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This multidisciplinary study conducted in the\ud area covered by sheet 348 ‘‘Antrodoco’’ of the Geological\ud Map of Italy contributes to the knowledge on an undissected\ud intermontane basin located at the transition between\ud the Gran Sasso and the Laga structural–paleogeographic\ud domains in the highly seismic Apennine axial zone. Geomorphological\ud analysis is used to infer the role of extensional\ud faults and to provide a relative chronology of the\ud capture phenomena that have led to a substantial reduction\ud of the catchment area since the Early Pleistocene. Geophysical\ud and stratigraphic data have been integrated into a\ud 3D model, enabling evaluation of the thickness and\ud geometry of the Quaternary sedimentary infilling. A\ud stratigraphic study, chronologically constrained according\ud to paleomagnetic results and 14C datings, highlights the\ud occurrence of a major unconformity related to changes in\ud the drainage network and suggests that during the Early\ud Pleistocene, the Montereale Basin experienced an initial\ud aggradation phase conditioned by the activity of local\ud tectonic structures and then evolved under the influence of\ud prevailing external factors. Finally, this study represents a\ud complete and integrated approach. This approach makes\ud possible, for the first time, the imposition of a number of\ud firm constraints on the geometry and evolution of this\ud under-explored intermontane basin, located in a key position\ud along the Apennines

We present a 1:20,000 scale map of the traces of the active Capitignano and San Giovanni faults in the area of the Montereale basin (central Apennines, Italy) covering an area of about 80 km 2 . Detailed fault mapping is based on high-resolution topography from airborne LiDAR imagery validated by extensive ground truthing and geophysical prospecting. Our analysis allowed the recognition of several features related to fault activity, even in scarcely accessible areas characterized by dense vegetation cover and rugged terrain. The identified fault traces run at the base of the NW-SE striking Montereale basin-bounding mountain front and along the base of the southwestern slope of the Monte Mozzano ridge, and have a length of about 12 and 8 km, respectively. Improving the knowledge of fault geometry is a critical issue not only for the recognition of seismogenic sources but also for surface fault hazard assessment and for local urban planning. The knowledge of the exact location of the fault traces is also crucial for the seismogenic characterization of the active faults by means of paleoseismological trenching.ARTICLE HISTORY

We conducted paleoseismic studies along the Montereale fault system (MFS; central Italy). The MFS shows geomorphological evidence of Late Quaternary activity and falls within the highest seismic hazard zone of central Apennines, between the epicentral areas of two recent earthquake sequences: 2009 L'Aquila and 2016–2017 central Italy. We excavated two trenches along the San Giovanni fault splay of the system, one intercepting the N140° striking bedrock main fault plane and the other cutting two subparallel fault scarps on the colluvial/alluvial deposits on the fault hanging wall. Excavations revealed repeated fault reactivation with surface faulting in prehistorical and historical times. We recognized and dated seven events in the last 26 kyr. The most recent ground‐rupturing event (evb1) possibly occurred 650–1,820 AD, consistent with one of the three main shocks that struck the area in 1,703 AD. A previous event (evb2) occurred between 5,330 bc and 730 bc, while older events occurred at 6,590–5,440 bc (evb3), 9,770–6,630 bc (evb4), and 16,860–13,480 bc (evb5). We documented two older displacement events (evb7 and evb6) between 23,780 bc and 16,850 bc. The minimum vertical slip rate at the trench site in the last 28–24 kyr is 0.3–0.4 mm/year. The inferred average recurrence interval for surface‐faulting events along the MFS is no longer than ~4 kyr. Based on the surface fault length ranging between 12 and 20 km, earthquakes with ≥M 6.0 are possible for the MFS. The MFS is an independent earthquake source, and its paleoseismic data are fully comparable with those known for faults in central Apennines.

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