Bevilacqua A., A. Neri, A. Bertagnini, L. Corna, M. de’ Michieli Vitturi, A. Di Roberto,  F. Di Traglia, F. Flandoli, Z. Geddo, M. Pompilio, A. Tadini, (2026).
Journal of Geophysical Research: Solid Earth, 131, e2025JB032571. https://doi.org/10.1029/2025JB032571

Abstract

This study presents a new method to assess the hazard of deposit-derived pyroclastic density currents (PDC), a critical threat on volcanic islands and on populated slopes of active volcanoes, considering the exemplary case study of Stromboli (Italy). Events that occurred at Stromboli in 1930 and 1944 demonstrate the destructive potential of these flows and the need to assess their hazard. In particular, this work provides first estimates of invasion probability over future decades in case of events similar to those of last century. The analysis of topographic basins, alongside the use of a numerical flow model tested with the well-documented 1930 event, allowed the identification of six main drainage basins with significant impact potential. Among the most exposed basins, we estimated conditional invasion probabilities up to 28% at 50 m a.s.l.. Using a new temporal model that links the frequency of Strombolian paroxysms to PDC occurrence, we estimated a mean probability of at least one PDC occurrence outside Sciara del Fuoco of ≈9% over the next 10 years and 49% over 50 years. When combined with spatial estimates, mean invasion probabilities of up to 4% in inhabited areas of the three more exposed basins over the next decade were computed, which increased sevenfold over 50 years. In the other inhabited valleys considered, the invasion probabilities are about half of these values. Our findings highlight the remarkable, although significantly uncertain, risk associated with deposit-derived PDCs at Stromboli, and illustrate a useful novel approach to map such hazard at similar volcanic systems.