نتایج جستجو برای: magma flow
تعداد نتایج: 488709 فیلتر نتایج به سال:
exact solution for steady two-dimensional flow of an incompressible magma is obtained. themagmatic flow is studied by considering the magma as a second grade fluid. the governing partialdifferential equations are transformed to ordinary differential equations by symmetry transformations. resultsare discussed through graphs to understand the rheology of the flowing magma
Volatiles dissolved in silicic magma at depth exsolve as the magma nears the surface and cause an increase in viscosity of the magma. A model of a volcanic conduit within an elastic medium and a viscosity dependent on the volatile content of the magma produces oscillatory magma flow for a critical range of steady input flow rates. Oscillatory flow is recognized as a fundamental mode of behavior...
Felsic magma commonly pools within shallow mushroom-shaped magmatic intrusions, so-called laccoliths or cryptodomes, which can cause both explosive eruptions and collapse of the volcanic edifice. Deformation during laccolith emplacement is primarily considered to occur in the host rock. However, shallowly emplaced laccoliths (cryptodomes) show extensive internal deformation. While deformation o...
Dome growth at the Soufriere Hills volcano (1996 to 1998) was frequently accompanied by repetitive cycles of earthquakes, ground deformation, degassing, and explosive eruptions. The cycles reflected unsteady conduit flow of volatile-charged magma resulting from gas exsolution, rheological stiffening, and pressurization. The cycles, over hours to days, initiated when degassed stiff magma retarde...
Radiographic imaging of magma dynamics in a volcanic conduit provides detailed information about ascent and descent of magma, the magma flow rate, the conduit diameter and inflation and deflation of magma due to volatile expansion and release. Here we report the first radiographic observation of the ascent and descent of magma along a conduit utilizing atmospheric (cosmic ray) muons (muography)...
[1] Lava dome eruptions are commonly characterized by large fluctuations in discharge rate with cyclic behaviour on time-scales ranging from hours to decades. Examples include Bezymianny volcano (Russia), Merapi (Java), Santiaguito (Guatemala), Mt St Helens (USA), Mt Unzen (Japan), and Soufrière Hills volcano (Montserrat). Previous models have assumed simple cylindrical conduits for magma trans...
[1] We explore physical mechanisms controlling formation of a confining conduit plug using 1D, steady-state numerical models of magma ascent. Model results for the welldocumented 1997 Vulcanian explosions at Soufrière Hills volcano were compared against subsurface conditions constrained by geophysical and petrologic analysis. We suggest that, if magma is permeable and overpressured and rock sur...
Porous flow of buoyant liquid through partially molten rock is regarded as the initial transport process leading to magma segregation in the mantle. Recent work has identified the importance of matrix deformation and compaction in this process. We present finite-difference calculations based on a generalized form of Darcy's law that includes matrix deformation, in two-dimensional Cartesian and ...
Magma viscosity is strongly temperature-dependent. When hot magma flows in a conduit, heat is lost through the walls and the temperature decreases along the flow causing a viscosity increase. For particular values of the controlling parameters the steady-flow regime in a conduit shows two stable solutions belonging either to the slow or to the fast branch. As a consequence, this system may show...
The Hapaimamo flow contains xenoliths of gabbronorites, troctolites, dunites, websterites and periodotites. Composition of cumulate olivines ranges from Fo78-86, clinopyroxenes ranges from En47-53Wo37-40Fs8-12, and orthopyroxenes ranges from En71-83Wo2-5Fs13-25. Most xenoliths display an intergranular, subpoikilitic or poikilitic texture. Petrologic and compositional information point towards a...
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