Uncovering the long-term evolution and pattern of ground deformation in active calderas: reconciling Holocene volcano-tectonic processes and volcanism at Campi Flegrei (southern Italy)

Calderas often host monogenetic volcanism during their post-collapse evolution, and this is usually coupled with ground deformation episodes that lead to a resurgence in the long term. Understanding the non-trivial relationships between erupted volumes and resurgence deformation is critical to properly facing volcanic unrest at densely populated volcanoes. This sense of urgency is strongly felt for the restless Campi Flegrei caldera (southern Italy), which is experiencing elevated volcanic unrest with heightened levels of seismicity, geochemical anomalies and, not least, ground uplift. In this work, we reassess the state-of-the-art understanding of ground uplift at Campi Flegrei, addressing the affirmed models and interpretations of the observables at different time scales. As an element of novelty in the literature, we provide a quantitative estimation of the deformation shape and amount of ground uplift and subsidence, constraining the mode of resurgence and individuating deformation anomalies. This allowed us to comprehensively reconstruct the history of deformation throughout the Holocene. We also constrain the timing of volcano-tectonic fault activity and the reactivation of caldera structures that accommodate the deformation. On these grounds, in combination with the reassessment of spatial and temporal patterns of volcanism, we provide a robust interpretative model explaining the relationship between ground deformation and eruptions, including its significance in terms of volcanic hazards. Our results challenge the existing models linking ground deformation and eruptions and should foster constructive discussion about the volcano deformation dynamics at Campi Flegrei.