The exsolution and escape of volatiles drives both effusive and explosive eruptions. Exsolution starts with nucleation and growth of bubbles and fractures, and the permeability of the magmatic foam evolves. These mechanisms lead to both the outgassing and regassing of volatiles as magma encounters different pressures and temperatures, prior to, during and after volcanic eruptions.
Degassing mechanisms have been described in experiments, observed in natural samples and geophysical signals and modeled. While new techniques such as tomographic imaging and spectroscopic analysis allow insights into microscopic scales of volatile pathways and distributions, geophysical data and numerical models can help us to understand the impact of such observations on the complex system of processes of volcanic degassing during magma ascent. In this session we invite contributions from all disciplines of earth- and material sciences to one of the most fundamental aspects of volcanic eruptions: magma degassing.