Dynamics of Explosive Submarine Explosions

Deep submarine deposits from explosive or mildly explosive eruptions of viscous volatile bearing magma have been identified at numerous sites, the 2012 eruption of Havre volcano is a well documented example (Carey 2018; Allen and McPhie, 2009). Observations have indicated the presence and transport of pumice rafts on the sea surface as well as large pumice deposits on the sea floor (Jutzeler, 2014). The phenomena associated with these eruptions are just becoming understood from field observations and the topic is ripe for a new generation of models and laboratory experiments to quantify the different processes and provide new interpretations for the different classes of deposit.

The dynamics of the transport and dispersal of pumice and smaller vesicular fragments of hot erupted material through the water column involve fascinating flow processes distinct from their sub-aerial counterparts. In particular, the pumice fragments may become waterlogged leading to a change in their buoyancy and this can have a material impact on the evolution and transport processes in the two-phase water-pumice flows, with dense particle laden flows on the sea floor and two-phase fountains and plumes.

The project will involve new quantitative modelling and novel laboratory experiments to explore the dynamics of submarine eruptions and contrast and compare these with the dynamics of sub-areal eruptions, for which many of the processes have been modelled and interpreted from field observations and analogue laboratory models. Given the significant number of submarine eruption deposits in the geological record, understanding the processes controlling the fate of the solid and gas emitted during a submarine eruption is a fundamental and important emerging area in volcanology.

The student will build models to explore the dynamics of pumice-water plumes and gravity currents (cf Mingotti and Woods, 2015), in parallel with building models to explore the processes of water-logging of the pumice particles in these flows. The student will use these models to make predictions of the different modes of activity of material erupted in a sub-marine eruption. The model predictions will be compared or tested with field observations, where possible, or used to help provide new interpretations of field data as reported from field studies of the submarine deposits, including the recent Havre eruption. This will lead to new insights into the dispersal processes for pumice and other solid material associated with these eruptions.