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| Titel |
Rheological control on the dynamics of explosive activity in the 2000 summit eruption of Mt. Etna |
| VerfasserIn |
D. Giordano, M. Polacci, P. Papale, L. Caricchi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 1, no. 1 ; Nr. 1, no. 1 (2010-07-01), S.61-69 |
| Datensatznummer |
250000118
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| Publikation (Nr.) |
 copernicus.org/se-1-61-2010.pdf |
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| Zusammenfassung |
| In the period from January to June 2000 Mt. Etna exhibited an exceptional
explosive activity characterized by a succession of 64 Strombolian and
fire-fountaining episodes from the summit South-East Crater. Textural
analysis of the eruptive products reveals that the magma associated with the
Strombolian phases had a much larger crystal content (>55 vol%) with
respect to the magma discharged during the fire-fountain phases (~35
vol%). Rheological modelling shows that the crystal-rich magma falls in a
region beyond a critical crystal content where small addition of solid
particles causes an exponential increase of the effective magma viscosity.
When implemented into the modeling of steady magma ascent dynamics (as
assumed for the fire-fountain activity), a large crystal content as the one
found for products of Strombolian eruption phases results in a one order of
magnitude decrease of mass flow-rate, and in the onset of conditions where
small heterogeneities in the solid fraction carried by the magma translate
into highly unsteady eruption dynamics. We argue that crystallization on top
of the magmatic column during the intermediate phases when magma was not
discharged favoured conditions corresponding to Strombolian activity, with
fire-fountain activity resuming after removal of the highly crystalline top.
The numerical simulations also provide a consistent interpretation of the
association between fire-fountain activity and emergence of lava flows from
the crater flanks. |
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