A new hybrid procedure for the definition of seismic vulnerability in Mediterranean cross-border urban areas

Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called “hybrid.” Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model.

     

Hard coastal-defence structures as habitats for native and exotic rocky-bottom species

The use of hard coastal-defence structures, like breakwaters and seawalls, is rapidly increasing to prevent coastal erosion. We compared low-shore assemblages between wave-protected and wave-exposed habitats on breakwaters along a sandy shore of Tuscany (North-Western Mediterranean). Assemblages were generally characterized by a low diversity of taxa, with space monopolized by Mytilus galloprovincialis and Corallina elongata on the seaward side of breakwaters and by filamentous algae on the landward side. Assemblages in wave-protected habitats were characterized by greater temporal stability than those in exposed habitats and supported non-indigenous macroalgae such as Caulerpa racemosa and Codium fragile ssp. tomentosoides. Hence, the introduction of hard coastal-defence structures in otherwise soft-bottom dominated areas, attracting native and exotic rocky-bottom species, should be of great concern for the conservation of marine biodiversity at local and regional scales and for the management of biological invasions.     

Effects of enhanced loads of nutrients on epiphytes on leaves and rhizomes of Posidonia oceanica

The increase of anthropogenic activities has severely altered both terrestrial and aquatic systems. Urbanisation, excessive use of agricultural fertilisers, organic runoff and climate change have caused an increase of nutrients in coastal waters, altering the diversity and food-web structure of benthic assemblages. The aims of the present paper were to text if an experimentally increased availability of nutrients, primarily nitrogen and phosphorous, in an oligotrophic basin, would affect epiphytic assemblages on leaves and rhizomes of P. oceanica and whether this could change rates of consumption of the plant by herbivores. In particular, we tested the hypothesis i) that changes to species composition and abundance of epiphytic assemblages generated by nutrients enrichment would vary between leaves and rhizomes and that ii) alterations to epiphytic assemblages on leaves might, in turn, modify feeding rates of herbivorous fish. After two years, the structure of both leaf and rhizome epiphytic assemblages responded to changes in nutrient concentrations before the occurrence of drastic alterations to the host plant, but only the former showed significant changes in terms of species composition. Moreover, a larger intensity of grazing on P. oceanica leaves was documented in experimentally enriched areas than in controls. The present findings and conclusions are applicable to other systems where patterns of biodiversity depend on changes in the availability of nutrients due to natural or anthropogenic events, likely interacting with biological processes, such as competition and grazing.     

Discovery of cryptotephra at Middle–Upper Paleolithic sites Arma Veirana and Riparo Bombrini,Italy: a new link for broader geographic correlations

Chemical characterization of cryptotephra is critical for temporally linking archaeological sites. Here, we describe cryptotephra investigations of two Middle–Upper Paleolithic sites from north-west Italy, Arma Veirana and Riparo Bombrini. Cryptotephra are present as small (<100 µm) rhyolitic glass shards at both sites, with geochemical signatures rare for volcanoes in the Mediterranean region. Two chemically distinct shard populations are present at Arma Veirana (P1 and P2). P1 is a high silica rhyolite (>75 wt.%) with low FeO (<1 wt.%) and a K₂O/Na₂O > 1 and P2 is also a high silica rhyolite (>75 wt.%) but with higher FeO (2.33–2.65 wt.%). Shards at Riparo Bombrini (P3) are of the same composition as P1 shards at Arma Veirana, providing a distinct link between deposits at both sites. Geochemical characteristics suggest three possible sources for P1 and P3: eruptions from Lipari Island (56–37.7 ka) in Italy, the Acigöl volcanic field (200–20 ka) in Turkey and the Miocene Kirka-Phrigian caldera (18 Ma) in Turkey. Eruptions from Lipari Island are the most likely source for P1,3 cryptotephra. This study highlights how cryptotephra can benefit archaeology, by providing a direct link between Arma Veirana and Riparo Bombrini as well as other deposits throughout the Mediterranean.     

Statistical properties of dissipation bursts within turbulence: Solar flares and geomagnetic activity

We investigate some statistical properties of the solar soft X-ray flux and of the Auroral Electrojet (AE) index. For both these signals, the probability density functions (PDFs) of normalized differences are shown to display wide, non-Gaussian tails. The shape of the PDFs is nearly unchanged as the timelag, used to calculate differences, varies. Moreover, the two time series are characterized by a power-law distribution for waiting times between successive bursts and by a clear departure from an hypothesis of locally Poisson statistics. A similar behavior is found in a shell model of magnetohydrodynamic (MHD) turbulence.     

Seismic hazard in southern Calabria (Italy) based on the analysis of a synthetic earthquake catalog

The application of a newly developed physics-based earthquake simulator to the active faults inferred by aeromagnetism in southern Calabria has produced a synthetic catalog lasting 100 ky including more than 18,000 earthquakes of magnitude ≥?4.0. This catalog exhibits temporal, spatial and magnitude features, which resemble those of the observed seismicity. As an example of the potential use of synthetic catalogs, a map of the peak ground acceleration (PGA) for a given exceedance probability on the territory under investigation has been produced by means of a simple attenuation law applied to all the events reported in the synthetic catalog. This map was compared with the existing hazard map that is presently used in the national seismic building regulations. The comparison supports a strong similarity of our results with the values given in the present Italian seismic building code, despite the latter being based on a different methodology. The same similarity cannot be recognized for the comparison of our present study with the results obtained from a previous study based on our same methodology but with a different geological model.     

Active foreland deformation evidenced by shallow folds and faults affecting late Quaternary shelf–slope deposits (Adriatic Sea, Italy)

A succession of depositional sequences, recording middle-late Pleistocene and Holocene glacial–interglacial cycles, documents the impact of short-term tectonic deformation on the western Adriatic margin. The western Adriatic margin is part of the Apennine foreland which was intensely, though variably, deformed during the Meso-Cenozoic evolution of the Adriatic region from a passive margin to a foreland basin. The study area extends offshore Gargano Promontory, an uplifted sector of the Adriatic foreland, and includes three major deformation belts located along or cross-strike to the margin: (1) the NW-SE Gallignani-Pelagosa ridge, (2) the WSW-ENE Tremiti-Pianosa high (both located north of Gargano) and (3) the W-E to NW-SE Gondola fault deformation belt (in the south Adriatic). Long-term deformation along these tectonic lineaments is documented on conventional low-frequency seismic profiles by regional folds and faults affecting Eocene–Miocene units overlain by dominantly draping Plio-Quaternary deposits. At this scale of observation, only north of Gargano Promontory there is some evidence of Plio-Quaternary units thinning against structural highs, thus suggesting that tectonic deformation was protracted through this interval. Based on new high-resolution seismic data, we show that deformation along these pre-existing tectonic structures continued during the Quaternary, affecting middle-late Pleistocene and even Holocene units on the shelf and upper slope north and south of Gargano Promontory. These recent deformations consist of gentle folds and high-angle faults, locally producing topographic relief that affects the stratigraphy and thickness of syn-tectonic deposits. We interpret the small-scale, shallow faults and gentle folds affecting middle-late Pleistocene and Holocene deposits, north and south Gargano Promontory, as the evidence of ongoing foreland deformation along inherited regional fold and fault systems.     

Effects of the Magnetic Field on the Hα Emission from Jets

We present results of MHD axisymmetrical cylindrical simulations performed to study Hα emission maps from jets, with a toroidal field geometry for the magnetic field. Our code uses a linear Riemann solver, integrates equations in 2.5 dimensions and includes the calculation of the ionization fraction and the effects of the emission due to the collisional excitation of [O I] and [O II] lines, radiative recombination of H and the collisional ionization of H and excitation of Lyman-α. The simulations with variable ejection velocities show that the magnetic field produces an increase in the emission from all of the knots except for the first bow shock.     

意大利东北部晚三叠世一新翼龙

To date, the middle-late Norian Dolomia di Forni Formation of the Friuli region of NE Italy has yielded ten pterosaur specimens. They include the holotypes of Preondactylus buffarinii Wild, 1984 and Carniadactylus rosenfeldi (Dalla Vecchia, 1995) and a specimen referred to Austriadactylus cristatus Dalla Vecchia, Wild, Hopf & Reitner, 2002.