This week’s planned speaker, Angus Fotherby, was unwell and could not give the first seminar of the new year. We wish him a quick recovery and hope he will be able to return before the end of term to tell us about Chromium contamination and remediation in India.
Today, professor Andy Woods discussed a number of multiphase flows occurring in volcanic systems. As the molten magma in a magma chamber cools down, solid crystals are formed. The crystals tend to be relatively dense and have a low water content: hence, the water content in the fluid surrounding them increases, until it exceeds the saturation level, leading to the formation of bubbles. The magma chamber then contains a three-phase mixture of magma, gas and crystals, which is compressible and viscous.
During his talk, Andy discussed the effect of bubbles and crystals separating from this mixture inside the magma chamber, and showed how different magmas may be erupted at different times during an eruption, following the convective overturn of the fluid in the chamber. Finally, Andy reviewed some data collected during a number of recent eruptions, and discussed the more complex behaviours of volcanoes with multiple magma chambers.