Reduction of environmental risk from capable faults : The case of the Eastern Etna region (eastern Sicily, Italy)

Abstract On the eastern flank of Etna volcano, movements along the NNW–SSE trending normal faults of the Timpe system generate recurrent, low magnitude very shallow seismic events that induce noteworthy ground surface effects. The Timpe system is the on-land extension of the Hyblean–Malta fault system, which is the likely source of the 1693 Maw 7.4 earthquake. Frequent creep phenomena occur both associated with seismic events and/or volcanic eruptions, and independent from them. These surface deformations are mainly confined in the eastern sector of the volcano apparatus and result from the interaction between regional tectonics and local volcano-tectonic processes. The widespread diffusion of cultural sites in this region even before the Greek civilisation testifies to the complex relationship of humans with a restless violent nature. Many Greek authors and myths refer to the frightening eruptions and earthquakes of Etna, but, at the same time, Strabo underlines the extreme fertility of the land due to the volcanic ash, and the quality of the local wine. So notwithstanding the evident risk, this region is one of the most densely inhabited regions of Sicily. Coseismic surface ruptures and creep are responsible for damaging effects on buildings, roads, railways and lifelines, including the water supply network. To reduce the environmental risk from faulting, APAT—Italian Agency for Environment Protection and for Technical Services—has compiled a georeferenced database, where capable faults, extract from ITHACA (Italy Hazard from Capable Faults) catalogue, and water supply and other environmentally sensible networks are overlapped to pinpoint zones of expected damage. This tool is fundamental in land planning and during an emergency, as seen during the 2002 Santa Venerina earthquake when the environmental agency needed to quickly verify the integrity of the water distribution and sewage networks.