G. Gabbianelli (Dipartimento di Scienze della Terra e Geoambientali, Universita' di Bologna, Bologna Italy)

G. Lanzafame & M. Neri (Istituto Internazionale di Vulcanologia, C.N.R., Catania, Italy)

The Chiancone volcanoclastic fan occupies, on the land and at sea, the base of the eastern flank of Mt. Etna. Its genesis can be traced to a collapse that, between the end of the Pleistocene and the Holocene, formed the ample depression of the Valle del Bove. Our marine geological data indicate that the Chiancone rests on an erosion surface 18,000 years old, which is formed by at least three overlapping bodies, with different sedimentary organisation, and which have a maximum thickness of 250 m. Surface data indicate a maximum thickness of between 400 and 800 m (according to the Authors), and the C14 age of the higher levels is about 5,000 years. The integration of surface and marine geological data allow the following to be stated:

1. the temporal interval within which the Chiancone was formed is between 18,000-5,000 years;
2. the total volume of the deposit, on the land and at sea, is congruent with that missing from the depression of the Valle del Bove;
3. its formation took place at different times and with different mechanisms of sedimentation.

The eastern flank of Mt. Etna is a highly inhabited zone. In this zone, up to proto-historic times and in climatic conditions similar to those of the present day, catastrophic volcanic-sedimentary events have taken place which include, among others, also gravity. This fact must be taken into consideration for a correct planning of the territory.