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Abstract: Landscape evolution in active mountain chains can be dominated by gravitational slope movements. This is observed in a large portion of the Reno river catchment, Apennines, Italy, where weak rocks, such as clayshales, are subject to earthflows that control hillslope morphology and supply sediments to the channel network. In this paper, we evaluate the sediment flux generated by earthflows and compare it with Holocene-averaged deposition rates to assess the contribution of mass movements to landscape evolution. Present-day hillslope sediment flux is estimated by combining measured displacement rates (72 inclinometers) and spatial attributes of earthflows and historical frequency of reactivations. Averaged sediment yield (~1.6x103 t/km2/yr) compares well with similar studies on earthflow-dominated landscapes, despite notable differences in methodology. In the study area, the connectivity between hillslopes and the stream network is well developed and no significant sediment sinks influence the sediment transport processes. We document best estimates of regional sediment fluxes and related uncertainties, based on available data. Coarse limestone fragments, present in the clayshales, are used as a natural sediment tracer to allow a comparison with sedimentation rates taking place at the mouth of the intramontane catchment. Here, available borehole logs, 14C datings and stratigraphic correlations of the alluvial fan are used to obtain an estimate of the deposition that took place during Holocene times. Taking also into account the role of solute transport, sedimentation rates are compared to earthflow sediment production rates. Results show a good agreement and demonstrate that earthflows are the primary mass wasting process in these weak rock lithologies. We document best estimates of regional sediment fluxes and related uncertainties. Present earthflow sediment production outpaces Holocene-averaged sedimentation rates by a factor of two. The gap between sediment production and deposition can be partly justified by uncertainties associated with our estimates and by time-scale differences. With this respect, the dynamic equilibrium between erosion and deposition, is likely affected by intra-Holocene oscillations at a short time scale (10 to 1ky) attributable to climate variability. Terraced deposits documenting sedimentary episodes would also support such interpretation. [Copyright &y& Elsevier]

Abstract: The study of cave clastic sediments has been considered one of the hottest topics during the last years because of their importance in paleoclimatic reconstructions and archaeological surveys. This paper focuses on clastic deposits of the Mugnano Cave, a small cave located in the Siena district (Northern Apennines, Italy), showing unique features regarding the sedimentary fill, mostly made of grey-blue dolomitic silts. The sedimentary succession was investigated through a detailed sedimentological analysis aimed at a better understanding of sedimentary processes active during the deposition. The entire succession was subsequently reinterpreted through an allostratigraphic approach: the recognition of an important erosional surface, associated with a significant change in sedimentation, allowed the distinguishing of two main allounits labelled MG1 and MG2. Furthermore, the different kinds of sediments collected in the cave were analysed using the XRF and XRD techniques, in order to establish their chemical and mineralogical compositions. The integration of lithological, sedimentological, allostratigraphic and mineralogical data permits formulation of an interesting hypothesis about speleogenetic processes that influenced the cave, with particular reference to the processes capable of generating the underground space. In this context, most of the current available space results from a complex interplay between different processes: disintegration of a particular lithofacies of the bedrock, consequent production of sediments and deposition into a subterranean lake. These sediments were removed from the cave during some non-depositional and erosive phases, which led to a positive balance in the available space. [Copyright &y& Elsevier]

Abstract: This paper describes the results of a rockfall hazard assessment for the village of San Quirico (Abruzzo region, Italy) based on an engineering-geological model. After the collection of geological, geomechanical, and geomorphological data, the rockfall hazard assessment was performed based on two separate approaches: i) simulation of detachment of rock blocks and their downhill movement using a GIS; and ii) application of geostatistical techniques to the analysis of georeferenced observations of previously fallen blocks, in order to assess the probability of arrival of blocks due to potential future collapses. The results show that the trajectographic analysis is significantly influenced by the input parameters, with particular reference to the coefficients of restitution values. In order to solve this problem, the model was calibrated based on repeated field observations. The geostatistical approach is useful because it gives the best estimation of point-source phenomena such as rockfalls; however, the sensitivity of results to basic assumptions, e.g. assessment of variograms and choice of a threshold value, may be problematic. Consequently, interpolations derived from different variograms have been used and compared among them; hence, those showing the lowest errors were adopted. The data sets which were statistically analysed are relevant to both kinetic energy and surveyed rock blocks in the accumulation area. The obtained maps highlight areas susceptible to rock block arrivals, and show that the area accommodating the new settlement of S. Quirico Village has the highest level of hazard according to both probabilistic and deterministic methods. [Copyright &y& Elsevier]

Abstract: This paper re-evaluates the origin of some peculiar patterns of ground deformation in the Central Apennines, observed by space geodetic techniques during the two earthquakes of the Colfiorito seismic sequence on September 26th, 1997. The surface displacement field due to the fault dislocation, as modelled with the classic Okada elastic formulations, shows some areas with high residuals which cannot be attributed to non-simulated model complexities. The residuals were investigated using geomorphological analysis, recognising the geologic evidence of deep-seated gravitational slope deformations (DSGSD) of the block-slide type. The shape and direction of the co-seismic ground displacement observed in these areas are correlated with the expected pattern of movement produced by the reactivation of the identified DSGSD. At least a few centimetres of negative “Line of Sight” ground displacement was determined for the Costa Picchio, Mt. Pennino, and Mt. Prefoglio areas. A considerable horizontal component of movement in the Costa Picchio DSGSD is evident from a qualitative analysis of ascending and descending interferograms. The timing of the geodetic data indicates that the ground movement occurred during the seismic shaking, and that it did not progress appreciably during the following months. This work has verified the seismic triggering of DSGSD previously hypothesized by many researchers. A further implication is that in the assessment of DSGSD hazard seismic input needs to be considered as an important cause of accelerated deformation. [Copyright &y& Elsevier]

Sinkholes are widely found in Italy in both carbonate slopes and alluvial plain settings. Since they may occur catastrophically, without showing premonitory signs and resulting in severe economic losses and casualties, they constitute a significant risk in many areas, and even pose a threat to human life. In this paper, we carried out a detailed multidisciplinary study of the Fossa San Vito sinkhole (southern Italy) that is a particular type of cover collapse sinkhole. The latter is a sub-circular, closed depression, with a diameter of ~200 m and with inner walls up to 25 m high, located in the piedmont area placed along the inner border of the Sarno River alluvial plain. The study entailed morphological and stratigraphic analysis by means of field surveys, including nine trenches, four boreholes, and the reinterpretation of stratigraphical data from the literature. In addition, hydrogeological and soil gas analysis were carried out to investigate the possible role of deep-water uprising. The study attempted to identify the genetic mechanism and include the reconstruction of a detailed subsurface stratigraphic model, showing that the infilling of the depression is about 45 m thick and consists of well-laminated, silty-clay lacustrine sediments interbedded with tephra layers. 14C dating of fossil wood found at the base of the lacustrine deposits constrains the age of the collapse at 5483 cal. years B.P. The collapse of the topographic surface involved a volume of about 400,000 cubic metres and originated at depth >80 m. Unlabelled Image • This study describes a peculiar type of cover collapse sinkhole. • The sinkhole has a diameter of ~200 m and is, at least, 65 m deep. • 14C dating constrains the age of the collapse at ~5483 cal. yr B.P. • The sinkhole was occupied by a lake and filled in by 40 m thick silts and clays. • The void responsible for the collapse formed by subsurface erosion at the rockhead [ABSTRACT FROM AUTHOR]