Interplay of tectonic and dynamic processes shaping multilayer extensional system in southern-central Apennines.

High-hazard seismic zones can remain silent over centuries with meager seismicity rates challenging our understanding of seismic processes. We focus on the comprehensive analysis of cascading episodes of swarms and seismic sequences following the 2009 L'Aquila mainshock (MW 6.3) in the southern-central Apennine that previously experienced ~ M7 earthquakes. We enhance the seismic catalog, unmasking low-magnitude seismicity down to completeness magnitude ML ~ 0, and we unveil that the microseismicity might be secondarily triggered by the L'Aquila mainshock, influencing the frictional properties in the nearby fault zones or opening fault valves generating the intense seismic activity detected from 2009 to 2013. The diffusivity, observed in the most seismic episodes, and the high Vp/Vs values (> 1.88) indicate fluid circulation promoting multilayered extensional seismicity within 11-15 km and 16-23 km depth ranges. Mapping the 3D distribution of seismicity alongside geological data reveals an evident tectonic influence, unveiling unknown geometric aspects and providing the first evidence of a NNE-dipping deformation zone bounding at depths of 11-15 km the overlying fault system. Deeper seismicity suggests a mantellic CO2 ascending shape. These findings enrich the literature on tectonic seismic swarms in extensional domains, providing essential constraints on fluid involvement in the seismic processes and contributing to forthcoming discussions on the seismotectonic setting in high-seismic-risk areas of the Apennines of Italy.

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QUIN database integrates and organizes structural-geological information from published and unpublished sources to constrain deformation in seismotectonic studies.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.