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Sicily is characterised by active deformations, as suggested by the presence of very recent faulted deposits and by widespread seismicity. The northern portion of the Sicilian belt has undergone strike-slip tectonics since the Pliocene, as the effect of the south Tyrrhenian border dynamics. Integrated methodologies of analysis have been utilised to evaluate the neotectonic setting of the northern sector of the island. To this aim, we have elaborated mesostructural, morphotectonic and morphometric data obtained from field survey, photogeological analysis and from the elaboration of digital elevation model (DEM) data relative to 31 drainage basins. The data sets have been compared with the uplift rate and seismicity distributions, allowing us to recognise different crustal blocks into which the northern Sicily chain may be divided. Each block of the chain reflects the characteristic morphometric pattern of the drainage basins. The morphostructural setting, the distribution of seismicity and the orientation of the recent faults indicate that the main narrow neotectonic deformation zones bounding the crustal blocks range from NW-SE, NE-SW and W-E.

Extensional structures of different ages characterize the Sicilian fold-and-thrust belt. Normal faults ranging in geometry from stepped to listric and formed in different geodynamic settings significantly controlled the pattern of syn-tectonic deposits. Since Mesozoic times Sicily has experienced deformation related to the opening of the Tethys Ocean. Between the Upper Triassic and the Cretaceous normal, strike- and oblique-slip faults, developed in northern Sicily, in the framework of a transtensional deformation regime induced by the oblique rifting of the African and European continental passive margins. Since Tertiary times a reversal in the general relative plate motion induced convergence, followed by collision of the European and African margins. Neogene compressional deformations were locally associated to extensional structures related to the orogenic wedge taper and to the Pliocene-Pleistocene Tyrrhenian Basin evolution. The persistent activity of extensional structures at different times and within different tectonic pictures is magnificently preserved in the following Triassic-to-Recent stratigraphic record: (i) carbonates were deposited on the Jurassic passive margin, formed by neritic platforms and intervening pelagic basins; (ii) the Cretaceous extension in the Africa plate boundary followed Late Triassic-Early Jurassic transtension due to Neotethys stretching; (iii) clastic deposition occurred during Neogene chain building ahead of the advancing thrust front (foredeep deposition) and in the inner sectors of the orogenic wedge (perched deposition in extensional setting); (iv) the perched-basin deposition at the rear of the wedge was probably related to the extensional collapse of the taper during the Late Miocene and (v) the attenuation of previously thickened lithosphere corresponds to the onset of the Tyrrhenian stretching.

The Peloritani Mts. in Northeastern Sicily are part of the Sicilian orogenic belt interposed between the Tyrrhenian basin and the Ionian Basin. In the Tyrrhenian basin crustal thinning has been active since the late Miocene, whereas wedge accretion (External Calabrian Arc) has occurred in the Ionian basin, due to the north-westward subduction of the Ionian Plate below the Calabrian-Peloritani Arc. Strike-slip tectonics in NE Sicily occurred during Plio-Pleistocene times. Faulting caused a non-uniform uplift rate of the Plio-Pleistocene deposits, which are elevated up to 500 m above sea level. The structural pattern is mainly represented by NW-SE and N-S/NNE-SSW trending transcurrent faults which form asymmetric tectonic depressions. Normal and reverse oblique-slip faults are associated with large-scale strike-slip deformation bends, and form releasing and restraining structures. The normal faults are mostly listric and flatten at very shallow levels, in places re-activating older thrusts. Transtension in the northern coastal sectors is southwards, counteracted by transpression, which is represented by high-angle reverse faults in the Peloritani thrust front. High seismic activity is mostly located within these bands, both on land and in the Tyrrhenian offshore, indicating active deformation processes. Focal solutions suggest that the Peloritani Mts. are characterised by extension and transcurrent kinematics in agreement with the stress field resulting from the orientation of the outcropping strike-slip structures. A cards-pack non-uniform rotation around a vertical axis in the Peloritani thrust stack is proposed to explain the geometrical pattern of the strike-slip faults. Within the main W-E trending shear zone, the minor structures result from simultaneous extension, transcurrent movement and compression in each band, transferring the strain from the Tyrrhenian sectors (dominated by crustal thinning) to the Peloritani thrust front.

Syn-orogenic extension has been recognised in Northern Sicily. Mesoscopic analysis has been carried out in three key areas, where folded-and-thrust Mesozoic-to-Tertiary rocks crop-out. The three examples are inherent to Portions Of tectonic Units Which occupy progressively more internal positions in the Sicilian chain from west to east. The extensional deformation is mainly represented by low-angle normal faults and shear bands. A common kinematic process seems to affect the other sector of the chain during the extension and is represented by a generalized negative inversion of previous layer-parallel shear bands and detachments related to the thrusting. The extensional deformation occurred during the late Miocene. It significantly modifies the architecture of the chain through the sliding-back of the tectonic units and may be related to the evolution of the wedge taper.

The foredeep deposits of Northern Sicily, indicated as Sicilidi units, have undergone different deformations' since Oligocene time. The resulting tectonic Structures, analysed in several outcrops in the Eastern Madonie Mts, are 1 cm-to- 100 m in scale and are similar to the larger structures forming the Sicily belt, allowing for scale extrapolation. Also the overprinting relationships of the minor structures recorded in the so-called Tufiti di Tusa reflect the sequence of fault activation which determined the present-day geometry of the tectonic units, suggesting that the tectonic evolution of the foreland basin developed during the stacking of the Maghrebide fold-and-thrust belt. The overprinting relationships between the mesoscopic structures indicate that the flysch-like Succession (Tufiti di Tusa Fin. auct.) experienced layer-parallel extension and sediment compaction, followed by thrusting, low-angle normal faulting and renewed compression/transpression. The earlier episode of extension is related to the tectonic regime which affected the foredeep ahead of the thrust front during the Oligocene. Compression, in places represented by fault reactivation and inversion, reflects the foredeep deformation, progressively incorporated into the belt during the Miocene. The second event of extension overprints folding and faulting, in places inducing negative inversion of the contractional structures during the Late Miocene, and is related to chain collapse on reaching supercritical wedge taper conditions. The transpressional neotectonic structures reflect the shear zone which has affected the Southern Tyrrhenian margin since the Pliocene.

The northern coast of Sicily and its offshore area represent a hinge zone between a sector of the Tyrrhenian Basin, characterized by the strongest crustal thinning, and the sector of the Sicilian belt which has emerged. This hinge zone is part of a wider W-E trending right-lateral shear zone, which has been affecting the Maghrebian Chain units since the Pliocene. Seismological and structural data have been used to evaluate the seismotectonic behavior of the area investigated here. Seismological analysis was performed on a data set of about 2100 seismic events which occurred between January 1988 and October 2002 in the Southern Tyrrhenian Sea. This paper focuses in particular on a set of data relating to the period from 6th September 2002, including both the main shock and about 540 aftershocks of the Palermo seismic sequence. The distribution of the hypocenters revealed the presence of two main seismogenic zones. The events of the easternmost zone may be related to the Ionian lithospheric slab diving beneath the Calabrian Arc. The seismicity associated with the westernmost zone is closely clustered around a sub-horizontal regression plane contained within the thinned Southern Tyrrhenian crust, hence suggesting that this seismogenic zone is strictly connected to the deformation field active within the hinge zone. On the basis of both structural and seismological data, the brittle deformation pattern is characterized by high-angle faults, mainly represented by transcurrent synthetic right-lateral and antithetic left-lateral systems, producing both restraining/uplifting and releasing/subsiding zones which accommodate strains developing in response to the current stress field (characterized by a maximum axis trending NW-SE) which has been active in the area since the Pliocene. The cluster of the seismic sequence which started with the 6th September 2002's main shock is located within the hinge zone. The distribution of the hypocenters relative to this sequence emphasizes the presence of a high-angle NE-SW-oriented deformation belt within which several shear surfaces are considered to be found sub-parallel to that established for the main shock. The kinematics of all these structures is consistent with a compressive right-lateral focal mechanism.

Asymmetric anticlines with overturned or steeply dipping forelimbs and gently dipping backlimbs are generally interpreted as thrust-related folds. Fold asymmetry occurs as a consequence of forelimb rotation. If deformation takes place in environments dominated by submarine sedimentation, the limbs coincide with the slope (depositional surface) and rotation reflects slope steepening. If folds are nucleated in poorly or unlithified deposits, growth geometry also depends on the properties of the media, such as cohesion and the angle of internal friction. For cohesionless deposits, the tilting of the slope influences the equilibrium of the soft sediments, resulting in gravity-driven flow, re-mobilisation or in situ compaction. The occurrence of mass re-mobilisation is also connected with the limb tilting/lithification ratio. Hence, the presence of non-primary bedding geometries or soft-sediment deformations in folding-related growth strata may provide useful tools for deciphering contractional kinematics. Deformation of underlithified sediments during thrust-related folding is recorded in the outer sector of the Neogene Sicily chain (Central Mediterranean). Deformation occurred during the building of the Pliocene chain. Folding is the driving mechanism of the growth stratal pattern. Fold nucleation and amplification influenced the inclination of the slope of the basin floor where sediments were deposited. Slump and stretching structures in soft sediment occurred during folding and mass accumulation at the base of limbs led to a decrease in slope inclination. Analysis of fault-related fold and gravity-driven geometries enable us to reconstruct the contractional kinematics and the behaviour of syn-tectonic deposits that modify the growth fold pattern in terms of limb-hinge change of length-thickness.