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| Titel |
Dynamics of magma flow near the vent: Implications for dome eruptions |
| VerfasserIn |
Helène Massol, Claude Jaupart |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038715
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| Zusammenfassung |
| Magma erupting out of a volcanic vent into a flow or a dome is subjected to a marked change
of boundary conditions which strongly affects the distribution of gas pressure and stress
within the flow. A numerical code is implemented to study the role of degassing-induced
crystallization. The 2-D governing equations for a compressible viscous liquid are solved
with a fully axially symmetric Finite Element Model for different crystal contents
and vent geometrical shapes. The potential effects of gas pressure, deformation
rates and elongational stresses on the stability of endogenous dome growth are
studied for two shallow vent structures. For common eruption conditions, values
of the internal gas pressure at the vent may be as large as 2 MPa. The magnitude
of gas pressure at the vent is sensitive to the amount of crystallization and to the
shape of the shallow conduit beneath the vent. High tensile stresses of - 2 MPa
are generated at the vent, which may account for ring fracturing of the dome and
gas escape through shallow fissures. Such failure conditions may also lead to a
change of exit conditions, from lateral spreading to the vertical protrusion of a lava
spine. |
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