Integration of on-land and offshore geomorphological and structural investigations coupled to extensive radiometric dating of co-seismically
uplifted Holocene beaches allows characterization of the geometry, kinematics and seismotectonics of the Scilla Fault, which borders the eastern
side of the Messina Strait in Calabria, Southern Italy. This region has been struck by destructive historical earthquakes, but knowledge of
geologically-based source parameters for active faults is relatively poor, particularly for those running mostly offshore, as the Scilla Fault does.
The ∼30 km-long normal fault may be divided into three segments of ∼10 km individual length, with the central and southern segments split in at
least two strands. The central and northern segments are submerged, and in this area marine geophysical data indicate a youthful morphology and
locally evidence for active faulting. The on-land strand of the western segment displaces marine terraces of the last interglacial (124 to 83 ka), but
seismic reflection profiles suggest a full Quaternary activity. Structural data collected on bedrock faults exposed along the on-land segment
provide evidence for normal slip and ∼NW-SE extension, which is consistent with focal mechanisms of large earthquakes and GPS velocity fields
in the region. Detailed mapping of raised Holocene marine deposits exposed at the coastline straddling of the northern and central segments
supplies evidence for two co-seismic displacements at ∼1.9 and ∼3.5 ka, and a possible previous event at ∼5 ka. Co-seismic displacements show a
consistent site value and pattern of along-strike variation, suggestive of characteristic-type behaviour for the fault. The ∼1.5–2.0 m average coseismic
slips during these events document Me ∼6.9–7.0 earthquakes with ∼1.6–1.7 ka recurrence time. Because hanging-wall subsidence cannot
be included into slip magnitude computation, these slips reflect footwall uplift, and represent minimum average estimates. The palaeoseismological
record based on the palaeo-shorelines suggests that the last rupture on the Scilla Fault during the February 6, 1783Mw=5.9–6.3 earthquake was at the
expected time but it may have not entirely released the loaded stress since the last great event at ∼1.9 ka. Comparison of the estimated co-seismic
extension rate based on the Holocene shoreline record with available GPS velocities indicates that the Scilla Fault accounts for at least ∼15–20% of
the contemporary geodetic extension across the Messina Strait.
