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Passaro S.,CNR Institute for Coastal Marine Environment | Milano G.,Osservatorio Vesuviano INGV | Sprovieri M.,CNR Institute for Coastal Marine Environment | Ruggieri S.,CNR Institute for Coastal Marine Environment | Marsella E.,CNR Institute for Coastal Marine Environment
Quaternary International | Year: 2011

A high-resolution morphological and geological inspection was carried out on the Palinuro Bank (39° 30′N, 14° 48′E), a volcanic complex made by several, coalescent volcanic features located on the Campanian continental slope (Eastern Tyrrhenian Sea, Italy). A shallow (-84 m asl) volcanic edifice, characterized by a flat top modelled surface, is present on its central sector. The use of a very high-resolution Digital Terrain Model allowed recognition of the presence of relict morphologies (perhaps notches/inner margins) related to the past sea-level still-stands. Three depth levels of paleo-shorelines markers are located at -90 m, -100 m, and -123 m, respectively. In addiction, the truncated shape of the cone itself, located between -84 m and -130 m, could be interpreted as a tilted marine terrace. Breaks in slope produced by terrace landforms caused oversteepening that could have triggered lateral collapses both on the northern and southern flanks of the Bank, as suggested by the presence of steep slopes (25-40°) and indicated by acoustic facies on chirp high-resolution mono-channel seismic profiles. The results allow further hypotheses on vertical displacement between the western sector of the Palinuro Bank, where caldera shapes are present, and the central sector, made by shallower volcanic cones. These two sectors also differ in terms of magnetic properties. © 2010 Elsevier Ltd and INQUA.

Milano G.,Osservatorio Vesuviano INGV | Passaro S.,CNR Institute for Coastal Marine Environment | Sprovieri M.,CNR Institute for Coastal Marine Environment
Bollettino di Geofisica Teorica ed Applicata | Year: 2012

In this paper, we present an overview of the Palinuro volcanic complex, in order to have a general outline of the main studies carried out on this seamount. The morphobathymetric studies show that the Palinuro volcanic complex rises from 3000 to 84 m b.s.l., extending about 55 km in the N100°E and 25 km in the N-S direction. The volcanic complex consists of several superimposed volcanic edifices that are basally connected to form a continuous volcanic ridge. Morphological evidence and magnetic data highlight the fact that the seamount is set on the northern edge of the Marsili Basin at the border between the oceanic basin and the continental shore. The presence of volcanic cones in the central sector, one of which shows a pronounced rim not obliterated by erosional events, the major amplitude of the magnetic anomalies with respect to the other sectors and the age of the products sampled on the summit, suggest that this sector is the youngest of the volcanic complex. Morphostructural, hydrothermal and magnetic data suggest that the south-eastern sector of the seamount could be active. The main fault affecting the summit (N65°E) and the E-W deepseated, strike-slip fault system, where the formation of the volcanic complex is hypothesized, may represent the expression of two tectonic lineaments on the seamount, E-W and NE-SW striking, of the Calabrian Arc. © 2012-OGS.

Mele D.,University of Bari | Dioguardi F.,University of Bari | Dellino P.,University of Bari | Isaia R.,Osservatorio Vesuviano INGV | And 2 more authors.
Journal of Volcanology and Geothermal Research | Year: 2015

Pyroclastic density currents of the recent eruptions at Campi Flegrei Caldera (CFC - Southern Italy) have been studied with the aim of assessing the potential impact of similar events in the future. Eruptions of different scales have been investigated by means of the combined use of facies architecture, laboratory analysis and physical modeling. Both in the small (Averno 2) and intermediate (Astroni) scales, facies analysis indicates that deposits result from the emplacement of pyroclastic density currents like base-surge, formed by multiple closely-timed impulses of phreatomagmatic origin. In the large-scale event (Agnano-Monte Spina), the facies architecture suggests that the currents started as concentrated flows near the vent, as originating from the collapse of a dense eruptive column, and evolved laterally into expanded flows by the propagation of the basal shear current. Laboratory analyses on samples from the main layers of deposits allowed obtaining the input data for the PYFLOW code, which was used for reconstructing the flow dynamic characteristics of the currents. The expected damage is discussed in terms of the probability density function of dynamic pressure and particle volumetric concentration. In this way, the range of potential impact that similar pyroclastic density currents could cause to buildings, infrastructures and population is defined.In the large-scale event, the dynamic pressure ranges from 9.38 to 1.00. kPa (integrating the basal 10. m of the current) at distances of 1.5 and 4.0. km from the vent, respectively. The values are highly influenced by the local topography. In the intermediate-scale event, the dynamic pressure ranges from 2.43 to 0.26. kPa at distances of 1.1 and 1.4. km from the vent, respectively. In the small scale event, the dynamic pressure ranges from 1.49 to 0.39. kPa at distances of 0.5 and 1.1. km from the vent, respectively.The particle volumetric concentration at a height of 2. m within the current is always lower than 0.01, but typically it is higher than 0.001 inside the caldera, and could have severe effects on the unsheltered population, also at locations (topographic highs) where velocity and dynamic pressures are low. In distal reaches outside the caldera the widespread fine ash originated by buoyancy from the currents, which was transported by lower atmosphere winds, is to be considered as a "fallout load" slowly accumulating on the ground surface (and building roofs) during the waning stage of the current. © 2015 Elsevier B.V.

Viveiros F.,University of The Azores | Cardellini C.,University of Perugia | Ferreira T.,University of The Azores | Caliro S.,Osservatorio Vesuviano INGV | And 2 more authors.
Journal of Geophysical Research: Solid Earth | Year: 2010

Carbon dioxide (CO2) diffuse degassing structures (DDS) at Furnas volcano (So Miguel Island, Azores) are mostly associated with the main fumarolic fields, evidence that CO2 soil degassing is the surface expression of rising steam from the hydrothermal system. Locations with anomalous CO2 flux are mainly controlled by tectonic structures oriented WNW-ESE and NW-SE and by the geomorphology of the volcano, as evidenced by several DDS located in depressed areas associated with crater margins. Hydrothermal soil CO2 emissions in Furnas volcano are estimated to be ∼968 t d-1. Discrimination between biogenic and hydrothermal CO2 was determined using a statistical approach and the carbon isotope composition of the CO2 efflux. Different sampling densities were used to evaluate uncertainty in the estimation of the total CO2 flux and showed that a low density of points may not be adequate to quantify soil emanations from a relatively small DDS. Thermal energy release associated with diffuse degassing at Furnas caldera is about 118 MW (from an area of ∼4.8 km2) based on the H2O/CO2 ratio in fumarolic gas. The DDS also affect Furnas and Ribeira Quente villages, which are located inside the caldera and in the south flank of the volcano, respectively. At these sites, 58% and 98% of the houses are built over hydrothermal CO 2 emanations, and the populations are at risk due to potential high concentrations of CO2 accumulating inside the dwellings. Copyright 2010 by the American Geophysical Union.

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