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  • Magma Ascent  (2)
  • pyroclastic density currents  (2)
  • 1
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    A novel strategy to enhance kinetic energy models by considering channelization processes of PDCs (2020)
    MISCELLANEA INGV 52, ISSN 2039-6651
    Details
    Publikationsdatum: 2020-11-09
    Beschreibung: Kinetic energy models are tools able to provide an estimate to the inundation area of pyroclastic density currents (PDCs). We present here a novel strategy that allows improving these models in order to consider the occurrence of channelization processes of pyroclastic material. In this strategy, the inundation area associated with a basal collapse process, represented by a root conoid that interacts with the topography, is complemented with the inundation zones derived from the inclusion of secondary source points located in the expected zones of pyroclast channelization (represented by branch conoids). For that, we adopt a tree branch-like structure and appropriate assumptions for setting the position and the initial characteristics of the secondary source points. Two widely used kinetic models are modified by applying this strategy: the energy cone and the box model, giving place to two open-source and freely downloadable codes (ECMapProb and BoxMapProb). We tested these branching formulations by comparing their results with those derived from the traditional formulations of these kinetic energy models, with other numerical solvers, and with the invasion area of real PDC deposits. We show the capability of the presented strategy of improving the accuracy of kinetic models without adding new, unconstrained input parameters or significantly increasing the computational cost, allowing the assessment of volcanic hazards using a probabilistic approach. The application of this strategy represents a time-effective alternative to the use of more sophisticated models for describing PDC transport and deposition.
    Beschreibung: Published
    Beschreibung: Catania
    Beschreibung: 5V. Processi eruttivi e post-eruttivi
    Schlagwort(e): pyroclastic density currents ; box model
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: Conference paper
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 2
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    The historical record of pyroclastic density currents at Stromboli and perspective for future hazard assessment (2020)
    Details
    Publikationsdatum: 2020-11-09
    Beschreibung: The formation of pyroclastic density currents (PDC) at Stromboli has been described several times. PDCs are associated with paroxysms, lava emissions and commonly confined into the Sciara del Fuoco (SdF). At least during 1906, 1930 and 1944 paroxysms PDCs were produced on the flanks of Stromboli, out of the SdF. PDCs flowed in valleys cut on the volcano flanks and reached the sea producing vast deltas. In 1930 two flows reached the Stromboli village causing victims. During the 3 July paroxysm, pyroclastic material was emplaced on steep slopes right above the village of Ginostra and small avalanches of incandescent rocks were produced. In light of recent events, PDCs were produced also inside the SdF, reached the sea and continued to flow over the water for several hundred meters. PDCs potentially represent the most dangerous manifestation of volcanic activity at Stromboli and need a proper hazard assessment.
    Beschreibung: Published
    Beschreibung: Catania
    Beschreibung: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Schlagwort(e): Stromboli ; pyroclastic density currents
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: Conference paper
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 3
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    Physical constraints for effective magma-water interaction along volcanic conduits during silicic explosive eruptions (2018)
    GSA
    Details
    Publikationsdatum: 2021-05-12
    Beschreibung: The entry of groundwater into volcanic conduits has been proposed as a major modifying agent of eruptive dynamics, influencing magma fragmentation and pyroclast dispersion. Although several external water sources and interaction mechanisms have been proposed, the nature and effects of magma-water interaction are still largely unclear, as well as its controlling factors. A common postulate for phreatomagmatic activity to occur is that pressure in a conduit crosscutting a subsurface aquifer should drop below the aquifer pressure, which depends on the properties of the aquifer and the ascending magma. In agreement with most phreatomagmatic eruptions, we show that the injection of large mass fractions of groundwater during silicic explosive eruptions (e.g., 〉5 wt%) is only physically feasible for low-eruption-rate events; while high-intensity eruptions with evidence of magma-water interaction are probably related to other interaction mechanisms (e.g., the involvement of surface water or the destabilization of aquifer-hosting rocks during collapse phases). Because conditions for access of groundwater to the conduit are preferably reached above the fragmentation level, magma-water interaction seems not to induce dramatic changes to the features of a primary ‘dry’ vesiculation, as commonly claimed. Hence, the low vesicularity indexes often attributed to phreatomagmatic eruptions are difficult to explain by the quenching effect of groundwater on not-fully developed vesicularity. Instead, these indexes may be related to the low eruption rates needed for effective magma-water interaction, generally characterized by significant lateral gradients of vesicularity in narrow conduits.
    Beschreibung: Published
    Beschreibung: 867-870
    Beschreibung: 5V. Processi eruttivi e post-eruttivi
    Beschreibung: JCR Journal
    Schlagwort(e): magma-water ; Magma Ascent ; phreatomagmatic eruptions ; 04.08. Volcanology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 4
    facet.materialart.
    Unbekannt
    Conduit stability effects on intensity and steadiness of explosive eruptions (2018)
    Nature Publishing Group
    Details
    Publikationsdatum: 2019-10-24
    Beschreibung: Conduit geometry affects magma ascent dynamics and, consequently, the style and evolution of volcanic eruptions. However, despite geological evidences support the occurrence of conduit widening during most volcanic eruptions, the factors controlling conduit enlargement are still unclear, and the effects of syn-eruptive variations of conduit geometry have not been investigated in depth yet. Based on numerical modeling and the application of appropriate stability criteria, we found out a strong relationship between magma rheology and conduit stability, with significant effects on eruptive dynamics. Indeed, in order to be stable, conduits feeding dacitic/rhyolitic eruptions need larger diameters respect to their phonolitic/trachytic counterparts, resulting in the higher eruption rates commonly observed in dacitic/rhyolitic explosive events. Thus, in addition to magma source conditions and viscosity-dependent efficiency for outgassing, we suggest that typical eruption rates for different magma types are also controlled by conduit stability. Results are consistent with a compilation of volcanological data and selected case studies. As stability conditions are not uniform along the conduit, widening is expected to vary in depth, and three axisymmetric geometries with depth-dependent radii were investigated. They are able to produce major modifications in eruptive parameters, suggesting that eruptive dynamics is influenced by syn-eruptive changes in conduit geometry.
    Beschreibung: Published
    Beschreibung: 4125
    Beschreibung: 5V. Processi eruttivi e post-eruttivi
    Beschreibung: JCR Journal
    Schlagwort(e): Volcanology ; Magma Ascent ; 04.08. Volcanology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
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