PVHA methodologies provide a framework for assessing the likelihood of a given measure of intensity of different volcanic phenomena, such as tephra loading on the ground, airborne ash concentration, pyroclastic flows, etc., being exceeded at a particular location within a given time period. This pilot deals with regional long- and short-term PVHA. Regional assessments are crucial for a better land-use planning and for counter-measurements for risk mitigation actions of civil protection authorities. Because of the computational costs required to adequately simulate volcanic phenomena, PVHA is most based on single or very few selected reference scenarios. Independently of the degree of approximation of the used numerical model, PVHA for tephra loading and/or airborne ash concentration will necessitate a high number (typically several thousands, in order to capture variability in meteorological and volcanological conditions) of tephra dispersion simulations of which each is moderately intensive. This pilot will comprise both long- and short-term probabilistic hazard assessment for volcanic tephra fallout by adopting and improving a methodology recently proposed (Sandri et al., 2016) able to capture aleatory and epistemic uncertainties. Long term probabilistic hazard assessment for PDCs will also be envisaged, focussing on aleatory and epistemic uncertainties on Eruptive Source Parameters. Since tephra fallout models allow also a consistent treatment of spatially and temporally variable wind fields and can describe also phenomena like ash aggregation, an Exascale capacity will allow also to spatially extend, for the first time, the PVHA for evaluating potential impact from all active volcanoes in Italy on the entire national territory.