Tidally faced melting, magmatic segregation, and planetary evolution of Jupiter's moon Io. Theory and computational models

Io is a satellite of Jupiter and among the most volcanically active bodies in the solar system. The internal dynamics of the planet are not yet well understood. The aim of this project is to develop and adapt mathematical theory based on conservation principles, obtain solutions using sophisticated numerical models, and based on the results, interpret surficial observations of the planet in terms of the dynamic processes happening at depth.

Io shows intense volcanic activity, high-temperature lavas (1600-1700 K), and an average surface heat flux of 2.5 W m-2 (30x Earth value) (see review by Schubert et al. 2004). The supply of heat required to sustain such conditions is believed to come from tidal dissipation caused by orbital resonance between Io, Europa and Ganymede. This tidal heating is thought to lead to partial melting of the asthenosphere up to melt fractions of ~20%. These large melt fractions are higher than are thought possible on Earth and are likely permitted by the low gravity of Io, preventing compaction from being effective.

Many questions surround the sub-surface relationships of Io's volcanos. At low latitudes volcanos appear to be uniformly distributed, maximising their separation from each other (Hamilton et al, 2013). This would imply that they are somehow interacting at depth, but this relationship is however not observed at higher latitudes. Computer models coupling tidal heating distribution within the body to melt formation and migration could help probe these intriguing observations. This would attempt to look at whether melt production beneath individual features was sufficient to support the volcanic output of the feature, and if not, how large a catchment area would be needed. The models could also help answer other mysteries surrounding Ionian volcanism, such as the apparently increased volcanism at low latitudes; the local correlation of mountains and volcanic features but lack of global correlation; potential temporal clustering of large volcanic 'outbursts'; and physical dynamics of 'top down tectonism'.

Work up to this point surrounding Io has generally not coupled tidal heating, melt formation, and melt extraction with full thermo-dynamics and two-phase flow. Rather they have simplified one or more of these areas, in particular tending to simplify two-phase flow. This work would would look to tie these together along with new rheological considerations and tidal heating distribution calculations, revealed by recent papers (in particular Bierson and Nimmo, 2016).

This project falls within the 'Astronomy and Space Science' research area of the STFC remit.