Pre-eruptive processes and timescales of highly explosive and Strombolian eruptions at Campi Flegrei: The case studies of Agnano Monte-Spina and Fondo Riccio

The Campi Flegrei caldera in southern Italy represents one of the most hazardous volcanic systems on Earth, owing to its potential for explosive eruptions and its proximity to a densely populated metropolitan area. Volcanism at Campi Flegrei spans a spectrum of eruptive styles, from effusive dome-building events to high-intensity explosive eruptions, and is dominated by trachytic to trachy-phonolitic magmas, with subordinate latitic compositions. While trachytic eruptions are typically associated with high explosivity, latitic magmas are less frequent and generally produce lower-energy eruptions. Constraining the pre-eruptive processes and magma residence timescales prior to eruption is critical for assessing hazards in this high-risk volcanic setting. However, the difference between pre-eruptive processes and timescales prior to highly explosive trachytic and less explosive latitic eruptions are poorly constrained. Here we integrate chemical analyses of natural samples, geothermometric constraints, thermodynamic simulations and crystallisation experiments (cooling and decompression) to constrain the processes, conditions, and timescales that lead to highly explosive and Strombolian eruptions of trachytic and latitic magmas at Campi Flegrei.