Assessment of risk associated with tephra-related hazards

The ensemble of pyroclastic material injected into the atmosphere during explosive volcanic eruptions (i.e., tephra) has the potential to generate complex patterns of disruption at multiple temporal and spatial scales. Reducing associated risk requires a full characterization of the hazards associated with its dispersal, sedimentation, and aeolian remobilization and of various dimensions of vulnerability (e.g., physical, socio-economic, and systemic). Dedicated analytical and numerical models together with sophisticated probabilistic strategies have been developed for the description of the physical processes; however, due to the combination of a low frequency of volcanic eruptions and the infancy of associated risk studies, the characterization of vulnerability is still fragmentary and mostly focused on the physical acute damage. In this context, impact analyses have already provided fundamental insights into the vulnerability of various elements and systems and are essential to identifying important drivers of losses. Strategies of disaster risk reduction in volcanic regions will be effective only after the potential dynamic interaction between the geophysical event and exposed elements are understood and described