Large destructive effusive eruptions are often fed by lavas able to run for tens of kilometres before cooling and increase in viscosity leads to a halting. Their length is driven by different factors among which viscosity governed by the syn-eruptive crystallization and gas loss. Since both processes cannot be observed in natural flowing lavas, their study must be conducted through laboratory experiments. This project aims to investigate the crystallization and degassing of silicate melts at subaerial conditions representative of some of the major volcanic systems of the world. 

Targeted field surveys on specific lavas will be conducted to obtain a high-precision mapping and thus volume estimate of the erupted products, especially in volcanic contexts were this information is not accessible through literature or is subject to high degree of uncertainty. 

Representative lava samples with mafic to silicic compositions will be selected and characterized with geochemical and petrographic techniques. The crystallization timing and sequence will be then investigated with high temperature 4D X-ray computed microtomography experiments to determine in real timethe growth rate of the crystalline phases at variable cooling rates and volatiles content. The evolution of lava viscosity will be modelled using well-established methods existing in literature. 

Results will improve our knowledge of the degassing-coolingcrystallization process of lava flows and will allow to reconstruct the rheology evolution during the lava advancing. Results will answer to the following questions: what is the crystallization sequence of lava flows at subaerial conditions? What is the link between cooling rates, crystal composition and textures? What are the bubble nucleation and growth rate? 

The constrains on crystallization dynamics of lavas will help in future forecasting of lava flow length during large effusive eruptions, with strong impact on the hazard assessment in volcanic areas characterized by high risk of lava flow invasion.