Explosive volcanoes in the Mediterranean area: hazards from future eruptions at Vesuvius (Italy) and Santorini (Greece)

Abstract

Santorini is the site of the famous Minoan eruption of the late Bronze Age and Vesuvius is the type locality for Plinian eruptions. Hazards from the eruption most likely to occur in the near future at these volcanoes are discussed. Downwind zones of Santorini can be affected by minor ash fallout and gas emission from a Vulcanian eruption of Nea Kameni, the most active post-caldera vent. More dangerous would be a sub-Plinian eruption from Columbus, a submarine volcano located 8 km NE of Santorini, whose eruption in 1649-1650 A.D. caused several casualties in Santorini, mostly by wind transported poisoning gas. Vesuvius last erupted in 1944 and its eruptive history includes periods of long quiescence, lasting centuries or tens of centuries, interrupted by violent Plinian or sub-Plinian eruptions. A sub-Plinian eruption is the reference event in the Civil Protection emergency plan. The scenario includes a Red Zone exposed to the risk of being invaded by pyroclastic flows and that should be entirely evacuated before the eruption onset, together with some nearby areas where there is a high risk of roofs collapse by overloading of fallout tephra (nearly 700,000 persons in total). The Red Zone is encircled by the Yellow Zone exposed to pyroclastic fallout and related risk maps are here commented. Another serious risk is associated with earthquakes of the pre-eruptive unrest phase. Because of the high seismic vulnerability of the buildings within the Red Zone, many of them might collapse before the evacuation order of the Red Zone be issued. Finally, the scientific difficulty of forecasting the time evolution of the eruption precursory phenomena is discussed together with the related civil protection implications.