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This paper sheds light on the structural architecture and tectonic evolution of the Campania-Lucania segment of the Southern Apennines orogen through an integrated analysis of mostly unpublished and partly published (CROP-04 line) seismic reflection profiles, exploratory well logs and geologic-structural relations among the lithostratigraphic units of this region. The pre-orogenic Mesozoic-Neogene carbonate platform, margin-slope and basinal units that compose the upper orogenic level (Apennines fold and thrust belt) were detached from their basement during Miocene thrusting and form a heterogenous multilayer that was thrust above the Apulian foreland platform. The Apulian Platform itself was involved in Pliocene thick-skinned thrusting that controlled the style and localization of Quaternary transtension and extension. The velocity data from sonic logs, the well stratigraphy, and the seismic reflection facies were integrated through an accurate well-to-seismic tie, allowing the building of a specific velocity model for the time-to-depth conversion. We identified different seismic units with distinctive reflections attributes, which were assigned to the lithostratigraphic units logged in the wells. Our analysis documents the stratigraphic-structural arrangement of the thin-skinned thrusts sheets (Liguride Basin, Apennine Platform and Lagonegro-Molise Basin units) that form the Apennines fold and thrust belt. These units show strong lateral thickness changes because of both the original depositional environments and the non-coaxial deformation stages. In contrast, the underlying Apulian Platform is characterized by a regional anticlinorium (∼30–50 km wavelength) that, based on our new reconstruction, extends further west than hitherto known. The anticlinorium exhibits shorter-wavelength (<10 km) anticlines limited by N- to NE-verging thrust ramps, whose high dip (∼45°) suggests they root in the crystalline basement. Our work provides a sound link between surface and subsurface structural setting and an improvement of the geometry of the Apulian Platform, with important implications for structural and seismotectonic models of the region. • Seismic reflection profiles unravel the deep structure of the Southern Apennines. • Integrated use of seismic profiles, well data and geological maps. • Evolution from thin- to thick-skinned shortening. • Orogenic structure controlled by Meso-Cenozoic mechanical stratigraphy. [ABSTRACT FROM AUTHOR]

Seismological, geological and geodetic data have been integrated to characterize the seismogenic structure of the late 2013-early 2014 moderate energy (maximum local magnitude MLmax = 4.9) seismic sequence that struck the interior of the Matese Massif, part of the Southern Apennines active extensional belt. The sequence, heralded by a ML = 2.7 foreshock, was characterized by two main shocks with ML = 4.9 and ML = 4.2, respectively, which occurred at a depth of ~17-18 km. The sequence was confined in the 10-20 km depth range, significantly deeper than the 1997-1998 sequence which occurred fewkm away on the northeastern side of the massif above ~15 km depth. The depth distribution of the 2013-14 sequence is almost continuous, albeit a deeper (16-19 km) and a shallower (11-15 km) group of events can be distinguished, the former including the main shocks and the foreshock. The epicentral distribution formed a ~10 km long NNW-SSE trending alignment, which almost parallels the surface trace of late Pliocene-Quaternary southwest-dipping normal faults with a poor evidence of current geological and geodetic deformation. We built an upper crustal model profile for the eastern Matese massif through integration of geological data, oil exploration well logs and seismic tomographic images. Projection of hypocentres on the profile suggests that the seismogenic volume falls mostly within the crystalline crust and subordinately within the Mesozoic sedimentary cover of Apulia, the underthrust foreland of the Southern Apennines fold and thrust belt. Geological data and the regional macroseismic field of the sequence suggest that the southwest-dipping nodal plane of the main shocks represents the rupture surface that we refer to here as the Matese fault. The major lithological discontinuity between crystalline and sedimentary rocks of Apulia likely confined upward the rupture extent of the Matese fault. Repeated coseismic failure represented by the deeper group of events in the sequence, activated in a passive fashion the overlying ~11-15 km deep section of the upper crustal normal faults. We consider the southwest-dipping Matese fault representative of a poorly known type of seismogenic structures in the Southern Apennines, where extensional seismogenesis and geodetic strain accumulation occur more frequently on NE-dipping, shallower-rooted faults. This is the case of the Boiano Basin fault located on the northern side of the massif, to which the 1997-1998 sequence is related. The close proximity of the two types of seismogenic faults at the Matese Massif is related to the complex crustal architecture generated by the Pliocene-early Pleistocene contractional and transpressional tectonics. [ABSTRACT FROM AUTHOR]

SUMMARY We present an improved evaluation of the current strain and stress fields in the Southern Apennines (Italy) obtained through a careful analysis of geodetic, seismological and borehole data. In particular, our analysis provides an updated comparison between the accrued strain recorded by geodetic data, and the strain released by seismic activity in a region hit by destructive historical earthquakes. To this end, we have used nine years of GPS observations (2001-2010) from a dense network of permanent stations, a data set of 73 well-constrained stress indicators (borehole breakouts and focal mechanisms of moderate-to-large earthquakes) and published estimations of the geological strain accommodated by active faults in the region. Although geodetic data are generally consistent with seismic and geological information, previously unknown features of the current deformation in southern Italy emerge from this analysis. The newly obtained GPS velocity field supports the well-established notion of a dominant NE-SW-oriented extension concentrated in a ∼50-km-wide belt along the topographic relief of the Apennines, as outlined by the distribution of seismogenic normal faults. Geodetic deformation is, however, non-uniform along the belt, with two patches of higher strain-rate and shear-stress accumulation in the north (Matese Mountains) and in the south (Irpinia area). Low geodetic strain-rates are found in the Bradano basin and Apulia plateau to the east. Along the Ionian Sea margin of southern Italy, in southern Apulia and eastern Basilicata and Calabria, geodetic velocities indicate NW-SE extension that is consistent with active shallow-crustal gravitational motion documented by geological studies. In the west, along the Tyrrhenian margin of the Campania region, the tectonic geodetic field is disturbed by volcanic processes. Comparison between the magnitude of the geodetic and the seismic strain rates (computed using a long historical seismicity catalogue) allow detecting areas of high correlation, particularly along the axis of the mountain chain, indicating that most of the geodetic strain is released by earthquakes. This relation does not hold for the instrumental seismic catalogue, as a consequence of the limited time span covered by instrumental data. In other areas (e.g. Murge plateau in central Apulia), where seismicity is very low or absent, the yet appreciable geodetic deformation might be accommodated in aseismic mode. Overall, the excellent match between the stress and the strain-rate directions in much of the Apennines indicates that both earthquakes and ground deformation patterns are driven by the same crustal forces. [ABSTRACT FROM AUTHOR]

Abstract: An integrated analysis of geomorphologic and structural data, offshore seismic profiles and local network seismicity, is used to shed light on the hitherto poorly known active deformation field that affects the Southern Apennines orogen in northern Calabria region. In the Southern Apennines, Middle Pleistocene waning of Miocene–Early Pleistocene thin-skinned frontal thrust belt motion toward the Apulian foreland to the NE was coeval to onset of regional uplift, which is documented by flights of raised marine terraces. Short-wavelength (∼5–10 km) and amplitude (∼20–50 m) undulations are superposed to the regional uplift (∼100 km length and ∼500 m amplitude scale) profile of Middle–Upper Pleistocene marine terraces on the Ionian Sea coast of northern Calabria stretching along the borders of the Sila and Pollino mountain ranges and across the intervening Sibari coastal plain. The secondary undulations spatially coincide with the last generation of ∼W- to ∼WNW-striking folds traced in bedrock and locally within Early to Middle Pleistocene continental to transitional deposits. The very recent activity of these structures is highlighted by a range of fluvial geomorphic anomalies and by involvement in folding and locally transpressional faulting of the Middle Pleistocene and younger depositional sequences submerged beneath the continental shelf. We argue that the local-scale, but pervasive undulations in the deformation profile of marine terraces represent shallow-crustal folds grown within a recent and still active transpressional field. A major structural culmination bound by fore- and retro-verging transpressional shear zones is represented by the Pollino mountain range and its offshore extension in the Amendolara ridge, and a further SW-directed transpressional belt is found in northern Sila and adjacent sea bottom. Epicenter distribution and focal solutions of low- to moderate crustal earthquakes illuminate the two NW-SE trending structural belts beneath the Amendolara ridge and northern Sila, where partitioning between thrust and left strike-slip motion occurs in response to ∼E to ∼NE directed shortening. A local ∼NW-SE extension is recorded by fault-kinematic analysis on NE-SW striking fault segments parallel to the coast on the eastern flank of Pollino. These small-length normal faults do not form a through-going lineament, rather they accommodate the seaward collapse of the uppermost crust above the deeper shortening compartment. Conversely, the active transpression testified by geomorphic, structural and seismicity data is accommodated along deep-seated oblique back-thrusts that involve the Apulian foreland plate underlying the now inactive thin-skinned accretionary wedge down to near-Moho depths. In light of the tight interlacing between regional and local components of deformation affecting the marine terraces, we suggest that the large-scale uplift in this sector of Calabria may reflect whole crustal-scale folding. The novel seismotectonic frame reconstructed for this region is consistent with GPS velocities suggesting that large part of geodetic shortening detected between the Apennines and the Apulian block on the eastern side of southern Italy might be accommodated in northern Calabria. [Copyright &y& Elsevier]

The NW–SE trending Val d’Agri extensional basin is one of the regions in Italy with the highest seismogenic potential. Field data do not univocally define which of the fault systems bordering the basin on the two opposite sides is accommodating the active deformation. In this study, we detect and locate, by using an automatic picking procedure, almost 2000 low-magnitude earthquakes (−0.2 < ML < 2.7) recorded by a dense network during a 13-months-long seismic experiment. Events are mostly located along the southwestern flank of the basin. To the south, intense swarm-type microseismicity defines a major cluster ∼5 km wide from 1 to 5 km depth. To the west, a clear alignment of events, characterized by normal faulting kinematics, defines a NE-dipping normal fault between 1 and 6 km depth. The upward continuation of this structure, ∼5 km long, matches a mapped active normal fault recognized by field and palaeoseismological surveys. A temporal correlation found between the intense swarm-type microseismicity and the water level changes in the nearby artificial Pertusillo lake suggests that this seismicity is reservoir-induced. [ABSTRACT FROM AUTHOR]

Analysis of high-resolution seismic profiles integrated with archaeological data along the coast has allowed quantifying the last ∼10 ka BP displacements in the offshore part of the Campi Flegrei resurgent caldera, one of the world's highest-risk volcanic areas. Previous onland studies revealed that, following the Neapolitan Yellow Tuff (NYT) eruption at 15 ka, post-caldera evolution was associated with rapid ground uplift and subsidence cycles. In this paper, we use the stacking pattern of Prograding Wedges (PWs) and Aggrading Fills (AF) to reconstruct relative sea-level changes and estimate the amount of vertical deformation in the Pozzuoli Bay, the submerged part of the caldera. We document five generations of prograding wedges (PW1 to PW5), associated with as many periods of relative ground stability between uplift and subsidence. Instead, deposition of aggrading fills above prograding wedges underpins the subsidence that typically follows volcanic unrest and uplift. The older wedges PW1 and PW2 are larger and likely indicate whole-caldera uplift events. In particular, the development of PW2 starting from ∼5.2 ka is related to the rapid growth of a resurgent dome in the central part of the caldera. After ∼3.7 ka, subsidence prevailed in the caldera leading to deposition of an aggrading fill (AF2). However, subsidence was interrupted by short-term uplift episodes in historical times at (100 BCE-100 CE, 600–700 CE, 1430–1538 CE) that led to the growth of comparatively minor-sized wedges PW1 to PW3, respectively. Displacement of coastal infrastructures of the Roman age (∼2 ka BP) is consistent with the vertical motion retrieved by the seismostratigraphic analysis, and further indicates the existence of two deformation signals. A short-wavelength signal confined to the Pozzuoli Bay reflects the contribution of an intra-caldera source. This signal is superposed to a long-wavelength regional subsidence increasing between Naples and Procida Island from 1.5 to 2 mm/a, respectively. The east-to-west enhancing subsidence likely reflects the transition between the uplifting Apennines and the foundered Tyrrhenian back-arc basin. • High-resolution seismic profiles analysis in the offshore Campi Flegrei caldera • Seismostratigraphic bodies document relative sea-level changes • Quantitative reconstruction of vertical ground displacements in the Holocene • Roman-age coastal remains constrain ground deformation in the last 2 ka. • We disentangle the contribution of intra-caldera dynamics and regional tectonics. [ABSTRACT FROM AUTHOR]

Foreland contraction and hinterland extension in the Southern Apennines orogen of Italy produced a complex spatial and temporal pattern of vertical and horizontal displacement. Remarkably, Late Miocene to mid-Pleistocene foreland migration of the contractional front at∼16 mm yr−1 was not accompanied by uplift and the frontal thrust belt remained at or below sea level. Only following a mid-Pleistocene reduction in horizontal displacement did the frontal thrust belt and foreland begin uplift at∼0.5 mm yr−1, a rate that increased to∼1 mm yr−1 after 125 ka. Although the extensional hinterland experienced net subsidence during formation of the Tyrrhenian basin, an extensional transition zone adjacent to the frontal thrust belt records sustained uplift at∼0.3 mm yr−1. The interaction of preexisting crustal structure and deep tectonic processes resulted in time-integrated displacement rates suggesting steady-state deformation for periods of 106 years. Displacement rate changes were abrupt and occurred over intervals of 105 years or less.Terra Nova, 00, 1–6, 2005 [ABSTRACT FROM AUTHOR]

Abstract: The Lucania Apennines form the frontal part of the Apennines in Southern Italy. This orogenic belt was formed in response to late Miocene–Early Pleistocene shortening and allochthon emplacement toward the northeast, and was subsequently affected by extensional faulting which migrated to northeast ahead of the thrust system. As a result, contraction structures are found associated to Pliocene–Early Pleistocene thrust-top basins in the NE part of the area, whereas extensional faults shape Middle Pleistocene–Holocene basin on the SW sector. The main structural grain of the belt is NW–SE, but E–W structures are widespread in the area as a result of phases of non-coaxial thrusting and strike-slip faulting. The analysis, one by one, of the components of the Gravity Gradient Tensor (GGT) has proved to yield a fine image of the structural setting of the investigated area. GGT is a second rank tensor containing the second spatial derivatives of the gravity potential and in this paper is used instead than the more traditional gravity data. The Tzz component allows an accurate description of the location and of the shape of basins and other structures, but different components of the GGT provide even more detailed insights for such structures. In particular, we found that the Tzy and Tyy locate well those structures trending closer to the E–W direction for both thrust-top and extensional basins, and their termination against the main NW–SE structures. The combined use of components of GGT provides a finer definition of the anomaly sources particularly if a good knowledge of their strike and depth is independently estimated with other geological and geophysical investigations. [Copyright &y& Elsevier]