No single model for super-sized eruptions and their magma bodies

The largest explosive volcanic eruptions on Earth (‘supereruptions’) generate widespread ash-fall blankets and voluminous ignimbrites with accompanying caldera collapse. However, the mechanisms of generation, storage and evacuation of the parental silicic magma bodies remain controversial. In this Review, we synthesise field and laboratory evidence from Quaternary supereruptions to illustrate the great diversity in these phenomena. Despite their size, some supereruptions started mildly over weeks to months before escalating into climactic activity, whereas others went into vigorous activity immediately. Some eruptions occupied days or weeks, and others were prolonged over decades. Some were sourced from single bodies of magma, and others from multiple magma bodies that were simultaneously or sequentially tapped. In all cases the crystal-richer, deeper roots (>10 km) of the magmatic systems had lifetimes of tens to hundreds of thousands of years or more. In contrast, the erupted magmas were assembled at shallower depths (4-10 km) on shorter timescales, sometimes only centuries. Geological knowledge of past events, combined with modern geophysical techniques, demonstrates how large silicic caldera volcanoes (with past supereruptions) operate today. Future research is needed particularly on the processes behind modern volcanic unrest and the signals that might herald an impending eruption, regardless of size, at such volcanoes.