Assessing volcanic hazard at Campi Flegrei caldera (Italy) with uncertainty quantification

Abstract

Campi Flegrei (CF) is an example of an active, densely populated, caldera with very high risks associated with the occurrence of explosive eruptions. In particular, mapping of pyroclastic density currents (PDCs) hazard is challenging due to the large uncertainty on future vent location and eruption scale as well as the complex dynamics of flows over caldera topography. In this presentation we show how volcanological datasets of different type, mathematical modelling and expert elicitation techniques have been used to produce base-rate probabilistic vent opening and PDC inundation maps. The analysis particularly focused on the reconstruction of the location of past eruptive vents and it allowed the incorporation of additional volcanological datasets, such as the distribution of faults and surface fractures assumed to be representative of areas of crustal weaknesses in the caldera. One key objective was to directly incorporate some of the main sources of epistemic uncertainty relating to an understanding of the volcanic system. We used a formal and structured expert elicitation procedure to quantify uncertainties for the main parameters and evaluate the outcomes through different expert weighting models. A set of probabilistic PDC inundation hazard maps were then produced by the Monte Carlo approach based on a simplified inundation model and incorporating uncertainties on future vent location and event scale.