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  • 1
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    Gravity crustal models and heat flow measurements for the Eurasia Basin, Arctic Ocean (2009)
    Springer
    Details
    Publication Date: 2009-12-01
    Print ISSN: 0025-3235
    Electronic ISSN: 1573-0581
    Topics: Geosciences , Physics
    Published by Springer
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    PAPER CURRENT
  • 2
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    Gravity crustal models and heat flow measurements for the Eurasia Basin, Arctic Ocean (2009)
    Springer
    In:  Marine Geophysical Researches, 30 (4). pp. 277-292.
    Details
    Publication Date: 2018-06-12
    Description: The Gakkel Ridge in the Arctic Ocean with its adjacent Nansen and Amundsen Basins is a key region for the study of mantle melting and crustal generation at ultraslow spreading rates. We use free-air gravity anomalies in combination with seismic reflection and wide-angle data to compute 2-D crustal models for the Nansen and Amundsen Basins in the Arctic Ocean. Despite the permanent pack-ice cover two geophysical transects cross both entire basins. This means that the complete basin geometry of the world’s slowest spreading system can be analysed in detail for the first time. Applying standard densities for the sediments and oceanic crystalline crust, the gravity models reveal an unexpected heterogeneous mantle with densities of 3.30 × 103, 3.20 × 103 and 3.10 × 103 kg/m3 near the Gakkel Ridge. We interpret that the upper mantle heterogeneity mainly results from serpentinisation and thermal effects. The thickness of the oceanic crust is highly variable throughout both transects. Crustal thickness of less than 1 km dominates in the oldest parts of both basins, increasing to a maximum value of 6 km near the Gakkel Ridge. Along-axis heat flow is highly variable and heat flow amplitudes resemble those observed at fast or intermediate spreading ridges. Unexpectedly, high heat flow along the Amundsen transect exceeds predicted values from global cooling curves by more than 100%.
    Type: Article , PeerReviewed
    Format: text
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  • 3
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    Gravity crustal models and heat flow measurements for the Eurasia Basin, Arctic Ocean (2009)
    Springer
    In:  Marine Geophysical Researches, 30 (4). pp. 277-292.
    Details
    Publication Date: 2014-09-05
    Description: The Gakkel Ridge in the Arctic Ocean with its adjacent Nansen and Amundsen Basins is a key region for the study of mantle melting and crustal generation at ultraslow spreading rates. We use free-air gravity anomalies in combination with seismic reflection and wide-angle data to compute 2-D crustal models for the Nansen and Amundsen Basins in the Arctic Ocean. Despite the permanent pack-ice cover two geophysical transects cross both entire basins. This means that the complete basin geometry of the world’s slowest spreading system can be analysed in detail for the first time. Applying standard densities for the sediments and oceanic crystalline crust, the gravity models reveal an unexpected heterogeneous mantle with densities of 3.30 × 103, 3.20 × 103 and 3.10 × 103 kg/m3 near the Gakkel Ridge. We interpret that the upper mantle heterogeneity mainly results from serpentinisation and thermal effects. The thickness of the oceanic crust is highly variable throughout both transects. Crustal thickness of less than 1 km dominates in the oldest parts of both basins, increasing to a maximum value of 6 km near the Gakkel Ridge. Along-axis heat flow is highly variable and heat flow amplitudes resemble those observed at fast or intermediate spreading ridges. Unexpectedly, high heat flow along the Amundsen transect exceeds predicted values from global cooling curves by more than 100%.
    Type: Article , PeerReviewed
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  • 4
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    How does the geomorphometry of a volcanic island influence the stability of its flanks? (2022)
    Details
    Publication Date: 2022-03-23
    Description: Volcanic islands are known to be a source of many natural hazards associated with active volcanism. The processes leading to the instability of their flanks, however are less well understood. The movement of an instable volcanic flank occurs in either or both of two ways; slow sliding of several cm per year (i.e. Etna, Italy) and/or the catastrophic collapse of a large portion of the edifice (i.e. Anak Krakatau, Indonesia). The conditions and precursors leading to such events are often unknown. The limited availability of high-resolution bathymetry data especially at the coast is often restricting the quantitative geomorphological investigation to the subaerial part of the volcanic island. It is essential, however, to include the entire volcanic edifice as instability affects the volcano from summit to seafloor. In this study, we test whether and in which way, the morphology of the volcanic edifice affects its instability. We combine openly available high-resolution bathymetric and topographic grids (50-150m grid spacing) to create shoreline-crossing DEMs of volcanic islands in four areas (archipelagos of Hawaii, Canaries, Mariana Islands and South Sandwich Islands). Morphological parameters, such as area, volume, height from seafloor, slope etc. of the entire volcanic edifice are derived from the DEM grids and inserted into a database. The statistical analysis of this data combined with the history of flank failure will shed light on the influence the morphology of a volcanic island has on its instability. This will lead to a better understanding of the processes involved in the movement of instable volcanic flanks.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 5
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    Site selection for creepmeter fault monitoring in a complex volcano- tectonic framework: the Mt. Etna eastern flank as an example (2022)
    Details
    Publication Date: 2022-11-14
    Description: Mt. Etna is one of the most active volcanoes representing an exceptional natural laboratory for in-depth studies on volcano-tectonic processes. The volcano is well monitored by the INGV-OE seismic and geodetic network onshore given the high population density along its slopes, which have been affected not only by volcanic eruptions but also by damaging earthquakes. Seismicity is higher in the eastern slope which is also affected by slow gravitational sliding toward the sea with an active deformation also offshore. Flank instability is accommodated by fault systems characterized by seismic and aseismic segments with normal and strike-slip kinematics, and bounded to the N by the Pernicana Fault and to the S by the Tremestieri-Trecastagni-Aci Trezza Faults. The Trecastagni Fault is monitored by two extensometers held by INGV-OE, while offshore monitoring has been recently improved with five GEOMAR transponders along the Aci Trezza Fault offshore extension. Dyke intrusions on Etna can cause stress variations along faults triggering earthquakes and fank instability; moreover, fault creep events can follow or precede earthquakes. This pattern of interacting phenomena demonstrates how changes in the stress regime trigger seismic and aseismic transients on different faults and also causes eruptions probably related to significant extensional regime in the crust. Thus, it is important to improve the actual monitoring system with creepmeters providing time series of displacement across active faults with continuous and high-resolution measurements (1 µm). In this work we provide the first results of the geological and geophysical investigations in the Etna eastern flank and we present the methodology to characterize best suited sites, currently in progress, for future installation.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 6
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    Decline in Slope Stability as a Consequence of Gassy Soil in Submarine Slopes on the Balearic Promontory (2022)
    ASME
    Details
    Publication Date: 2022-11-22
    Description: Submarine landslides can entail a substantial hazard for offshore infrastructure as they are capable of triggering tsunamis and may develop into highly mobile turbidity currents capable of breaking seabed cables. Despite considerable research activity, the trigger mechanisms for such landslide events cannot be clearly defined. Recently, marine gas occurrence has been investigated as a possible trigger mechanism. The behaviour of a fine-grained gassy soil is influenced by a variety of micromechanical processes; amongst destructuring due to fracture formation or gas bubble expansion, and bubble flooding with subsequent cavity collapse. Capturing and modeling these processes in order to assess the destructive potential of enclosed gas bubbles in submarine slopes is to date a considerable scientific challenge. With the help of a large number of Finite Element Limit Analyses (FELA), which are based on laboratory tests on a gravity core from the western Mediterranean Sea, submarine slope stability in the respective region was evaluated. Based on these analyses, gassy soil can be defined as a preconditioning factor but not as a capable trigger mechanism for submarine landsliding.
    Type: Book chapter , NonPeerReviewed , info:eu-repo/semantics/bookPart
    Format: text
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  • 7
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    The Submarine Boundaries of Mount Etna’s Unstable Southeastern Flank (2022)
    Frontiers Media S.A.
    Details
    Publication Date: 2022-03-07
    Description: Coastal and ocean island volcanoes are renowned for having unstable flanks. This can lead to flank deformation on a variety of temporal and spatial scales ranging from slow creep to catastrophic sector collapse. A large section of these unstable flanks is often below sea level, where information on the volcano-tectonic structure and ground deformation is limited. Consequently, kinematic models that attempt to explain measured ground deformation onshore associated with flank instability are poorly constrained in the offshore area. Here, we attempt to determine the locations and the morpho-tectonic structures of the boundaries of the submerged unstable southeastern flank of Mount Etna (Italy). The integration of new marine data (bathymetry, microbathymetry, offshore seismicity, reflection seismic lines) and published marine data (bathymetry, seafloor geodesy, reflection seismic lines) allows identifying the lineament north of Catania Canyon as the southern lateral boundary with a high level of confidence. The northern and the distal (seaward) boundaries are less clear because no microbathymetric or seafloor geodetic data are available. Hypotheses for their locations are presented. Geophysical imaging suggests that the offshore Timpe Fault System is a shallow second-order structure that likely results from extensional deformation within the moving flank. Evidence for active uplift and compression upslope of the amphitheater-shaped depression from seismic data along with subsidence of the onshore Giarre Wedge block observed in ground deformation data leads us to propose that this block is a rotational slump, which moves on top of the large-scale instability. The new shoreline-crossing structural assessment may now inform and improve kinematic models.
    Description: Published
    Description: 810790
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: seafloor ; fault ; flank dynamics ; hydroacoustic ; geodesy ; seismic profiles ; 04.07. Tectonophysics ; 04.08. Volcanology ; 04.06. Seismology ; 04.02. Exploration geophysics ; 05.02. Data dissemination
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Monitoring and Mapping Active Deformation offshore Etna, Cruise No. AL532 (2022)
    Details
    Publication Date: 2022-02-02
    Description: The vessel left the port of Catania with a delay of seven days owing to bad weather conditions during the transit to Catania. The four-days long cruise with five scientists took place with excellent weather conditions without exception. The main purpose of the cruise was to collect high-resolution seafloor bathymetric data with an Autonomous Underwater Vehicle (AUV) and a ship-based multibeam echosounder. Deployment and recovery of the AUV Abyss with the Launch-and-recovery-system (LARS) was a premiere onboard RV ALKOR. Abyss did four dives, out of which two provided important data. In addition, about 250 km of ship-based echosounder tracks were sailed and three Conductivity-Temperature-Depth (CTD) profiles were taken.
    Description: GEOMAR Helmholtz Centre for Ocean Research Kiel
    Description: Published
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Keywords: seafloor ; fault ; deformation ; hydroacoustic ; 04.03. Geodesy ; 04.08. Volcanology ; 04.07. Tectonophysics ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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