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. Shortwavelength
(∼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 grownwithin a recent and still active transpressional field. A major structural culmination bound by foreand
retro-verging transpressional shear zones is represented by the Pollino mountain range and its offshore
extension in the Amendolara ridge, and a furtherSW-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.
