Active faulting in the Calabrian arc and eastern Sicily

The Calabrian: are and eastern Sicily are areas of the central Mediterranea n where the effects of Quaternary tectonics are well preserved. The most im pressive tectonic feature in this region is represented::by a:major normal fault belt that runs more or less continuously along the inner side of the Calabrian are, extending through the Strait of Messina along the Ionian coa st of Sicily as far as the Hyblean Plateau. The distinct normal fault segme nts within:the belt, which during Pleistocene times have controlled the evo lution of major marine sedimentary basins, have lengths ranging from 10 to 45 km. They exhibit huge fault scarps which defines the fronts of the main: mountain ranges of the region (Catena Costiera, Aspromonte, Serre, Pelorita ni and Hyblean). Morphological features of fault scarps, and the age of the faulted rocks, suggest slip rates of 0.5-1.2 mm/year for the last 700 kyea r (Middle Pleistocene-Holocene), reaching values of about 2.0 mm/year in-th e areas of active volcanism. From a seismological point a view, the Calabri an are and eastern Sicily represent a very active area which is characteriz ed by crustal earthquakes, the largest of which reached in the last nine ce nturies an intensity of X-XI (6) < M less than or equal to 7.4). The occurr ence of intermediate and deep focus earthquakes located along the inner sid e of the;arc, beneath the southern Tyrrhenian Sea,is associated to the exis tence of a slab of Ionian lithosphere. The distribution of crustal seismici ty shows that most of the events which have occurred in the area, are locat ed in the hangingwalls of the main Quaternary normal faults hence suggestin g a strong relationship between seismic activity and the growth of extensio nal structures. Geological observations, together with seismological data, indicate-that normal faulting in the area results from the development of a main rift zone, related to an overall ESE-WNW extension, which also contro ls the evolutionary history of the magmatism in this sector, of southern It aly. (C) 1999 Elsevier Science Ltd. All rights reserved.