Tettonica attiva e recente, e manifestazioni gravitative profonde, lungo il bordo orientale del graben del Fiume Crati (Calabria settentrionale).

Recent and Active Tectonics, and Related Deep-Seated Gravitational Deformation, on the Eastern Border of the Crati Graben (Calabria, Southern Italy). The eastern border of the Crati graben (TURCO et alii, 1990; LANZAFAME & TORTORICI, 1981) is characterised by Quaternary extensional N-S striking faults, in its southern part, and WNW-ESE striking faults, in its northern part. The N-S striking faults are arranged into a westward down-stepping system, allowing the uplift of the Sila Massif (a crystallinemetamorphic horst) with respect to the Plio-Holocene deposits, which occur within the Crati graben. The master faults are represented by the «Rogliano-Cèlico-Serra Castellara» and the «Dònnici- San Pietro in Guarano-Luzzi» lineaments. From a morphological point of view, the N-S faults become more «fresh» from east to west. They show, at the mesoscale, a strike-slip component, gradually evolving from strongly left-lateral to moderately right-lateral. The WNW-ESE trending faults appear to be less fresh than the N-S ones. They led to the uplift of the San Lorenzo del Vallo metamorphic horst with respect to the Plio-Holocene deposits, and show at the mesoscale left-lateral evolving to dip-slip movements. In the study area, numerous deep-seated gravitational deformations (DRAMIS et alii, 1985; CRUDEN & VARNES, 1996) have been recognised, mainly in the transition zone between the above cited fault-systems, located in the F. Mucone drainage basin. There, the morphological evidence of the tectonic features is subdued, and the overall homogeneity of the meso-structural data is reduced. On the whole, seventy-six deep-seated gravitational phenomena have been mapped, characterised by at least one dimension greater than 500 meters: these affect about 15.5% of the study area considered - a figure far greater than was expected on the basis of available literature (SORRISO-VALVO, 1984; SORRISO-VALVO & TANSI, 1996). Deep-seated gravitational phenomena have been classified into the following main types: large-scale landslides (n. 37 cases), lateral spreads (2), and gravity-accommodated structural wedges (37). Finally, according to historical, instrumental, and paleoseismologic evidence (e.g. soil displacements and fault-scarp refreshments), the southernmost portion of the study area has been found to be the most active. Moreover, the earthquake of October 4th 1870 can be attributed to the «Rogliano-Cèlico-Serra Castellara» fault; the earthquakes of October 12th 1835 and of February 12th 1854 can both be attributed to the «Dònnici-San Pietro in Guarano-Luzzi» lineament.