Volcanic eruptions can have significant impact on life, infrastructure, commerce and climate. Erupting magma is a mixture of hot rock fragments (formerly magma), such as volcanic ash, and volcanic gases that are transported to surface as bubbles within the erupting magma. Bubbles may both, confine magmatic gases potentially resulting in large excess gas pressures, or they may facilitate syneruptive gas loss by forming permeable networks during bubble coalescence. Consequently, bubbles play a crucial role in a feedback with magma ascent rate and affect the style and explosive intensity of eruptions.
This project will further our quantitative understanding of the various processes that affect bubbles and magmatic gases during volcanic eruptions. We will develop a new bubble-scale numerical model for bubble growth, deformation and coalescence. The model will be calibrated to laboratory experiments that are specifically designed to facilitate the integration of empirical data. The bubble-scale model will then be coupled with a multiphase conduit flow model to address problems such as (1) the spatiotemporal evolution of gas pressure in an erupting magma with a polydisperse bubble size distribution; (2) the implications for magma fragmentation; (3) bubble coalescence during shear deformation of the erupting magma; (4) open-system gas loss by permeable flow through coalesced bubbles; and (5) shear localization within the ascending magma.
