ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics  (3)
  • Nature Publishing Group  (1)
  • Nova Science Publishers, Inc., Hauppauge, NY  (1)
  • elsevier  (1)
Collection
Keywords
Publisher
Years
  • 1
    facet.materialart.
    Unknown
    Controls of conduit geometry and wallrock elasticity on lava dome eruptions (2007)
    elsevier
    Details
    Publication Date: 2017-04-04
    Description: Many lava dome building eruptions show periodic to complex non-periodic pulsatory activity. Typical time-scales associated with this activity range from hours to decades. Previous studies modelled the ascent of magma using a set of transient 1-D transport equations, accounting for degassing induced crystallization kinetics, gas exsolution and viscosity increase due to crystal growth. These models assumed flow in a cylindrical conduit with a fixed cross-section area. Since several observations suggest that extrusions are mainly fed by dykes, with cylindrical geometries developing only at shallow levels, here we generalised the model to the flow geometry represented by an elliptical dyke with major and minor semi-axes changing with depth. Quasi-static elastic deformation of the dyke is accounted by an analytical solution that couples cross-section area with the magmatic overpressure. The effects of the main dyke geometrical parameters and boundary conditions on the eruption dynamics were investigated. The presence of a deformable dyke can lead to a more complex periodic behaviour with a wider range of time-scales and cyclicity patterns with respect to a uniform cylindrical conduit. There is a regime where the period of pulsations is controlled by the elasticity of the dyke and a regime where the period is controlled by the volume of the magma chamber. Intermediate regimes are possible. Periodic variations in discharge rate are also possible for both fixed pressure in dyke source region and fixed influx rate into the dyke. Our study emphasizes the strong nonlinearities and complex behaviours of lava dome eruptions. From a forecasting and hazard perspective, intrinsic uncertainties in governing parameters may make volcanic systems in some circumstances unpredictable. On the other hand, lava dome systems may also develop episodic and systematic behaviours so that behaviour becomes predictable for a while.
    Description: Published
    Description: 137–151
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: lava dome ; extrusive eruption ; dyke ; wallrock elasticity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    Solidification behaviour of natural silicate melts and volcanological implications (2008)
    Nova Science Publishers, Inc., Hauppauge, NY
    Details
    Publication Date: 2017-04-04
    Description: The thermodynamic and physical properties of magmas have been extensively investigated as a function of T, P, fO2 and composition allowing the development of accurate phase stability, viscosity, and diffusion models. However, how the silicate melt properties are influenced by kinetic effects is still an open question. The most important transformation of a magma is its solidification due to cooling, i.e. the transition from a silicate melt to a rock. Solidified magmas may be crystalline, vitreous, or a mixture of glass and crystals. If the cooling rate is larger enough to prevent crystallization, a magma can encompass the supercooling region without crystallisation. The smallest cooling rate that suppresses or strongly limited the nucleation of crystals is the critical cooling rate Rc. Melts with low Rc persist in a metastable liquid state and have a good glass forming ability (GFA). GFA and Rc of melts can be quantitatively estimated using (1) the reduced glass transition parameter Trg = Tg/Tm (Tg, temperature of glass transition; Tm, temperature of melting), and (2) the viscosity fragility concept. As stated by the theory, strong liquids with high Trg values have good GFA and low Rc, whereas fragile liquids with low Trg have a poor GFA and high Rc. Using available experimental data and theoretical models, we analyze the kinetic effects in dry magmas of different composition. The obtained results are relevant for the formation of lava flows and domes. In sub-alkaline magmas, Trg linearly increases and Rc decreases as the Si and Al content increases. Rc of basalts range between 101 and 103 K/s. In dacitic and rhyolitic melts, Rc is between 10-3 and 10-5 K/s. Alkaline melts have Trg values lower than those of sub-alkaline compositions. Results are consistent with the available experimental data. The sluggish kinetics of nucleation determined by using the relation Rc vs Trg is also in agreement with the experimental and theoretical data for synthetic silicate melts. The outlined solidification behaviour of magmatic melts has a profound influence on the viscosity paths of magmas. Depending on the Trg and Rc values, less evolved magmas may have a viscosity larger than that of more evolved magmas due to the rapid crystallization induced by the cooling during their flowing on the Earth. The glassy portion of poorly evolved magmas is indicative of rapid cooling, whereas the glassy fraction of evolved magmas is not unequivocally indicative of rapid cooling being their typical Rc values low. Basaltic lavas may flow on the Earth surface for long times only if they have a temperature close to Tm, whereas more evolved lavas can flow for longer periods with temperatures well below Tm. Fully glassy lavas like obsidians have invariably rhyolitic or trachytic compositions.
    Description: Submitted
    Description: in press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: open
    Keywords: crystallization ; lava flows ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 3
    facet.materialart.
    Unknown
    Dynamic feeder dyke systems in basaltic volcanoes: the exceptional example o fthe 1809 Etna eruption (Italy) (2015)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.
    Description: Published
    Description: 1-11
    Description: 2T. Tettonica attiva
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: N/A or not JCR
    Description: open
    Keywords: feeder dyke ; basaltic volcanoes ; flank eruptions ; Etna ; volcanic hazards ; sill ; volcanic rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...