GIS and Volcanic Risk Management

Volcanic catastrophes constitute a major problem in many developing and developed countries. In recent years population growth and the expansion of settlements and basic supply lines (e.g., water, gas, etc.) have greatly increased the impact of volcanic disasters. Correct land-use planning is fundamental in minimising both loss of life and damage to property. In this contribution Geographical Information Systems (GIS), linked with remote sensing technology and telecommunications/warning systems, have emerged as one of the most promising tools to support the decision-making process. Some GIS are presented for two volcanic areas in Italy, Mt. Etna and Vesuvius. GIS role in risk management is then discussed, keeping in mind the different volcanic scenarios of effusive and explosive phenomena. Mt. Etna system covers a large area (more than 1,000 km2) potentially affected by effusive phenomena (lava flows) which cause damage to both houses and properties in general. No risk to life is expected. The time-scales of lava flows allow, at least in principle, modification of the lava path by the building of artificial barriers. Vesuvius shows typically an explosive behaviour. In the case of a medium size explosive eruption, 600,000 people would potentially have to be evacuated from an area of about 200 km2 around the Volcano, since they are exposed to ruinous, very fast phenomena like pyroclastic surges and flows, lahars, ash fallout, etc. Ash fallout and floods/lahars are also expected in distal areas, between Vesuvius and Avellino, downwind of the volcano. GIS include digital elevation models, satellite images, volcanic hazard maps and vector data on natural and artificial features (energy supply lines, strategic buildings, roads, railways, etc.). The nature and the level of detail in the two data bases are different, on the basis of the different expected volcanic phenomena. The GIS have been planned: (a) for volcanic risk mitigation (hazard, value, vulnerability and risk map assessing), (b) to provide suitable tools during an impending crisis, (c) to provide a basis for emergency plans.