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An integrated investigation including geological, geomorphological, geophysical and structural survey, tephra analyses, 14 C and 40 Ar/ 39 Ar dating, as well as paleoseismic trenching along the N-Matese fault system is presented. The study allowed the characterization of the tectonic mobility of this structure as well as the associated Bojano basin sedimentary-tectonic evolution since the early Middle Pleistocene, providing also new clues concerning the fault historical activity and the associated Mw > 6.5 earthquakes. We have found lines of evidence for > 1 mm/yr slip rate along the presently buried Bojano fault during the mid Middle Pleistocene, and similar rates for the main fault segments paralleling the Matese flanks. The buried Bojano fault significantly slowed down during the last 300 kyr, ceasing its activity before the Holocene. In turn, the segments outcropping along the Matese flanks reactivated at the onset of Late Pleistocene, after a long period of quiescence (480–110 ka), with robust slip rates that would seem even accelerating in post LGM times. Paleoseismic data suggest the occurrence of four Mw > 6.6 earthquakes in the past 3 ka, three of which match the little known 280 BC event, and the devastating 1456 and 1805 earthquakes. [ABSTRACT FROM AUTHOR]

Abstract: Morphological, stratigraphical and structural investigations integrated with palaeomagnetic and tephrostratigraphic studies and 40Ar/39Ar measurements allowed us to define the Quaternary tectonic–sedimentary evolution of the epicentral area of the L''Aquila 2009 earthquake (Mw 6.3). This area roughly matches the Paganica–San Demetrio–Castelnuovo (PSC) intermountain basin filled by a fluvio-lacustrine succession that is variously deformed by normal faults. At its early stage (Early Pleistocene; ca 2 Ma), the basin hosted a lake that was characterised by whitish carbonate silt and mud deposition. Towards the end of the Early Pleistocene, this was partly filled by a south-eastward prograding deltaic system. The south-easternmost portion of the deltaic system was successively abandoned and eroded, while sedimentation of a braided river system developed in a smaller area westwards. Before 780 ka, this fluvio-lacustrine system (the Lower PSC syntheme) ended, and the area underwent erosional and pedogenic processes. These processes continued up to >460 ka, with the onset of fluvial gravel and volcanic-rich silty sand deposition over a narrow area of the south-western PSC basin (an earlier unit of the Upper PSC syntheme, early Middle Pleistocene). Around 460 ka, when most of this area was again subjected to denudational processes, the sedimentation migrated into the previously exposed north-western area of the PSC basin, where fluvial/alluvial sediments were deposited, between ca 460 ka and ca 350 ka (a later unit of the Upper PSC syntheme). Between ca 350 ka and the present, the sedimentation continued uninterrupted in a slight westwards restricted area of the PSC basin (Upper–Late PSC syntheme). The significant contraction of the basin, the shifting of its depocentre, the variation in its geometry and in the spatial distributions and thicknesses of the units constituting the Lower, Upper and Late PSC synthemes, provide evidence for strong tectonic control. This resulted in progressive reduction of the activity of the south-easternmost tectonic structures and parallel migration of the fault activity on the westernmost structures. In this perspective, the fault system responsible for the L''Aquila 2009 earthquake can be seen as the most recent expression of a long-lasting westwards polarised process of tectonic activity transfer. [Copyright &y& Elsevier]

We investigated the late Upper Pleistocene activity of the eight main faults that comprise the active, dip-slip Gran Sasso fault system (GSFS) in the Gran Sasso d'Italia Massif (central Italian Apennines; 2912 m a.s.l.). We carried out novel paleoseismological analyses at four sites of three different fault segments, and reviewed the data of the previous results for three other segments. We carried out several topographic profiles across the offset hillslopes, alluvial fans, glacial cirques, moraines, and valley floor. Through the dozen radiocarbon datings that were combined and cross-checked with many other ages published in previous studies, we have provided robust slip-rates and reconstructed the Holocene seismic history of this fault system. Paleoseismic analyses revealed the presence of three consecutive earthquakes since the onset of the Late Holocene, which were separated by 3.3 ky and 2.2 ky, respectively. The last one occurred in the 13th–14th century CE, a time-span that fits with the catastrophic 1349 seismic sequence. Our review of the macroseismic intensity distribution of this sequence indicates the existence of two distinct mesoseismic areas; a southern one that was already related to the Aquae Iuliae fault rupture (Abruzzi-Campania-Molise borders), and a northern one that robustly matches the hanging-wall of the Gran Sasso fault system. Given the length of this fault system, we estimated Mw 7 for its entire rupture, which accounts for the total destruction of L'Aquila and the neighboring villages. This also accounts for the strong effects and severe damage suffered by several settlements in the para-Tyrrhenian far field, especially to buildings characterized by long fundamental resonance periods, as seen for the monuments of Rome. Although characterized by long recurrence times (2.8 ± 0.5 ky), our results suggest that as for all of the main silent faults of the eastern set of active structures in the central Apennines, this fault system has one of the largest seismogenic potentials of the whole Apennine chain, with seismic risk implications extended even to its far-field. • Paleoseismic trenching reveals the Holocene seismic history of the Gran Sasso fault. • Coseismic surface rupture length indicates a Mw 7.0 seismogenic potential. • The Gran Sasso fault rupture caused severe damage in Rome in the 1349 earthquake. [ABSTRACT FROM AUTHOR]

This work provides new insights on the use of a combined multidisciplinary approach forestimating trend and rates of valley incision in tectonically active mountainouslandscape. To this aim, here we present the results of a combined analysis includingstream terraces investigation, longitudinal profiles modelling and time-dependent,catchment-scale, geomorphometry obtained in the headwater sector of the Tronto River basin,located in the southern epicentral area of the 2016-2017 seismic sequence of CentralItaly.The most relevant tectonic structures in the area are the Mt. Gorzano fault (south-easternsector), the Sibillini Mts thrust (western sector) and the southern tip of the active Vettorefault, ie the seismogenic structure responsible for the 2016 mainshock. Geomorphometric analysis and stream long-profiles modelling were performed using a 5m-gridded DTM obtained starting from the altimetric dataset included in the 1:5,000topographic maps available for the whole study area in vector format. Time-dependentcatchment-scale R∕Sr metrics and long-profile indices (SL and χ) were computedrespectively using the hydrological tool in ESRI® ArcGIS and the TopoToolboxworking in Matlab®. Stream terraces dataset derives from field survey, integrated withthe visual inspection of a DTM-derived hillshade map and aerial/satellite imageryinterpretations. The combination of R∕Sr time-dependent metrics and stream terraces analysis allows toinfer the timing of the base level changes during upper Quaternary and the long-profilesmodelling provided interesting results for better comprehending the effects of these changeson the fluvial system. The analysis here performed provided new data useful for betterunderstanding the trend and rates of the valley deepening in the headwater sector of theTronto River, to reconstruct basin-scale modifications such as stream captures and, more ingeneral, resulted useful for better comprehending the morphoevolution of this tectonicallyactive key area of the Apennines. Nonetheless, our study did not allow to unravel therole exerted by the single active tectonic structures in the present and past fluvialmorphodynamics, because of the superimposed effects of large gravitational rock slopefailures on the spatial pattern of long-profiles anomalies and local base level variations. [ABSTRACT FROM AUTHOR]