions will be necessary to implement forecasting tools at these observatories in co-operation with observatory staff. The student will be supervised by Prof Jurgen Neuberg and Dr Susanna Ebmeier, and will be part of a colourful and multi-disciplinary group of scientists in the UK and abroad, due to the multi-national co-operation and research contacts of the Volcano Study Group at Leeds.

Student Profile

The student should have a background in a quantitative science, an interest in volcanology and  model development.  They should also have an enthusiasm for overseas travel and international collaboration.

Impact of research

Living safely with active volcanoes has become a pressing issue for millions of people and scientist need to be able not only to predict a first onset of an eruption but also to identify the slightest change during volcanic activity in order to advise local authorities and civil defense agencies. The outcomes of this project will provide a major contribution to this aim, and through direct contact with relevant volcano observatories will provide new insights into deformation modelling.

References

Ebmeier SK, Andrews BJ, Araya MC, Arnold DWD, Biggs J, Cooper C, Cottrell E, Furtney M, Hickey J, Jay J, Lloyd R, Parker AL, Pritchard ME, Robertson E, Venzke E, Williamson JL. 2018. Synthesis of global satellite observations of magmatic and volcanic deformation: implications for volcano monitoring & the lateral extent of magmatic domains. Journal of Applied Volcanology. 7, 2

Hautmann, S., Gottsmann, J., Sparks, R.S.J., Costa, A., Melnik, O., and Voight, B. 2009. Modelling ground deformation caused by oscillating overpressure in a dyke conduit at Soufriere Hills Volcano, Montserrat: Tectonophysics, v. 471, p. 87–95, doi:10.1016/j.tecto.2008.10.021.

Marsden LH, Neuberg J, Thomas M, Mothes P, Ruiz M. 2019. Combining magma flow and deformation modelling to explain observed changes in tilt. Front. Earth Sci., https://doi.org/10.3389/feart.2019.00219

Neuberg JW, Collinson ASD, Mothes PA, Ruiz MC, Aguaiza S. 2018. Understanding cyclic seismicity and ground deformation patterns at volcanoes: intriguing lessons from Tungurahua volcano, Ecuador. Earth and Planetary Science Letters. 482, pp. 193-200.