Role of volatiles in highly explosive basaltic eruptions

Water and carbon dioxide are the most abundant volatile components in terrestrial magmas. As they exsolve into magmatic vapor, they promote magma buoyancy, accelerating ascent and modulating eruptive dynamics. This study uses a conduit model for basaltic eruptions (upper 6 km) to show that mass eruption rate is unaffected by CO2 content, while increasing H2O up to 10 wt.% increases eruption rate by an order of magnitude. Only with external CO2 injection into the magma reservoir does pressurization strongly increase eruption rate. Ascent velocity and fragmentation depth are strongly affected by pre-eruptive volatile contents, linking volatile content to eruptive style.

Giuseppe La Spina, Fabio Arzilli, Mike R. Burton, Margherita Polacci, Amanda B. Clarke