Numerical simulation of the tsunami generated by a past catastrophic landslide on the volcanic island of Ischia, Italy

The island of Ischia, Gulf of Naples, Italy, like many other volcanic islands is affected by mass failures, that are mainly related to secondary volcanic processes such as slope steepening and seismic shaking. The block resurgence of its main relief, Mount Epomeo, has been recognised to contribute cyclically to mass instability and cause landslides, that occasionally may reach the sea and start tsunamis. In this work we explore the consequences of the Ischia Debris Avalanche (IDA), a flank collapse that occurred in historical times, and involved the whole Mount Epomeo edifice including its submarine portion, and that may have caused gigantic sea waves affecting all the coasts of Ischia and of the Gulf of Naples. The IDA and the generated tsunami have been taken as the worst-case scenario for the occurrence of a new tsunami in the area. They have been simulated through numerical codes developed and maintained by the University of Bologna. The simulation shows that the IDA-induced tsunami attacks severely all the coasts of the Gulf of Naples with the highest waves obtained for the island of Ischia, the island of Capri and the peninsula of Sorrento. The propagation pattern of the IDA tsunami can be used to get hints on the impact that such an event may have had on early populations habiting Gulf of Naples, but also to get clues on the area that could be most severely hit by a tsunami generated by a smaller-scale landslide that may occur in the same source zone.     

Total content and chemical speciation of arsenic in the polychaete Sabella spallanzanii

An unusual feature has been observed in polychaetes regarding their capacity to accumulate high levels of relatively toxic forms of arsenic in specific tissues. Basal levels of arsenic and distribution of its compounds were investigated in tissues of the Mediterranean polychaete Sabella spallanzanii. Particularly high concentrations were measured in the branchial crown (1036+/-136 microg/g d.w.) and chemical speciation revealed that the predominant form was the relatively toxic dimethylarsinate (DMA). These data suggest a potential role of As as anti-predatory strategy in polychaetes.     

Analysis, synthesis and modelling of high-resolution observations of salt-marsh eco-geomorphological patterns in the Venice lagoon

The present paper describes observations, analyses and models of salt-marsh channel network and vegetation patterns with the aim of contributing to the development of predictive models of ecological and morphological co-evolution. Existing and new observations are described, with particular emphasis on remote sensing and ancillary field surveys, which are shown to allow reliable, accurate and repeatable quantitative characterizations of landform and vegetation properties over the spatial scales of interest. The observed channel network morphological characters are then used as the basis and validation of models describing the emergence of channel network and vegetation spatial patterns. In particular, with reference to observations performed in the Venice Lagoon, the note describes: (i) new, 2-cm resolution, characterizations of channel network geometry obtained from “proximal sensing” photographic observations; (ii) the reliable quantitative maps of salt-marsh vegetation which may be retrieved from hyperspectral remote sensing data and field ancillary observations; (iii) a synthesis of recent and new analyses of the statistical properties of vegetation and landform spatial organization, that may be inferred from the maps so derived; (iv) recent and new conceptual and quantitative ecological and geomorphic models developed and validated by remote-sensing and field observations. A coherent observational and theoretical eco-morphodynamic framework is then proposed.     

Remote sensing of Mercury's magnetospheric plasma environment via energetic neutral atoms imaging

The potentiality of exploring the plasma dynamical behavior of Mercury via energetic neutral atom (ENA) analysis is briefly discussed. The analysis of the Hermean ENA would give clues to the global magnetospheric configuration, clarifying crucial issues like the existence of radiation belts. In order to demonstrate the feasibility of ENA imaging in the Hermean environment, an empirical model of the equatorial proton distributions, originally developed for the Earth's magnetosphere, is here modified in order to be applicable to the expected conditions, according to the present knowledge of the planet. Simulations of the ENA radiation are then presented and discussed. It is shown that the simulated radiation is significantly high, especially when pointing the field of view towards the Hermean surface. The way of determining the proton flux distributions and the cross-tail electric field characteristics by using the ENA signal is discussed. Finally, a preliminary design of an ENA detector suitable for the ESA mission to Mercury ‘BepiColombo’ is proposed and discussed.     

Biosedimentary record of postglacial coastal dynamics: high‐resolution sequence stratigraphy from the northern Tuscan coast (Italy)

Integrating analysis of the benthic palaeoecological record with multivariate ordination techniques represents a powerful synergy able to provide an improved characterization of coastal depositional facies in a sequence stratigraphical perspective. Through quantitative analysis of benthic foraminifer, ostracod and mollusc associations from the postglacial succession of Core M3 (Arno coastal plain, Tuscany, Italy), and application of detrended correspondence analysis (DCA) to the mollusc sub‐data set, we offer a refined picture of stratigraphical variations in faunal content from a paralic depositional setting, and reconstruct the palaeoenvironmental gradients that account for such variations. Despite distinct ecological behaviours, and taphonomic and sedimentological constraints, a strong ecological control on meio‐ and macrofaunal biofacies and taxa turnover is documented across the study succession. Amongst all possible mechanisms that may play a role in ‘shaping’ fossil distribution, the ecological signal driven by salinity represents the most prominent factor controlling the composition of fossil associations in the cored succession. Molluscs can even provide outstanding quantitative estimates of palaeosalinity along the sampled core. When plotted stratigraphically, the three fossil sub‐data sets show consistent patterns of vertical evolution that enable prompt identification of the key surfaces for sequence stratigraphical interpretation in otherwise lithologically indistinguishable deposits. The concomitant maximum richness of species with strong marine affinity, paralleled by the highest DCA salinity estimates, allows recognition of the maximum flooding zone, dated to ～7.7 cal. ka BP, within a homogeneous succession of outer lagoon clays. These clays are sandwiched between early transgressive, swamp to inner lagoon deposits and overlying prograding coastal?alluvial plain facies.     

Palynology of Triassic–Jurassic boundary sections in northern Switzerland

A first palynostratigraphic scheme of Upper Triassic deposits in northern Switzerland was established based on spore-pollen associations and dinoflagellate cyst records from the upper part of the Upper Triassic Klettgau Formation and the lower part of the Lower Jurassic Staffelegg Formation. Drill cores from the Adlerberg region (Basel Tabular Jura) and from Weiach (northern part of Canton Zurich) as well as from an outcrop at the Chilchzimmersattel (Basel Folded Jura) were studied and five informal palynological associations are distinguished. These palynological associations correlate with palynological association of the Central European Epicontinental Basin and the Tethyan realm and provide a stratigraphic framework for the uppermost Triassic sediments in northern Switzerland. Throughout the uppermost Triassic to Jurassic palynological succession a remarkable prominence of Classopollis spp. is observed. Besides Classopollis spp. the three Rhaetian palynological associations A to C from the Upper Triassic Belchen Member include typical Rhaetian spore-pollen and dinoflagellate taxa (e.g., Rhaetipollis germanicus, Geopollis zwolinskae, Rhaetogonyaulax rhaetica, and Dapcodinium priscum). Association B differs from association A in a higher relative abundance of the sporomorph taxa Perinopollenites spp. and the consistent occurrence of Granuloperculatipollis rudis and Ricciisporites tuberculatus. Spore diversity is highest in the late Rhaetian palynological association C and includes Polypodiisporites polymicroforatus. A Rhaetian age for the Belchen Member is confirmed by palynological associations A–C, but there is no record of the latest Rhaetian and the earliest Jurassic. In contrast to the Rhaetian palynological associations the Early Jurassic associations W and D include Pinuspollenites spp., Trachysporites fuscus (in association W), and Ischyosporites variegatus. In the view of the end-Triassic mass extinction and contemporaneous environmental changes the described palynofloral succession represents the pre-extinction phase (associations A and B) including a distinct transgression, the extinction phase (association C) associated with a regression, and the post-extinction phase (association W).     

Evaluating soil erosion by water in a small alpine catchment in Northern Italy: comparison of empirical models

Acta Geochimica - To quantify water erosion rates and annual soil loss in mountainous areas, two different empirical models were used to estimate the effects of soil erosion in a small mountain...