Hazard: an event or process that is potentially destructive.
Risk: the magnitude of a potential loss (of life, property or productive capacity) within the area affected by the hazard
The threat from a volcano can be regarded as constant unless it is extinct. Recently it emerged that a large number of volcanoes that had been considered dormant were actually active. There has been a call for the surveying of the world's volcanoes to reassess the risk. Over a million people live on the slopes of Mount Etna for example.
Options for controlling hazards are limited: most cannot be modified by humans.
Much can be done to minimise (ameliorate) the risk: careful land use zoning, warnings and community preparedness (although as was evident from Kobe earthquake this is not always enough...)
A report suggests that the Italian government is ready to approach the risk to people living on the slopes of Mount Vesuvius in a different way by offering them £18000 (€25000) each to move to safer areas, avoiding the need for evacuations when the volcano erupts. Officials in Naples hope that up to 1500 families will accept the cash. They want to empty 100 000 homes over the next 15 years. Scientists know that "sooner or later" the volcano will erupt. Its most 'famous' eruption was in 79AD, it last erupted in 1944. Around 600 000 people live in 19 towns inside the 'red zone': within a 4.3 mile radius of the mouth of the volcano. There is a long standing plan to evacuate a million people by train when vulcanologists give the warning. The prediction has to be accurate however, as the expense would be huge. Local officials are keen to reduce the amount of building work going on in the area. (The Guardian, 05/06/03)