QUIN 2.0 - new release of the QUaternary fault strain INdicators database from the Southern Apennines of Italy.

QUIN database integrates and organizes structural-geological information from published and unpublished sources to constrain deformation in seismotectonic studies. The initial release, QUIN1.0, comprised 3,339 Fault Striation Pairs, mapped on 445 sites exposed along the Quaternary faults of central Italy. The present Data Descriptor introduces the QUIN 2.0 release, which includes 4,297 Fault Striation Pairs on 738 Structural Sites from southern Italy. The newly investigated faults span ~500 km along the Apennines chain, with strikes transitioning from ~SE to ~SW and comprehensively details Fault Striation Pairs' location, attitude, kinematics, and deformation axes. Additionally, it offers a shapefile of the fault traces hosting the data. The QUIN 2.0 release offers a significant geographic extension to the QUIN 1.0, with comprehensive description of local geometric-kinematic complexities of the regional pattern. The QUIN data may be especially relevant for constraining intra-Apennine potential seismogenic deformation patterns, where earthquake data only offer scattered or incomplete information. QUIN's data will support studies aimed at enhancing geological understanding, hazard assessment and comprehension of fault rupture propagation and barriers.

Complex trans-ridge normal faults controlling large earthquakes.

Studying faults capable of releasing moderate-to-strong earthquakes is fundamental for seismic hazard studies, especially in a territory that was subject to the strongest peninsular Italy earthquake (1857, Mw 7.1) and hosting the largest European oil field on-land. Fieldwork-based observations in the Campania-Lucania area highlight a SSW-dipping ~ 65 km-long normal-oblique-segmented fault, showing evidence of recent activity and possibly responsible for the 1857 earthquake. It crosses the Maddalena ridge, linking separate Quaternary basins. Two seismic reflection profiles cross the fault trace where it is buried beneath the Val d'Agri Quaternary deposits. Similarities between fault-controlled small basins in the highest portion of the massifs in the study area and the neighboring 1980 Irpinia area (1980 earthquake, Mw 6.9) are interpreted as evidence of trans-ridge fault activity. Kinematic analyses and the stress field inversion provide a N032-trending near-horizontal s3-axis, the same computed in literature for the Irpinia area, highlighting a deviation from the ~N045-axis which characterizes most of the Apennines. This study demonstrates how detailed fieldwork, supported by geophysics and innovative data analysis techniques, can unravel unknown faults while giving a novel interpretation of the trans-ridge faults' style in controlling strong earthquakes, moving away from classical interpretations, and providing a helpful approach in similar contexts worldwide.

Surface ruptures and off-fault deformation of the October 2016 central Italy earthquakes from DInSAR data.

Large magnitude earthquakes produce complex surface deformations, which are typically mapped by field geologists within the months following the mainshock. We present detailed maps of the surface deformation pattern produced by the M. Vettore Fault System during the October 2016 earthquakes in central Italy, derived from ALOS-2 SAR data, via DInSAR technique. On these maps, we trace a set of cross-sections to analyse the coseismic vertical displacement, essential to identify both surface fault ruptures and off-fault deformations. At a local scale, we identify a large number of surface ruptures, in agreement with those observed in the field. At a larger scale, the inferred coseismic deformation shows a typical long-wavelength convex curvature of the subsiding block, not directly recognizable in the field. The detection of deformation patterns from DInSAR technique can furnish important constraints on the activated fault segments, their spatial distribution and interaction soon after the seismic events. Thanks to the large availability of satellite SAR acquisitions, the proposed methodological approach can be potentially applied to worldwide earthquakes (according to the environmental characteristics of the sensed scene) to provide a wider and faster picture of surface ruptures. Thus, the derived information can be crucial for emergency management by civil protection and helpful to drive and support the geological field surveys during an ongoing seismic crisis.