Principles of volcanic risk metrics: Theory and the case study of Mount Vesuvius and Campi Flegrei, Italy

Abstract

[1] Despite volcanic risk having been defined quantitatively more than 30 years ago, this risk has been managed without being effectively measured. The recent substantial progress in quantifying eruption probability paves the way for a new era of rational science-based volcano risk management, based on what may be termed ''volcanic risk metrics'' (VRM). In this paper, we propose the basic principles of VRM, based on coupling probabilistic volcanic hazard assessment and eruption forecasting with cost-benefit analysis. The VRM strategy has the potential to rationalize decision making across a broad spectrum of volcanological questions. When should the call for evacuation be made? What early preparations should be made for a volcano crisis? Is it worthwhile waiting longer? What areas should be covered by an emergency plan? During unrest, what areas of a large volcanic field or caldera should be evacuated, and when? The VRM strategy has the paramount advantage of providing a set of quantitative and transparent rules that can be established well in advance of a crisis, optimizing and clarifying decision-making procedures. It enables volcanologists to apply all their scientific knowledge and observational information to assist authorities in quantifying the positive and negative risk implications of any decision.

The Effects of Vent Location, Event Scale, and Time Forecasts on Pyroclastic Density Current Hazard Maps at Campi Flegrei Caldera (Italy)

“…Nevertheless, such achievement product is necessary for urban planning and risk reduction on the territory. In particular, a significant improvement of the risk mitigation strategies is enabled by the quantitative combination of the probability distributions for the spatial location of the eruptive vent originating the PDC, the size of the flow, and the temporal estimates for such expected event in the future (see Woo, 1999;Marzocchi and Woo, 2009;Rougier et al, 2013;Wadge and Aspinall, 2014). This accomplishment is the main purpose of this research study.…”

Rational volcanic hazard forecasts and the use of volcanic alert levels

“…More recently, the approach has been further developed by Bebbington and Zitikis (2016) to place it into a time-dependent framework which considers the time windows between effective changes in the eruption probability, the call of an evacuation and its completion, further evolution (either increasing or decreasing) in eruption probabilities, the actual eruption occurrence, and citizens' dislocation and their return to the affected areas. In a retrospective application to the 1631 sub-Plinian eruption of Vesuvius, they found that the eruption probability value justifying the evacuation call turns out to be 13% lower than for the "static" approach by Marzocchi and Woo (2009). Translated into the reconstructed time evolution of the eruption probability, that difference would have anticipated an evacuation call by six days.…”

A fast GIS-based risk assessment for tephra fallout: the example of Cotopaxi volcano, Ecuador-Part II: vulnerability and risk assessment

“…50 %) make the evaluation of the exposure clearer to decision-makers and the identification of the potential losses faster for governments. The acceptable levels of risk required to compile isomass maps are of complex identification (Marzocchi and Woo 2009;Villagrán de León 2006).…”