Ongoing unrest at Campi Flegrei, Italy: clues from the antecrystic records
- 1University of Geneva, Earth Sciences, Switzerland (charline.lormand@unige.ch)
- 2Dipartimento di Scienze, Università degli Studi Roma Tre, Roma, Italy
- 3Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy
The largest deformation since the start of the ongoing unrest at Campi Flegrei caldera, Italy, was recorded in 2023 with an average uplift rate of 17 cm/year [1]. This coincides with the exponential increase of seismic events since 2017 by a factor of 32 (i.e., 6065 events in 2023 versus 3181 in 2022, 2232 in 2021, 1520 in 2020, 799 in 2019, etc.). Such observations raise questions regarding the origin and the future of the ongoing unrest especially in determining if the underlying cause involves ascent of magmatic fluids only or if magma is also involved. To this end, a forensic approach focusing on the characterisation of crystal cargoes from past eruptions help understanding of the conditions and pre-eruptive processes that occur within magmatic plumbing system prior to eruptions of different styles and comparing these possible scenarios with the current unrest.
Juvenile clasts found in the base layer from deposits of past eruptions (e.g., Agnano-Monte Spina, Solfatara, Averno, Astroni, Monte Nuovo) of different eruption styles and size were collected. The 1538 eruption of Monte Nuovo is the ideal benchmark to link the petrological evidence to the precursory deformation documented, whereas the historical eruptions selected allow for consideration of a wider range of eruption scenarios. We will present machine learning thermobarometric data and chemical patterns inferred by clustering techniques used to constrain the temperature-pressure paths of the magma and to identify possible systematics during the period of magma migration to the surface preceding the eruption. Ultimately, we aim to link the petrological signatures conveyed by antecrysts with the deformation triggered during magma intrusion and expansion of volatiles upon ascent.
Reference: [1] INGV. Bollettini di sorveglianza dei vulcani campani. http://www.ov.ingv.it/ov/bollettini-campi-flegrei/ (2016-2023).
How to cite: Lormand, C., Caricchi, L., Giordano, G., and Isaia, R.: Ongoing unrest at Campi Flegrei, Italy: clues from the antecrystic records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20705, https://doi.org/10.5194/egusphere-egu24-20705, 2024.
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There was a mistake with the legend of the clusters which has now been fixed. Sorry about the confusion! I even confused myself for a moment.
We have a Cr-Mg-rich magma which is recorded by cpx at HP and HT and we have the other endmember at shallower depths (4-6 km), which is Si-Fe-rich suggesting a more evolved and thermally mature system. Then, we have two intermediate clusters. With time, the LP and LT Si-Fe-rich magma seems to be more tapped by cores, mantles and rims of crystals, which is where we see most of the current deformation. Apart from Triflisco which only recorded the HP and HT reservoir, all the eruptions have clinopyroxenes recording the range of pressures and temperatures. However, it seems that the shallow Si-Fe rich reservoir is more frequently tapped with time, especially in the core of cpx. However, these more recent eruptions still sample the deeper Cr-Mg-rich reservoir, even in the core of the crystals. This implies that there is magma migration from the deep to the shallow reservoir, and there is no evidence of rapid ascent, except for the older eruptions which recorded syn-eruption crystallisation (Vitulazio) and rapid ascent from the HT and HP reservoir (Triflisco). The current unrest and associated deformation at 4 km may reflect magma accummulation from the deep reservoir to the shallow reservoir. Spoiler alert: preliminary results of thermal modelling show that the volume calculated from the current deformation cannot be explained by volatile only. Plus, there is no obvious change of gas volume and chemistry during the frequent earthquake swarms.