Operational Short-term Volcanic Hazard Analysis

Probabilistic Volcanic Hazard Assessment (PVHA) is the most complete scientific contribution for planning rational strategies aimed at mitigating the risk posed by volcanic activity at different time scales. The definition of the space–time window for PVHA is related to the kind of risk mitigation actions that are under consideration. During volcanic unrest episodes or eruptions, short-term PVHA is essential for crisis management, since tephra may heavily affect building stability, public health, transportations and evacuation routes (airports, trains, road traffic), and lifelines (electric power supply). In this study, we propose a new methodology for the short-term PVHA based on the Bayesian Event Tree model, in which measures from the monitoring system are used to routinely update the probabilities of ash fall loading in the surroundings of the volcano. As an example, we apply this procedure to the 1982–1984 volcanic unrest at Campi Flegrei, Italy.