The first ultra-high resolution Digital Terrain Model of the shallow-water sector around Lipari Island (Aeolian Islands, Italy)

Very high resolution bathymetric map obtained through multibeam echosounders data are crucial to generate accurate Digital Terrain Models from which the morphological setting of active volcanic areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the island of Lipari, the largest and the most densely populated of the Aeolian Islands (southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultrahigh resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters

Acquisizione magnetica marina dell\u27alto strutturale del Mt. Vercelli (Mar Tirreno Centrale) e del golfo di Napoli: descrizione dei rilievi e primi risultati

Durante la Campagna Oceanografica Ver2010, effettuata nel mese di maggio 2010, sono stati acquisiti due set di dati geomagnetici marini in alta risoluzione relativi alle aree del Mt. Vercelli (Mar Tirreno Centrale) e del Golfo di Napoli. Tale attività di misura è stata resa possibile grazie alla collaborazione tecnica scientifica tra l’Unità di Progetto “Geofisica e Tecnologie Marine” dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV) e l’Istituto Idrografico della Marina (IIM). La proficua collaborazione è sancita dall’accordo di cooperazione “Co.Na.Ge.M” (Coordinamento Nazionale per la Geofisica Marina). Nello specifico, i due rilievi sono stati svolti mediante l’impiego della Nave Idro-oceanografica “Aretusa”, unità navale dell’Istituto Idrografico della Marina con scafo a catamarano in vetroresina e, pertanto, particolarmente adatta a rilievi di tipo geomagnetico. L’attività di acquisizione geofisica del Monte Vercelli rientra nel Progetto TySec – Prin 2007 che coinvolge l’Università degli Studi di Genova, l’Università Politecnica delle Marche e l’Istituto Nazionale di Geofisica e Vulcanologia. L’obiettivo del progetto è quello di valutare le relazioni tra le caratteristiche morfologiche e idrodinamiche dell’area del seamount e l’ecosistema ad esso correlato. In questo lavoro proponiamo i risultati preliminari del survey geomagnetico e batimetrico della struttura sommersa del Vercelli

Multibeam bathymetry of Lipari island

Very high resolution bathymetric map obtained through multibeam echo-sounders data are crucial to generate accurate Digital Elevation Terrain Models from which the morphological setting of active volcanic areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the Island of Lipari, the largest and the most densely populated of the Aeolian islands (Southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultra-high resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters

The size of electron-hole pairs in pi conjugated systems

We have performed momentum dependent electron energy-loss studies of the electronic excitations in sexithiophene and compared the results to those from parent oligomers. Our experiment probes the dynamic structure factor S(q,omega)and we show that the momentum dependent intensity variation of the excitations observed can be used to extract the size of the electron-hole pair created in the excitation process. The extension of the electron-hole pairs along the molecules is comparable to the length of the molecules and thus maybe only limited by structural constraints. Consequently, the primary intramolecular electron-hole pairs are relatively weakly bound. We find no evidence for the formation of excitations localized on single thiophene units.Comment: RevTex, 3 figures, to appear in Physical Review Letter

Aggiornamento tecnologico e test funzionali del gravimetro da fondo LaCoste&Romberg modello U-HG24

Nel presente lavoro viene descritto l’aggiornamento tecnologico, effettuato in collaborazione con la società Tecnomare SpA, di un gravimetro da fondo LaCoste & Romberg modello U, serie H (numero HG24), di proprietà dell'Istituto Nazionale di Geofisica e Vulcanologia. Sono inoltre descritti e brevemente discussi i primi test in laboratorio ed i risultati di misure gravimetriche di fondo mare effettuate dal 19 al 22 Luglio 2010 nell'Area Marina Protetta del Parco Nazionale delle Cinque Terre. L'acquisizione di dati gravimetrici rientrava nelle attività specifiche del progetto di ricerca InSAS promosso e finanziato da eni Spa. La campagna a mare InSAS si è svolta in collaborazione con il NURC (NATO Undersea Research Centre) utilizzando come vettore marino il Coastal Research Vessel (CRV) ‘Leonardo’. Contestualmente all'attività di misure di gravità di fondo, sono stati acquisiti ed elaborati dal Politecnico di Milano diversi set di dati interferometrici Synthetic Aperture Sonar (SAS) su alcuni riflettori attivi e passivi localizzati nell'area di indagine. La campagna di misure a mare è stata preceduta da una serie di test in laboratorio al fine di valutare la piena funzionalità dello strumento in esame. In questa fase sono state acquisite diverse serie temporali allo scopo di valutare la qualità della misura e la sua ripetibilità

A time-temperature integrator based on fluorescent and polymorphic compounds

Despite the variety of functional properties of molecular materials, which make them of interest for a number of technologies, their tendency to form inhomogeneous aggregates in thin films and to self-organize in polymorphs are considered drawbacks for practical applications. Here, we report on the use of polymorphic molecular fluorescent thin films as time temperature integrators, a class of devices that monitor the thermal history of a product. The device is fabricated by patterning the fluorescent model compound thieno(bis)imide-oligothiophene. The fluorescence colour of the pattern changes as a consequence of an irreversible phase variation driven by temperature, and reveals the temperature at which the pattern was exposed. The experimental results are quantitatively analysed in the range 20–200°C and interpreted considering a polymorph recrystallization in the thin film. Noteworthy, the reported method is of general validity and can be extended to every compound featuring irreversible temperature-dependent change of fluorescence

The tsunamigenic potential of landslide-generated tsunamis on the Vavilov seamount

The investigation of submarine volcanoes and the tsunamigenic potential of possible movements on their flanks is arduous. In most cases, the lack of specific information about the eruptions’ history and their consequences does not allow a comprehensive analysis in terms of hazard. Nevertheless, useful clues on the possible occurrence of mass movements on seamounts can be obtained from a series of research fields. These account for morphological studies, observations of hydrothermal activity, collection of geophysical data (for example, detailed DEM, seismic profiles, magnetic data), etc. In this context, this study presents new bathymetric data of the Vavilov submarine volcano (Tyrrhenian Sea, Italy) and a detailed morphological analysis of the structure. The latter allows the identification of zones potentially prone to mass movements and the development of numerical scenarios to investigate the tsunami potential associated to these movements on the Vavilov flanks. Results prove that the waves generated by the mass displacements in the proposed scenarios (involving sliding volumes between 0.32 km3 and 1.7 km3) reach maximum values in the order of centimetres, not considering dispersive effects. Eventually, a scenario involving the partial collapse of the west flank of the Vavilov Seamount is simulated, although the occurrence of such an event in the past is still debated due to the uncertainties related to the origin and development of the volcano dome. In this scenario, water elevation as high as 10 m are found in large portions of the Tyrrhenian coasts: waves are large enough to emplace sizeable tsunami deposits onshore, that could have been preserved until today in some specific stretches of the coast and could be detected by a finalised geological search. This study belongs to a series of works devoted to the submarine structures of the Tyrrhenian Sea aiming to disclose the tsunamigenic potential of submarine mass movements on their flanks

Genesis of oceanic oxide gabbros and gabbronorites during reactive melt migration at transform walls (Doldrums Megatransform System; 7-8°N Mid-Atlantic Ridge)

The Doldrums Megatransform System (~7-8°N, Mid-Atlantic Ridge) shows a complex architecture including four intra-transform ridge segments bounded by five active transform faults. Lower crustal rocks are exposed along the Doldrums and Vernadsky transform walls that bound the northernmost intra-transform ridge segment. The recovered gabbros are characterized by variably evolved chemical compositions, ranging from olivine gabbros to gabbronorites and oxide gabbros, and lack the most primitive gabbroic endmembers (troctolites, dunites). Notably, the numerous recovered gabbronorites show up to 20 vol% of coarse-grained orthopyroxene. Although covariations in mineral and bulk-rock chemical compositions of the olivine and oxide gabbros define trends of crystallization from a common parental melt, the gabbronorites show elevated light over heavy rare earth elements (LREE/HREE) ratios in both bulk-rock and mineral compositions. These features are not consistent with a petrological evolution driven solely by fractional crystallization, which cannot produce the preferential enrichments in highly incompatible elements documented in the orthopyroxene-bearing lithologies. We suggest that gabbronorites crystallized from evolved melts percolating and partly assimilating a pre-existing olivine gabbro matrix. Saturation in orthopyroxene and selective enrichments in LREE relative to M-HREE are both triggered by an increase in assimilated crystal mass, which ranges from negligible in the oxide-gabbros to abundant in the gabbronorites. This melt-rock reaction process has been related to lateral melt migration beneath ridge-transform intersections, where variably evolved melts injected from the peripheral parts of the melting region towards the transform zone may interact with a gabbroic crystal mush to form abundant oxide-bearing gabbronoritic associations

Multidisciplinary Investigations at Panarea (Aeolian Islands) after the Exhalative Crisis of 2002

Panarea and surrounding Islets form a volcanic edifice, that is part of the Eastern sector of the Aeolian Arc, Southern Tyrrhenian Sea. It is now considered inactive, since last documented activity is 20 Ka old. However, on 2002-11-03, gas started to flow violently from the seafloor in an area E of the Island, mainly along NE and NW structural lineaments, and lasting up to 2003-2004 with a consistent flux, orders of magnitude larger that ’steady-state’ fumarolic activity documented there in historical times. On the same period a strong effusive activity of Stromboli (10 NM to NNE) was present. Since then, several investigations have been conducted at sea and on land, with the aim of focusing on the problem of effusive activity at sea, mainly in the light of volcanic surveillance and risk. Among these investigations, some of which have been repeated over years, we present and discuss some data and results from: (a)visual inspection and sampling by divers and ROV, (b)GPS networks and mapping by multibeam and LIDAR, (c) oceanographical measurements by current meters and CTD, and water flux and dynamics measurements, (d)magnetic and gravimetric surveys, (e) multichannel reflection Seismic with OBS and land station networks. Data were used for compilation of high resolution bathymetric, magnetic and gravimetric maps, including the emerged and submerged portions of the edifice

Multidisciplinary Investigation at Panarea (Aeolian Islands) After the Exhalative Crisis of 2002.

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