Morpho-structural setting of Stromboli volcano revealed by high-resolution bathymetry and backscatter data of its submarine portions   总被引：1，自引：0，他引：1  

Alessandro Bosman  Francesco L. Chiocci  Claudia Romagnoli 《Bulletin of Volcanology》2009,71(9):1007-1019

The first high-resolution bathymetric and backscatter maps of offshore Stromboli Island are presented, together with an interpretation of its volcanic, structural and sedimentary features. The volcanic edifice is characterized by a sub-conical shape with a quasi-bilateral symmetry with respect to a NE-SW axis. The dimensions of the Strombolicchio volcanic centre, to the NE of Stromboli, have been restored by redrawing its morphology before wave action that eroded it in Late Quaternary time. On the NE submarine flank of Strombolicchio, a N64°E structural trend controls the shape of Strombolicchio Canyon. On the southern side of Stromboli, the submarine flank has a radial structural trend, possibly reflecting a volcanic stress regime. Landslide scars at various scales are ubiquitous on the submarine slopes of Stromboli. Repeated large-scale lateral collapses have affected both the northwestern and southeastern unbuttressed flanks of the volcano, producing large debris avalanche deposits.  相似文献   

Age and whole rock–glass compositions of proximal pyroclastics from the major explosive eruptions of Somma-Vesuvius: A review as a tool for distal tephrostratigraphy     

Roberto Santacroce  Raffaello Cioni  Paola Marianelli  Alessandro Sbrana  Roberto Sulpizio  Giovanni Zanchetta  Douglas J. Donahue  Jean Louis Joron 《Journal of Volcanology and Geothermal Research》2008

A review of compositional data of the major explosive eruptions of Vesuvius is presented, comparing compositions (major elements) of whole rock with glass shards from the proximal deposits, hopefully useful for long-distance correlation. A critical review of published and new geochronological data is also provided. All available ¹⁴C ages are calibrated to give calendar ages useful for the reconstruction of the volcanological evolution of the volcanic complex. The pyroclastic deposits of the four major Plinian eruptions (22,000 yr cal BP “Pomici di Base”, 8900 yr cal BP “Mercato Pumice”, 4300 yr cal BP “Avellino Pumice”, and A.D. 79 “Pompeii Pumice”) are widely dispersed and allow a four-folded, Plinian to Plinian, stratigraphic division: 1. B–M (between Pomici di Base and Mercato); 2. M–A (between Mercato and Avellino); 3. A–P (between Avellino and Pompeii); 4. P–XX (from the Pompeii Pumice to the last erupted products of the XXth century). Within each interval, the age, lithologic and compositional features of pyroclastic deposits of major eruptions, potentially useful for tephrostratigraphic purposes on distal areas, are briefly discussed. The Vesuvius rocks are mostly high Potassic products, widely variable in terms of their silica saturation. They form three groups, different for both composition and age: 1. slightly undersaturated, older than Mercato eruption; 2. mildly undersaturated, from Mercato to Pompeii eruptions; 3. highly undersaturated, younger than Pompeii eruption. For whole rock analyses, the peculiar variations in contents of some major and trace elements as well as different trends in element/element ratios, allow a clear, unequivocal, easy diagnosis of the group they belong. Glass analyses show large compositional overlap between different groups, but selected element vs. element plots are distinctive for the three groups. The comparative analysis of glass and whole rock major element compositions provides reliable geochemical criteria helping in the recognition, frequently not obvious, of distal products from the different single eruptions.  相似文献   

Contractional tectonics and magma paths in volcanoes     

Alessandro Tibaldi 《Journal of Volcanology and Geothermal Research》2008

This study aims to contribute a possible explanation for magma migration within volcanoes located in contractional tectonic settings, based on field data and physically-scaled experiments. The data demonstrate the occurrence of large stratovolcanoes in areas of coeval reverse faulting, in spite of the widely accepted idea that volcanism can develop only in extensional/transcurrent tectonic settings. The experiments simulate the propagation of deformation from substrate reverse faults with different attitudes and locations into volcanoes. The substrate fault splits into two main shear zones within the volcano: A shallow-dipping one, with reverse motion, propagates towards the lower volcano flank, and a steeper-dipping one, with normal motion, propagates upwards. In plan view, the reverse fault zone is arcuate and convex outwards, whereas the normal fault zone is rectilinear. Structural field surveys at volcanoes located in contractional settings show similar features: The Plio–Quaternary Trohunco and Los Cardos–Centinela volcanic complexes (Argentina) lie above Plio–Quaternary reverse faults. The Late Pleistocene–Holocene El Reventador volcano (Ecuador) is also located in a coeval contractional tectonic belt. These volcanoes show curvilinear reverse faults along one flank and rectilinear extensional fracture zones across the crater area, consistent with the experiments. These data consistently suggest that magma migrates along the substrate reverse fault and is channelled along the normal fault zone across the volcano.  相似文献   

High‐pressure mineral assemblage in granitic rocks from continental units,Alpine Corsica,France     

Alessandro Malasoma  Michele Marroni  Giovanni Musumeci  Luca Pandolfi 《Geological Journal》2006,41(1):49-59

The Popolasca–Francardo area of northern Corsica contains an assemblage of continental tectonic units affected by an Alpine deformation. In one of these units, Unit II, previously regarded as weakly metamorphosed, a metamorphic mineral assemblage characterized by sodic amphibole, phengite, quartz, albite and epidote has been found in an aplite dyke that cuts the dominant granitoids. Peak‐metamorphic temperature and pressure conditions of 300–370°C and 0.50–0.80 GPa, respectively, have been determined. This finding indicates that a continuous belt of continental slices, characterized by high‐pressure, low‐temperature metamorphism of Tertiary age, extends from the Tenda Massif in the north to the Corte area in the south, thus placing additional constraints on the tectonic evolution of Alpine Corsica. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Sar Interferometry And Its Applications     

Fabio Rocca  Claudio Prati  Andrea Monti Guarnieri  Alessandro Ferretti 《Surveys in Geophysics》2000,21(2-3):159-176

Satellite mounted Synthetic Aperture Radars (SAR) provide informationof the amplitude of the backscatterer its phase. This corresponds to the totaltravel time (source receiver and back), plus the phase of the scatterer itself.SAR interferometry yields the image of the differences of the phases takenin two successive passes. Or in the same pass if two receivers are availableon board; these images give a good digital elevation model of the terrain,with a vertical resolution that could be in the meter range. Millimetric motionof large areas of the terrain or of corner reflectors can also be measured withgood reliability; the system then measures subsidence, co-seismic motions andsmall motions of buildings and constructions. The coherence of t e interferometric pair, i.e., the permanence of the scattering characteristics of the terrain from one pass to the next combined with the more usual backscatterer amplitude, leads to high quality image segmentation. The possibilities and the limits of this technique are summarized.  相似文献   

Reply to “Discussion 2 on ‘Introspection on improper seismic retrofit of Basilica Santa Maria di Collemaggio after 2009 Italian earthquake’ by G.P. Cimellaro, A.M. Reinhorn and A.De Stefano” by Enzo Cartapati     

Gian Paolo Cimellaro  Andrei M. Reinhorn  Alessandro De Stefano 《地震工程与工程振动(英文版)》2012,11(2):291-292

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Reply to “Discussion 2 on ‘Introspection on improper seismic retrofit of Basilica Santa Maria di Collemaggio after 2009 Italian earthquake' by G.P.Cimellaro, A.M.Reinhorn and A.De Stefano” by Enzo Cartapati     

Gian Paolo Cimellaro  Andrei M. Reinhorn  Alessandro De Stefano 《地震工程与工程振动(英文版)》2012,11(2):291-292

The authors thank the discusser for the additional information,which is provided related to the historical interventions of the church through the centuries.This information was known to the authors,however they decided not to include it in the paper because of lack of space.Additional details regarding the retrofit interventions of the church can also be found in the MCEER report regarding the L'Aquila earthquake (Cimellaro et al.,2010).  相似文献   

Observation of Hamiltonian chaos in wave–particle interaction     

Fabrice Doveil  Alessandro Macor  Anass Aïssi 《Celestial Mechanics and Dynamical Astronomy》2008,102(1-3):255-272

The motion of charged particle in longitudinal waves is a paradigm for the transition to large scale chaos in Hamiltonian systems. Recently a test cold electron beam has been used to observe its non-self-consistent interaction with externally excited wave(s) in a specially designed Traveling Wave Tube (TWT). The velocity distribution function of the electron beam is recorded with a trochoidal energy analyzer at the output of the TWT. An arbitrary waveform generator is used to launch a prescribed spectrum of waves along the slow wave structure (a 4 m long helix) of the TWT. The resonant velocity domain associated to a single wave is observed, as well as the transition to large scale chaos when the resonant domains of two waves and their secondary resonances overlap. This transition exhibits a “devil’s staircase” behavior when increasing the excitation amplitude in agreement with numerical simulation. A new strategy for control of chaos by building barriers of transport which prevent electrons to escape from a given velocity region as well as its robustness are also successfully tested. Thus generic features of Hamiltonian chaos have been experimentally observed.  相似文献   

Optical emission from massive donors in ultraluminous X-ray source binary systems     

Alessandro Patruno  Luca Zampieri 《Monthly notices of the Royal Astronomical Society》2008,386(1):543-552

We present evolutionary tracks of binary systems with high-mass companion stars and stellar-through-intermediate mass black holes (BHs). Using Eggleton's stellar evolution code, we compute the luminosity produced by accretion from the donor during its entire evolution. We compute also the evolution of the optical luminosity and colours of the binary system taking the disc contribution and irradiation effects into account. The calculations presented here can be used to constrain the properties of the donor stars in ultraluminous X-ray sources by comparing their position on the Hertzsprung–Russell or colour–magnitude diagrams with the evolutionary tracks of massive BH binaries. This approach may actually provide interesting clues also on the properties of the binary system itself, including the BH mass. We found that, on the basis of their position on the colour–magnitude diagram, some of the candidate counterparts considered can be ruled out and more stringent constraints can be applied to the donor masses.  相似文献   

Effects of the filtering action exerted by piles on the seismic response of RC frame buildings     

Luca de Sanctis  Raffaele Di Laora  Nicola Caterino  Giuseppe Maddaloni  Stefano Aversa  Alessandro Mandolini  Antonio Occhiuzzi 《Bulletin of Earthquake Engineering》2015,13(11):3259-3275

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