Insights into eruption activity between recent caldera-forming eruptions at Campi Flegrei caldera (southern Italy): A Detailed Tephrostratigraphic Record from Monte di Procida.

Campi Flegrei caldera (CFc) is one of the most hazardous volcanic systems in Europe, with over 1.2 million people in Naples living within 10 km of the active volcano and the neighbouring volcanoes of Ischia, Procida, and Somma-Vesuvius^[1]. Constraining the explosive eruptive history of CFc is critical for understanding future volcanic hazards. Over the past 40 kyr, three caldera-forming eruptions have occurred at CFc: the Campanian Ignimbrite (CI; 40 ka^[2]), the Masseria del Monte Tuff (MdMT; 29.3 ka^[3]) and the Neapolitan Yellow Tuff (NYT; 14.9 ka^[4]). Whilst these major events are well characterised, smaller eruptions between them remain poorly constrained in magnitude and time despite representing key phases in the magmatic evolution of CFc. Few proximal sections preserve a detailed record of eruption deposits from the interval between the CI and NYT.

 

We present new detailed field and glass geochemical data from Monte di Procida, southwest of CFc, which records 21 tephra units, including the CI and NYT. This represents the most complete CI–NYT sequence identified to date. Three main CFc compositional subgroups are recognised: (i) a dominant NYT-like trachytic melt (~60 wt.% SiO₂) with limited variability, (ii) a more evolved trachytic subgroup (~64 wt.% SiO₂), and (iii) a trachybasaltic composition (~55 wt.% SiO₂). The section also contains distinct Solchiaro (~23 ka^[5]) tephras from Procida, separated by an Ischia-derived ash, evidencing contemporaneous activity during this interval across the Campanian Volcanic Zone. These data reveal that at least 15 of the eruption deposits are from CFc, indicating a higher pre-NYT eruptive tempo than previously recognised.

 

The Monte di Procida record reveals greater activity with 11 eruptions in the 9 kyr preceding the NYT eruption, suggesting frequent activity in the build-up to the NYT caldera-forming eruption. Inter-eruption glass compositions show similar chemical signatures with limited variability in major and trace elements, complicating the use of tephras from this record in wider regional correlations.

 

References:

1. Meredith et al. (2025) Nat. Hazards Earth Syst. Sci. 25: 2731-2749.

2. Giaccio et al. (2017) Sci. Rep. 7: 45940.

3. Albert et al. (2019) Geology. 47: 595-599.

4. Deino et al. (2004) JVGR. 133: 157-170.

5. Morabito et al. (2014) Glob. Plan. Change 123: 121-138.