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Three crustal sections, located in key zones of the Calabrian Arc and Southern Apennines, have been drawn on the basis of the available geological, geophysical, seismological and volcanological data. The purpose is to gather information on the state of stress at different crustal levels and to test to which extent data sampled at different time intervals may be consistently compared. The analysis allows for the individualization of the following sectors: 1.(1) Peri-Tyrrhenian belt, marked by a tensional state of stress down to the Moho depth;2.(2) Apenninic chain, subjected to tension only in its shallow portions and to a compressive regime at depth;3.(3) external chain-internal foretrough, characterized by a deep compressive regime which is expressed at the surface in its outermost zone only;4.(4) external foretrough-foreland, with tensional processes in the whole crust.Compressional processes are linked to the activity of a deep shear zone which causes the thrusting of the Tyrrhenian crust over the Adriatic crust and which seems to control the present distortion of the Calabrian Arc. The analysis suggests a change in the stress field and deformation mechanisms from the uppermost to the lowermost levels of the crust and an eastward migration with time of the compressional events. These facts would explain the contrasting evidence sometimes given by stress constraints derived from geological, seismological and volcanological data.

The most recent seismic profiles in southern Italy show the existence of a sudden thinning of the crust at the boundary between the chain and the Tyrrhenian margin. The abrupt change in thickness can be followed along a zone which has the same geometry in plan as the Calabrian arc. By considering these data and the gravimetric anomalies, it is possible to associate this crustal anomaly with a deep-seated shear zone which determines a crustal shortening of about 40–60 km which can only be a consequence of post-Tortonian tectonics. The surface equivalents of the deep-seated shear zone can be recognized, from north to south, in the alignment of the intra-Apenninic basins (Vallo di Diano, San Arcangelo, Potenza), in the Crati-Mesima graben and in the Mount Kumeta-Alcantara fault zone.

The investigated area is located on the southern slope of the NebrodiMadonie Mts. (northern Sicily, Italy). It was studied in order to obtain neotectonic evidence by means of fracture measurements, morphotectonic and hydrographical patterns, aerial photographs and satellite analysis. The results were compared with the well-known geological structures.