Evidence for surface faulting earthquakes on the Montereale fault system (Abruzzi Apennines, central Italy)

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.Published2758-27766T. Studi di pericolosità sismica e da maremotoJCR Journa

Note Illustrative della Carta geologica d'Italia alla scala 1:50.000, F. 348 Antrodoco, Servizio Geologico d'Italia - ISPRA

Note illustrative redatte per il Foglio geologico n. 348 Antrodoco della Carta Geologica d'Italia alla scala 1:50.000. 396 pp

Sedimentology, palynology and new geochronological constraints on Quaternary deposits of the Corvaro intermontane basin (central Italy)

Two main depositional phases are recognized in the Middle-Late Pleistocene sedimentary sequences of the Corvaro tectonic depression (Latium, central Italy). To improve the chronological, palaeoenvironmental and palaeoclimatic frame of the area two boreholes were drilled. They allowed to estimate the thickness of deposits, to define the stratigraphy and to establish the presence, during the second phase, of a palustrine/lacustrine environment limited to the marginal sector of the Amara valley alluvial fan. The Corvaro 2 core was palynologically investigated. Pollen of nonarboreal plants dominates the assemblages, suggesting that a steppe characterized the environment during a glacial phase. Pollen of arboreal plants is scarce, and represented mainly by gymnosperm trees and shrubs. A slight expansion of deciduous oaks together with sparse occurrences of some other mesophilous trees is radiocarbon dated at around 30,000 years BP. These arboreal oscillations of the last glacial period are found for the first time in a mountain area of the Apennine region. Our results suggest that intermontane valleys, such as Valle del Salto, have probably played an important role in preserving biodiversity

Quaternary in Italy: Knowledge and perspectives

The selection of papers here presented aims to give an overview of topics and state-of-the-art research on the Quaternary in Italy, focusing the attention on the unsolved problems, and suggesting topics for future research. The actual importance of climate changes in shaping landscape and biota evolutionary dynamics during the Quaternary is among the key themes

Pollen and macrofossil analyses of Pliocene lacustrine sediments (Salto river valley, Central Italy)

The study of two sedimentary records sampled in the fluvio-lacustrine succession of high Salto river valley (Rieti, central Italy) was originated in the frame of the Geomorphologic Map of Italy (APAT, 2008) field survey and improved with a multidisciplinary approach addressed to a better knowledge of the Plio-Pleistocene continental environments of central Apennines. The two successions are associated to different sedimentary facies, with lateral heteropic relations: the deposits cropping out at Marano de' Marsi are thought to represent deposition in the distal portion of a lacustrine delta, while those of Borgorose took place in a frankly lacustrine environment. The sediment succession from Marano de' Marsi (11 m) was sampled from an outcrop, the one from Borgorose (24.5 m) from a drillhole. Palaeomagnetic investigations carried out on both sediment records indicate a normal magnetic polarity and very low magnetic susceptibility values. In the record from Marano de' Marsi section, gymnosperm pollen is prevailing. Four main and short angiosperm arboreal pollen oscillations can however be observed, the oldest of which more marked. The gymnosperms are mainly represented by Pinus haploxylon type, Pinta sylvestris type, Cedrus, Picea, Abies, Cathaya, Tsuga, Taxodium type. Among angiosperms the dominant taxa, some of which at present extinct in Italy, are Quercus, Zelkova, Ulmus, Carya and Pterocarya. The presence of pollen of subtropical taxa as Nyssa, cfr. Rhoiptelea, Liquidambar, Engelhardia is worth to be mentioned. The investigation was integrated also by a preliminary study of macrofossils. Fossil impressions with some organic matter of angiosperm and gymnosperm leaves and seeds/fruits were ascribed to Acer cfr. monspessulanum, Carpinus cfr. orientalis, Engelhardia, Fagus, Hedera, Liquidambar, Quercus, Rosa, Abies and Pinus. The 24.5 m long sediment core from Borgorose resulted very poor in pollen, with the same list of arboreal taxa, at present extinct in Italy, found at Marano de' Marsi, and a diagram was drawn only for the stretch of the core between 3 and 8.2 m. Gymnosperms (P. haploxylon type is dominant, and accompanied by P. sylvestris type, Picea, Taxodium type, Cedrus, and Tsuga) are always prevailing. The results obtained by this interdisciplinary investigation indicate that Marano de' Marsi and Borgorose successions can be possibly attributed to the Upper Pliocene (normal polarity Olduvai subchron) even if an older age, considering the present state of the art on Pliocene continental records, and the peculiarity of the site and of the region, cannot be excluded. (C) 2009 Elsevier Ltd and INQUA. All rights reserved

Carta Geologica dell'area pedemontana orientale della Majella (bacini dei Fiumi Aventino e Foro) scala 1:25.000

This map was realized as part of the ISPRA - Abruzzo Region agreement aimed at the prevention and mitigation of seismic hazard. The map depicts an area of the outermost sector of the central Apennines to the east of the Majella carbonate massif, in the catchment areas of the Aventino and Foro rivers, where prevalent terrigenous deposits and the allochthonous Molise succession, as well as Quaternary marine and continental deposits crop out. In this sector several tectono-stratigraphic units have been recognized, consisting of the platform succession of the Porrara Unit (Outer Abruzzi units) (), the platform carbonate-to basinal successions of the Majella and Casoli-Bomba Units (Apulia-Adriatic deformed units) (), and the allochthonous Molise units. They have complex structural relationships, that originated sequentially over a time interval from late Messinian to early Pleistocene. The tectono-stratigraphic units are separated by tectonic or gravitative contacts and largely obliterated by younger thrust-top deposits, and sediments of the Adriatic regressive cycle (Mutignano Formation, late Pliocene-early Pleistocene), as well as widespread continental deposits. After the emergence, between the middle Pleistocene and the Holocene, the area was mainly affected by erosion and by the sedimentation of prevailingly detrital and alluvial deposits, whereas the current morphogenesis is dominated by landslide phenomena. The most relevant aspects faced during the survey are connected to: i) the extreme space-time facies variability of the outcropping successions, ii) the complex interpretation of the tectonic/gravitative nature of the discontinuity between the allochthonous Molise units and the other units, iii) the reconstruction of the kinematic mechanisms of the main tectonic elements, and iv) the timing of the thrusting phases, constrained by the sedimentation of the unconformable successions of the thrust-top basins and the deposition of the regressive cycle. The marine formations were mapped according to the lithostratigraphic criteria of the CARG (Geological Cartography) Italian project carrying out original surveys at a 1:10,000 scale and biostratigraphic studies of foraminifera and nannofossils. The Quaternary continental deposits consist of fan, alluvial plain, and slope facies, and are subdivided into preliminary unconformity-bounded stratigraphic units, based on correlations with geomorphological criteria, characterization of relict and buried soils, and radiometric dating, paying particular attention to the nature of the basal and top bounding surfaces

Traces of the active Capitignano and San Giovanni faults (Abruzzi Apennines, Italy)

<p>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 km². 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.</p

Traces of the active Capitignano and San Giovanni faults (Abruzzi Apennines, Italy)

<p>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 km². 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.</p