The mildly explosive to caldera-forming transition at Colli Albani volcano

The effusive-explosive transition in mafic systems is a complex and still largely debated phenomenon in volcanology. Understanding this transition is crucial for hazard assessment and risk mitigation since explosive eruptions can pose significant dangers to nearby populations and infrastructure. In this study, we investigate this transition focusing on a natural study case: the Colli Albani volcano. The Colli Albani is an ultrapotassic caldera complex located 30 km SE of Rome. This volcano has exhibited a wide range of eruptive behaviours throughout its history, ranging from effusive activity to highly explosive eruptions (Giordano & CARG Team, 2010). Here, two main eruptive sequences were selected: The Fontana Centogocce formation (SLV) and the Villa Senni ignimbrites (VSN). SLV represents a period of effusive to mild-explosive eruptions and preceded the emplacement of the 50 km³ Villa Senni ignimbrites (VSN), which represent the last caldera-forming event of the volcano.

This study integrates field and petrographic observations, clinopyroxene textural and chemistry analyses and machine learning thermobarometry to understand and constrain the variables influencing the shift from mildly-explosive to caldera-forming eruptions. We present a reconstruction of the volcanic plumbing system's architecture and offer insights into how the system rebuilds in its interim after one of these large events.

 

Giordano, G., & CARG Team. (2010). Stratigraphy, volcano tectonics and evolution of the Colli Albani volcanic field. In: Funiciello, R., Giordano. G. (eds). The Colli Albani volcano. Special Publications of IAVCEI, vol 3, Geological Society, London, 43-98.