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  • Elsevier Science Limited  (5)
  • Elsevier Science  (1)
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  • 1
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    Precise microsampling of poorly laminated speleothems for U-series dating (2012)
    Elsevier Science Limited
    Details
    Publication Date: 2021-06-16
    Description: One of the principal reasons why speleothems are recognised as important palaeoclimate archives is their suitability for accurate and precise uranium-series (U-series) age determination. Sampling speleothem sections for U-series dating is straightforward in most cases because visible growth layers are preserved. However, this is not always the case, and here we describe a sampling strategy whereby growth layers are resolved from trace-element images produced by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We apply this method to a section of an Italian subaqueous speleothem (CD3) that lacks persistent visible growth layering. Trace-element imaging revealed growth layers that are strongly non-planar in their geometry owing to the speleothem's pronounced euhedral crystal terminations. The most prominent trace-element layers were first digitized as x, y vector contours. We then interpolated these in the growth-axis direction to generate a series of contour lines at ∼250-μm increments. The coordinates of these contours were used to guide the sampling via a computerised micromilling lathe. This produced a total of 22 samples for U-series dating by multi-collector ICP-MS. The dating results returned ages in correct stratigraphic order within error. Close inspection of the U-series data and the derived depth–age model suggests that the main source of model-age uncertainty is unrelated to the contour sampling but instead more associated with how closely spaced the model ages are in time, i.e. the model age density. Comparisons between stable oxygen and carbon isotope profiles derived from aliquots of the dating samples and two other stable isotope profiles from CD3 spanning the same time period compare very favourably. Taken together, this suggests that our trace-element contouring method provides a reliable means for extracting samples for dating (and other geochemical analyses), and can be applied to similar speleothems lacking visible growth layering.
    Description: Published
    Description: 38-47
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: Speleothems ; U–Th dating ; Growth layers ; LA-ICP-MS ; Trace elements ; Microsampling ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Spatial relationship between earthquakes and volcanic vents in the central-northern Main Ethiopian Rift (2015)
    Elsevier Science Limited
    Details
    Publication Date: 2021-06-25
    Description: During the breakup of continents extension is commonly accommodated by connected networks of fluid filled fractures (dykes) and by faults. Despite the importance of these two extension mechanisms their spatial relationship in three dimensions is poorly understood primarily because it is difficult to quantify the subsur- face distribution of faulting and intrusion. In order to address this problem, we conduct a quantitative anal- ysis of the spatial distribution and clustering of earthquakes and volcanic vents in the Main Ethiopian Rift in East Africa in order to understand how extension by faulting and intrusion is distributed throughout the vol- canic rift. We use fractal analysis of earthquake epicentres in order to infer the 2D characteristics of the sub- surface fault network, and directly test our model results against the 3D distribution of earthquake hypocentres. Our results show that fractal analysis of these features is a reliable means to characterise the 3D properties of the fault network. In addition, the strong similarity between the properties of the fault net- work derived from earthquakes and properties of the magma-filled fracture network derived from fractal analysis of volcanic vents strongly suggests that these are genetically linked. We then explore their spatial link using computation of earthquake and vent density, which shows that the zone of seismicity is generally around 20–30-km-wide, while the zone of vents is narrower and centred within the zone of seismicity. This spatial relationship suggests that the faults, which form rift axial grabens, are induced above a narrower and central zone of diking. We also demonstrate significant along-rift variation in degree of magmatism and faulting with regions of increased degree of diking inferred from a higher cone density characterised by reduced degree of faulting.
    Description: Published
    Description: 123-133
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Volcanic vent Earthquake Spatial distribution Self-similar clustering Ethiopian Rift ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    A continuous stable isotope record from the penultimate glacial maximum to the Last Interglacial (159–121 ka) from Tana Che Urla Cave (Apuan Alps, central Italy) (2015)
    Elsevier Science Limited
    Details
    Publication Date: 2021-06-16
    Description: Relatively few radiometrically dated records are available for the central Mediterranean spanning the marine oxygen isotope stage 6–5 (MIS 6–5) transition and the first part of the Last Interglacial. Two flowstone cores from Tana che Urla Cave (TCU, central Italy), constrained by 19 U/Th ages, preserve an interval of continuous speleothem deposition between ca. 159 and 121 ka. A multiproxy record (δ18O, δ13C, growth rate and petrographic changes) obtained fromthis flowstone preserves significant regional-scale hydrological changes through the glacial/interglacial transition and multi-centennial variability (interpreted as alternations between wetter and drier periods) within both glacial and interglacial stages. The glacial stage shows a wetter period between ca. 154 and 152 ka, while the early to middle Last Interglacial period shows several drying events at ca. 129, 126 and 122 ka, which can be placed in the wider context of climatic instability emerging from North Atlantic marine andNWEuropean terrestrial records. The TCU record also provides important insights into the evolution of local environmental conditions (i.e. soil development) in response to regional and global-scale climate events.
    Description: Published
    Description: 450-461
    Description: 4A. Clima e Oceani
    Description: JCR Journal
    Description: restricted
    Keywords: Speleothem Stable isotopes Central Italy Penultimate deglaciation Last Interglacial ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    A rapid method to assess fire-related debris flow hazard in the Mediterranean region: An example from Sicily (southern Italy) (2012)
    Elsevier Science
    Details
    Publication Date: 2017-04-04
    Description: Increased atmospheric temperatures during the high-pressure which characterise the Mediterranean climate in the dry summer time, coupled with an increase in the intensity of storms in the following wet season over recent years, increase the risk of summer fires as well as debris flows and floods in the autumn and/or in the following years. In addition, the diffuse urbanization of Italy requires a rapid and reliable tool be available in order to obtain preliminary information, at the end of the summer season, that identifies newly fired areas that present a significant hazard to human populations. In such burned zones, soil instability may be more severe favouring debris flows which may impact on populated zones. Thus, in this paper we discuss a rapid methodology to: (i) identify burned areas using band ratio's using multitemporal LANDSAT ETM images; (ii) evaluate the potential of the burned areas as the source of debris flows based on morphometric parameters (slope and hill slope curvature); (iii) evaluate the structures, such as houses and roads, exposed to potential damage by debris flows. Hazardous areas were evaluated using a stochastical model coupled with an empirical relationship which accounts for the mobility of the debris flows. The methodology provides a classification of the most “dangerous” burned areas and the potentially maximum inundated downslope areas. This has been applied to Sicily for the period autumn 2001–autumn 2002. The total burned area was 76.37 km2. According to the classification proposed 6.4% of the burned areas were consider of very high to high hazard potential, 54.4% of medium hazard and 43.2% of low hazard potential.
    Description: Published
    Description: 217-231
    Description: 1.10. TTC - Telerilevamento
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: restricted
    Keywords: Fires ; Debris flows ; GIS ; Hazard ; Southern Italy ; Sicily ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Multiview 3D reconstruction in geosciences (2012)
    Elsevier Science Limited
    Details
    Publication Date: 2017-04-04
    Description: Multiview three-dimensional (3D) reconstruction is a technology that allows the creation of 3D models of a given scenario from a series of overlapping pictures taken using consumer-grade digital cameras. This type of 3D reconstruction is facilitated by freely available software, which does not require expert-level skills. This technology provides a 3D working environment, which integrates sample/field data visualization and measurement tools. In this study, we test the potential of this method for 3D reconstruction of decimeter-scale objects of geological interest. We generated 3D models of three different outcrops exposed in a marble quarry and two solids: a volcanic bomb and a stalagmite. Comparison of the models obtained in this study using the presented method with those obtained using a precise laser scanner shows that multiview 3D reconstruction yields models that present a root mean square error/average linear dimensions between 0.11 and 0.68%. Thus this technology turns out to be an extremely promising tool, which can be fruitfully applied in geosciences.
    Description: Published
    Description: 168–176
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: open
    Keywords: Multiview ; 3D reconstruction ; Laser scanner ; Outcrop ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Morphometric analysis of lava flow units: Case study over LIDAR-derived topography at Mount Etna, Italy (2012)
    Elsevier Science Limited
    Details
    Publication Date: 2017-04-04
    Description: High resolution, LIDAR-derived digital elevation models of volcanic areas can significantly improve knowledge of lava flow morphology and emplacement mechanisms. Here we focus on single flow units, presenting a new semi-automatic procedure which provides a quantitative analysis of their shape. The method relies on the automatic processing of the elevation profiles obtained on transects orthogonal to the flow unit axis. The initial phase of the Mount Etna flank eruption from September 2004 is taken as test case, and the procedure is applied on an active lava flow, which was emplaced on the eastern flank of the volcano. The main topographic dataset used is a 2-m-resolution digital elevation model obtained from a LIDAR survey. Starting from the axis of a lava flow unit, our method yields morphometric data on the flow unit at a 2 m spacing, calculating parameters including flow width, channel width, the heights of the levees, inward and outward slope of levees, and estimating pre-emplacement slope along the axis. The procedure is embedded in a customized GIS, which allows easy processing, handling and displaying of data. The procedure has also been applied to another flow unit emplaced during the October–November 1999 overflow from the Bocca Nuova crater. Results show that the channel width seems to accommodate first‐order trends of the pre-emplacement slope along the flow unit axis, while it is little affected by high frequency changes in slope; in contrast, flow unit width and flow unit thickness are apparently influenced by small‐scale changes in slope. The different emplacement conditions of the two flow units are reflected by the overall contrasting morphologies, as shown by the different average thickness and by the different ratios between (i) flow width vs. channel width and (ii) flow unit section area vs. channel width. The new method provides an enhanced, systematic and thorough morphometric description of flow units, which may improve the understanding of the emplacement mechanisms of lava flows on Earth and other planets.
    Description: Published
    Description: 11-22
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: LIDAR ; Lava flow unit ; Lava flow morphology ; High resolution DEM ; Etna ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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