Elementi sismotettonici dell'Appennino meridionale.

Available geological and seismological data concerning the Southern Apennines and Northern Calabria are reviewed in this paper. Pronounced elliptical isoseismals are a common feature of the largest earthquakes occurring in the Southern Apennines, with major axes elongated in the moun- tain chain direction. Aftershock activity of the November 23, 1980 earthquake (Ms = 6.9) confirms this pattern, with a seismogenetic zone extended in the crust at depth higher than 10 km. Fault plane solutions indicate predominant normal faulting, with a few solutions showing strike slip motion. In particular this last type o( motion seems to occur along the main discon- tinuities ol the chain. This stress pattern is co- herent with the structural analysis deduced from the brittle deformations in pleistocenic sediments. Neotectonic activity in the last million years shows different vertical block movements of the Tyrrhenian side. with a predominance of subsi- dence, with respect to the Apenninic and Adriatic blocks. The amount of uplift in the mountain range, as shown by the movements since Pleisto- cene, is of the order of 1 mm/year, with associated normal faulting striking in the same direction of the mountain chain. The structural behaviour of this region is characterized by strong lateral inho- rnog(;neities, with sharp variations of the crustal and lithospheric properties in a direction ortogonal : to the Apenninic chain. Moreover this mountain belt is characterized by a lateral segmentation which are in most cases related to the boundaries of the rupture zones associated to the largest earth- quakes.