Italy - Naples - Warning sign on Vesuvius

Warning sign of risk on the western slope of Vesuvius with the urban sprawl of Naples in the distance. The national emergency plan to protect the inhabitants from a possible eruption of the Vesuvius area has as its baseline the explosive event of 1631. Drafted by the scientific community has identified three areas with different hazard defined: the red zone, yellow zone and the blue zone. The red zone is the area immediately surrounding the volcano, and is in greater danger as potentially subjec (Photo by In Pictures Ltd./Corbis via Getty Images)