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  • 1
    Publication Date: 2017-04-04
    Description: Geothermobarometry on rocks from the Joshua Flat – Beer Creek Pluton and its aureole was combined with fl uid investigations and numerical modelling. The pluton is composed of distinct bodies of diorites, monzonites and granodiorites. The granodiorite intruded the still partially molten monzonite. This led to reheating of the pluton and its aureole. Hornblende thermobaro metry gives temperatures of ca. 700 °C and pressures of about 2 kbar. In the contact aureole three metamorphic zones were distinguished with decreasing distance from the pluton: the andalusite-cordierite, sillimanite, and cordierite-K-feldspar zones, respectively. Leucocratic veins together with reaction fabrics between biotite and K-feldspar document dehydration melting due to biotite breakdown in the innermost aureole. This is supported by Na-in-cordierite thermometry and infra-red spectroscopy measurements at cordierite from metapelites. The latter showed relatively low contents of channel volatiles indicating that fl uids did not play a major role during the prograde contact metamorphic evolution of the pluton’s thermal aureole and that heat transport in the aureole was conductive. Numerical modelling of the Tt path of the pluton/wall rock system resulted in temperatures, which are close to those determined by geothermometry when assuming reheating of the system by a second intrusion. Moreover, modelling suggests a conductive nature of heat fl ow around the pluton.
    Description: Published
    Description: 13-40
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: N/A or not JCR
    Description: reserved
    Keywords: Emplacement conditions ; Hornblende/cordierite geothermobarometry ; Fluids in cordierite ; Numerical modelling ; Conductive heat fl ow ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2020-05-29
    Description: In January 2002 Mount Nyiragongo erupted foiditic lavas that covered the Southern volcano flank devastating vast urban areas. Lava flows originated from vents at different heights on the eruptive fissure displayed different velocities, from tens of km/h at the highest vents to slow-advance (0.1–1 km/h) in Goma town several km away from the volcano. To understand the different behavior of lava flows and their threat to the local population, we undertook a multidisciplinary study involving textural and rheological measurements and numerical simulations of heat transfer during magma ascent. We demonstrate that pre-eruptive cooling and syn-eruptive undercooling of magma determined the different rheological behavior of lava flows erupted from vents at diverse heights. Venting at lower altitudes is expected to produce viscous, slowly advancing lavas, although development of fluid, faster flows should be included among possible future eruptive scenarios.
    Description: Published
    Description: L06301
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Nyiragongo volcano ; textural and rheological measurements ; numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2019-11-04
    Description: Volcanic eruptions are unsteady multiphase phenomena, which encompass many inter-related processes across the whole range of scales from molecular and microscopic to macroscopic, synoptic and global. We provide an overview of recent advances in numerical modelling of volcanic effects, from conduit and eruption column processes to those on the Earth s climate. Conduit flow models examine ascent dynamics and multiphase processes like fragmentation, chemical reactions and mass transfer below the Earth surface. Other models simulate atmospheric dispersal of the erupted gas-particle mixture, focusing on rapid processes occurring in the jet, the lower convective regions, and pyroclastic density currents. The ascending eruption column and intrusive gravity current generated by it, as well as sedimentation and ash dispersal from those flows in the immediate environment of the volcano are examined with modular and generic models. These apply simplifications to the equations describing the system depending on the specific focus of scrutiny. The atmospheric dispersion of volcanic clouds is simulated by ash tracking models. These are inadequate for the first hours of spreading in many cases but focus on long-range prediction of ash location to prevent hazardous aircraft - ash encounters. The climate impact is investigated with global models. All processes and effects of explosive eruptions cannot be simulated by a single model, due to the complexity and hugely contrasting spatial and temporal scales involved. There is now the opportunity to establish a closer integration between different models and to develop the first comprehensive description of explosive eruptions and of their effects on the ground, in the atmosphere, and on the global climate.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: numerical modeling ; explosive volcanic eruptions ; conduit flow ; multiphase flow simulation ; stratospheric sulfate aerosol ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 2094932 bytes
    Format: application/pdf
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