Multiple natural hazards at volcanic islands: a review for the Ischia volcano (Italy)

Abstract

Volcanic islands pose several major types of natural hazards, often interconnected and concentrated in relatively small areas. The quantification of these hazards must be framed from a multi-hazard perspective whilst building on existing single-hazard analyses. Ischia is a densely inhabited volcanic island with a long eruptive history lasting more than 150 ka (last in 1302 AD) characterized by the significant asymmetric resurgence of a caldera block. Here, we review the state-of-art of the natural hazards of Ischia, aiming at building a solid base for future holistic multihazard quantifications. We frame our analysis in three steps: i) review of geological, historical and current activity; ii) review of available hazard models and analyses; iii) development of an interpretative framework for the interdependent hazards. The results highlight that volcanic activity has been quite intense and many volcanorelated hazardous phenomena have affected the island including in very recent times, both for eruptive (phreatic or magmatic eruptions) and non-eruptive (earthquakes, landslides, and tsunamis) phenomena. The effects of some of them (e.g. tsunamis, tephra) are also relevant beyond the island territory. Quantitative hazard assessments are almost absent and should be developed in the future considering the evident interconnections between hazards. To this end, we propose a conceptual interpretative multi-hazard framework that highlights the fundamental role played by the resurgent block in controlling and connecting the different hazards, in terms of both spatial distribution of the sources and temporal clustering.

Multisource Bayesian Probabilistic Tsunami Hazard Analysis for the Gulf of Naples (Italy)

“…Among the many different potential volcanic sources, only the Somma‐Vesuvius eruptions have left geological evidence of tsunamigenesis reaching the Gulf of Naples due to dense entering the sea (Tinti et al, ). Other potential volcanic sources include the underwater explosions at the Campi Flegrei (Paris et al, ); lahar flows entering the sea (Paris et al, ; Tierz et al, ); potential submarine volcanic activity from other volcanoes such as Marsili, Palinuro, and Vavilov (Caratori Tontini et al, ); and the insular volcanoes (as Ischia, Stromboli, Salina, and Vulcano) (Paparo & Tinti, ; Selva et al, ).…”

“…The tsunamis observed in the last 2,000 years in the Gulf of Naples were caused mainly by earthquakes and volcanic activity. The Ischia debris avalanche event was antecedent to the time interval covered by the Italian Tsunami Catalog, and, in any case, there is no evidence of Ischia avalanches that generated tsunamis in the area (Selva et al, ). Also, the tsunami intensity and the reliability are indicated in the catalog.…”

“…The consequences of an Ischia debris avalanche were explored as single scenarios by Tinti et al () and Paparo and Tinti (). A few studies for long‐ and short‐term tsunami hazard were carried out in the region including both submarine mass failures and submarine earthquakes (Grezio et al, ; Selva et al, ).…”

Analysis and Classification of Natural and Human-Induced Ground Deformations at Regional Scale (Campania, Italy) Detected by Satellite Synthetic-Aperture Radar Interferometry Archive Datasets

“…Ischia ground deformation pattern ( Figure 11) cannot be explained by a typical volcanic source [70,71]. The Ischia deformation pattern is related to a combination of endogenous and exogenous processes that include deflation of the island related to the depressurization of the local hydrothermal system, fault activity and landslides due to gravity instability on slopes [5,35,36], and to the coupling effects of crust rheology and the gravitational loading of the volcano [70].…”

Geochemical and Sr–Nd isotopic features of the Zaro volcanic complex: insights on the magmatic processes triggering a small-scale prehistoric eruption at Ischia island (south Italy)

“…Nevertheless, due to the large number of eruptive episodes (at least 47), the change in chemical and isotopic composition of magma with respect to the previous periods of activity (Civetta et al 1991;Casalini et al 2017), the concomitance of resurgence and explosive activity (e.g. de Vita et al 2006), the last 10 ka is the reference time window for probabilistic volcanic hazard assessment (Selva et al 2019). Therefore, improving the 1 3…”