Fallout of ballistic blocks and bombs ejected from eruptive vents representsa well-known hazard in areasproximal to volcanoes (mostly 5cm) has posed a real threat both to the manyvisitors reaching the summit area and to local infrastructure, and,therefore, has been selected as a case study. To quantify this hazard, a newparticle sedimentation model was calibrated with field data and then used forprobabilistic hazard assessments. For a fully probabilistic scenario thehazard zone covered 72km2 and included some 125km of paths androads, as well as 15 buildings. Evacuation on foot to a safe area wasestimated at almost 4h, but this could be reduced to less than 3h if twoshelters were provided. Our results show the importance of integratingprobabilistic hazard analysis of large-clast fallout within effectivestrategies of risk management and reduction, especially in the case ofvolcanoes where visitors can reach the summit areas.
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