Phys.org October 12, 2021
Volcano eruption style is thought to be strongly controlled by fast conduit processes, limiting our ability for prediction. To understand if the eruptive behaviour is predetermined by the state of the magma in the subvolcanic reservoir an international team of researchers (Switzerland, USA – Brown University) analysed the pre-eruptive storage conditions of 245 units from volcanoes around the world. They showed that pre-eruptive crystallinity, dissolved water content and the presence of exsolved volatiles in the chamber exert a primary control on eruptive styles. Magmas erupt explosively over a well-defined range in dissolved water content (~4–5.5 wt%) and crystallinity (less than 30 vol%). All other conditions, such as higher crystallinity, dissolved water contents below 3.5 wt% and, counterintuitively, in excess of 5.5 wt%, favour effusive activity. Between these ranges, there is a narrow field of transitional storage properties that do not discriminate between eruptive styles, and where the conduit exerts the main control on eruptive behaviour. Their findings suggest that better estimates of crystallinity and water content in subvolcanic chambers are key to forecasting eruptive style…read more. TECHNICAL ARTICLEÂ
The distribution of crystallinity and storage temperatures with eruptive behaviours. Credit: Nature Geoscience volume 14, pages781–786 (2021)Â