Abstract
AbstractIn this study, we combine reconstructions of volcanological data sets and inputs from a structured expert judgment to produce a first long‐term probability map for vent opening location for the next Plinian or sub‐Plinian eruption of Somma‐Vesuvio. In the past, the volcano has exhibited significant spatial variability in vent location; this can exert a significant control on where hazards materialize (particularly of pyroclastic density currents). The new vent opening probability mapping has been performed through (i) development of spatial probability density maps with Gaussian kernel functions for different data sets and (ii) weighted linear combination of these spatial density maps. The epistemic uncertainties affecting these data sets were quantified explicitly with expert judgments and implemented following a doubly stochastic approach. Various elicitation pooling metrics and subgroupings of experts and target questions were tested to evaluate the robustness of outcomes. Our findings indicate that (a) Somma‐Vesuvio vent opening probabilities are distributed inside the whole caldera, with a peak corresponding to the area of the present crater, but with more than 50% probability that the next vent could open elsewhere within the caldera; (b) there is a mean probability of about 30% that the next vent will open west of the present edifice; (c) there is a mean probability of about 9.5% that the next medium‐large eruption will enlarge the present Somma‐Vesuvio caldera, and (d) there is a nonnegligible probability (mean value of 6–10%) that the next Plinian or sub‐Plinian eruption will have its initial vent opening outside the present Somma‐Vesuvio caldera.
Highlights
Somma-Vesuvio (SV) is one of the most studied and high-risk volcanoes in the world
Our findings indicate that (a) Somma-Vesuvio vent opening probabilities are distributed inside the whole caldera, with a peak corresponding to the area of the present crater, but with more than 50% probability that the vent could open elsewhere within the caldera; (b) there is a mean probability of about 30% that the vent will open west of the present edifice; (c) there is a mean probability of about 9.5% that the medium-large eruption will enlarge the present Somma-Vesuvio caldera, and (d) there is a nonnegligible probability that the Plinian or sub-Plinian eruption will have its initial vent opening outside the present Somma-Vesuvio caldera
With the spatial density maps described above, we applied the structured expert elicitation techniques described in section 2 and Appendix B to ascribe a weight to each map and combine them into a joint probability map
Summary
Somma-Vesuvio (SV) is one of the most studied and high-risk volcanoes in the world. Its eruptive history has been investigated through many studies since the first eyewitness account of the famous A.D. 79 Pompeii eruption by Plinius the Younger [e.g., Sigurdsson et al, 1985; Cioni et al, 1992, 2008]. It is established that, especially over the last 2 ka, many volcanic vents opened outside the boundary of the present SV caldera [Santacroce and Sbrana, 2003; Principe et al, 2013; Tadini et al, 2017], mainly on the western and southern flanks [Acocella et al, 2006; Paolillo et al, 2016].
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