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  • 1
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    Italian and Alpine three-dimensional crustal structure imaged by ambient-noise surface-wave dispersion (2015)
    Wiley
    Details
    Publication Date: 2015-12-09
    Description: We derive the 3D crustal structure (S wave velocity) underneath Italy and the Alpine region, expanding and exploiting the database of ambient noise Rayleigh-wave phase- and group-velocity of verbeke et al . [2012]. We first complement the database of verbeke et al . [2012] with a dense set of new ambient-noise-based phase-velocity observations. We next conduct a suite of linear least squares inversion of both phase- and group-velocity data, resulting in 2D maps of Rayleigh-wave phase and group velocity at periods between 5 and 37 s. At relatively short periods, these maps clearly reflect the surface geology of the region, e.g. low velocity zones at the Po Plain; at longer periods, deeper structures such as Moho topography under Alps and Apennines, and lower-crust anomalies are revealed. Our phase- and group-velocity models are next inverted via the Neighbourhood Algorithm to determine a set of one-dimensional shear-velocity models (one per phase/group-velocity pixel), resulting in a new three-dimensional model of shear velocity ( υ S ) parameterized in the same way as the European reference crustal model EPcrust [ Molinari and Morelli, 2011]. We also show how well υ S is constrained by phase and group dispersion curves. The model shows the low velocity area beneath the Po Plain and the Molasse basin; the contrast between the low-velocity crust of the Adriatic domain and the high-velocity crust of the Tyrrhenian domain is clearly seen, as well as an almost uniform crystalline crust beneath the Alpine belt. Our results are discussed from the geological/geodynamical standpoint, and compared to those of other, interdisciplinary studies. This article is protected by copyright. All rights reserved.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    The influence of non-uniform ambient noise on crustal tomography in Europe (2013)
    Wiley
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    Publication Date: 2013-03-02
    Description: [1]  Ambient-noise seismology is of great relevance to high-resolution crustal imaging, thanks to the unprecedented dense data coverage it affords in regions of little seismicity. Under the assumption of uniformly distributed noise sources, it has been used to extract the Green’s function between two receivers. We determine the imprint of this assumption by means of wave propagation and adjoint methods in realistic 3D Earth models. In this context, we quantify the sensitivity of ambient-noise cross correlations from central Europe with respect to noise-source locations and shear wavespeed structure. We use ambient noise recorded over one year at 196 stations, resulting in a database of 864 cross-correlations. Our mesh is built upon a combined crustal and 3D tomographic model. We simulate synthetic ambient-noise cross-correlations in different frequency bands using a 3D spectral-element method. Traveltime cross-correlation measurements in these different frequency bands define the misfit between synthetics and observations as a basis to compute sensitivity kernels using the adjoint method. We perform a comprehensive analysis varying geographic station and noise-source distributions around the European seas. The deterministic sensitivity analysis allows for estimating where the starting crustal model shows better accordance with our dataset and gain insight into the distribution of noise sources in the European region. This highlights the potential importance to consider localized noise distributions for tomographic imaging and forms the basis of a tomographic inversion in which the distribution of noise sources may be treated as a free parameter similar to earthquake tomography.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    A new dyke intrusion style for the Mount Etna May 2008 eruption modelled through continuous tilt and GPS data (2009)
    Wiley
    Details
    Publication Date: 2009-08-01
    Print ISSN: 0954-4879
    Electronic ISSN: 1365-3121
    Topics: Geosciences
    Published by Wiley
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  • 4
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    TINITALY/01: a new Triangular Irregular Network of Italy (2008)
    Editrice Compositori
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    Publication Date: 2019-11-04
    Description: A new Digital Elevation Model (DEM) of the natural landforms of Italy is presented. A methodology is discussed to build a DEM over wide areas where elevation data from non-homogeneous (in density and accuracy) input sources are available. The input elevation data include contour lines and spot heights derived from the Italian Regional topographic maps, satellite-based global positioning system points, ground based and radar altimetry data. Owing to the great heterogeneity of the input data density, the DEM format that better preserves the original accuracy is a Triangular Irregular Network (TIN). A Delaunay-based TIN structure is improved by using the DEST algorithm that enhances input data by evaluating inferred break-lines. Accordingly to this approach, biased distributions in slopes and elevations are absent. To prevent discontinuities at the boundary between regions characterized by data with different resolution a cubic Hermite blending weight S-shaped function is adopted. The TIN of Italy consists of 1.39×109 triangles. The average triangle area ranges from 12 to about 13000 m2 accordingly to different morphologies and different sources. About 50% of the model has a local average triangle area 〈500 m2. The vertical accuracy of the obtained DEM is evaluated by more than 200000 sparse control points. The overall Root Mean Square Error (RMSE) is less than 3.5 m. The obtained national-scale DEM constitutes an useful support to carry out accurate geomorphological and geological investigations over large areas. The problem of choosing the best step size in deriving a grid from a TIN is then discussed and a method to quantify the loss of vertical information is presented as a function of the grid step. Some examples of DEM application are outlined. Under request, an high resolution stereo image database of the whole Italian territory (derived from the presented DEM) is available to browse via internet.
    Description: Published
    Description: 407-425
    Description: 5.4. TTC - Sistema Informativo Territoriale
    Description: JCR Journal
    Description: open
    Keywords: Italy ; triangular irregular network ; DEM ; interpolation method ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    The 8th ICGG International Conference on Gas Geochemistry Preface: Fluids and tectonics (2008)
    Editrice Compositori
    Details
    Publication Date: 2019-11-04
    Description: introduction to the special issue: 8th international conference on gas geochemistry
    Description: The 8th International Conference on Gas Geochemistry provided the opportunity for scientists from different countries to meet each other, exchange ideas on the state of the art in gas geochemistry, and discuss advance in fluid geochemistry. The 8th ICGG meeting focused on three main geologic environments currently interacting with the human life: volcanoes, earthquakes and hydrocarbons. Ninety-four presentations gave participants chance to cover a variety of important research topics on gas geochemistry in geosciences including: gas migration in terrestrial and marine environments, Earth degassing and its relation to seismicity, volcanic eruptions, rare gases and application of isotope techniques, measurement and analytical techniques.
    Description: Published
    Description: V-IX
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: fluids ; Geochemistry ; tectonics ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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