Ischia Island: a model for sustainable development and natural risk mitigation

The island of Ischia has a land area of 46.3 square kilometers and a population of 64.115 inhabitants by 2019. The territorial density is 1,385 inhabitants per square kilometer. The environmental sustainability of Ischia is about 22 thousand inhabitants. In the year 2017 there were about 2.3 million tourists. The remarkable expansion of historical settlements on the Island in recent decades, without adequate planning that would pay attention to the geological hazard, has produced an exponential increase in risk, as it was shown by the disastrous earthquake that occurred in Casamicciola on 21 August 2017. The underestimation of volcanic, seismic and hydrogeological risks on the Island is incomprehensible due to the catastrophes that occurred with the historic eruption of 1302, the strong earthquakes of 1881 and 1883 and the disastrous flood of 1910. The historical data and the most recent ones produced through the monitoring of the Island allow to obtain the maps of the hazard of the territory. These maps are the basic tools for defining acceptable risk and structural interventions to reach this level. The entire Island is exposed to volcanic risk because its structure is an active volcanic field affected by the collapse of the Green Tuff Caldera, an area considered active. In the last 10 Ka eruptive activity developed mainly between the eastern edge of Mt. Epomeo and the eastern coast of the Island. The area with the greatest seismic risk develops on the northern edge of the Mt. Epomeo massif. The hydrogeological instability invests Mt. Epomeo and the floods develop both on the southern and northern side of the Island. The territory is divided into six Municipalities: Ischia, Casamicciola Terme, and Lacco Ameno to the north, Barano d’Ischia, Serrara Fontana and Forio to the south, but none of the six municipalities has an urban Plan and an inter-municipal Plan is missing. The government of the Island territory, characterized by valuable environmental elements and high risks, has to provide for a unitary action such as to allow the conservation of environmental parameters through the evaluation of environmental sustainability to the anthropic impact and the mitigation of risks. The model for such an intervention foresees: –– Map of volcanic, seismic and hydrogeological risks; –– Definition of Homogeneous Territorial Zone on the basis of the maximum expected damage - any measures to reduce the density of housing and construction; –– Destination of land use - Apply the Landscape Plan; –– Evaluation of the vulnerability of buildings and seismic adaptation of existing buildings; –– Realize an efficient infrastructural system of road and path networks to enhance escape routes; –– Develop equipment and public thermal resources activities. In this context of natural risks and extraordinary environmental resources it would be appropriate to set up an Advanced Research Center to be placed in an area destined for a Scientific-Naturalistic and Archaeological Park.