The occurrence of Mt Barca flank eruption in the evolution of the NW periphery of Etna volcano (Italy) |
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| Authors: | S Branca P Del Carlo M D Lo Castro E De Beni J Wijbrans |
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| Institution: | (1) Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy;(2) Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, via della Faggiola 32, 56126 Pisa, Italy;(3) Faculteit Aard-en Levenswetenschappen, Vrije Universiteit, Amsterdam, The Netherlands |
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| Abstract: | Geological surveys, tephrostratigraphic study, and 40Ar/39Ar age determinations have allowed us to chronologically constrain the geological evolution of the lower NW flank of Etna
volcano and to reconstruct the eruptive style of the Mt Barca flank eruption. This peripheral sector of the Mt Etna edifice,
corresponding to the upper Simeto valley, was invaded by the Ellittico volcano lava flows between 41 and 29 ka ago when the
Mt Barca eruption occurred. The vent of this flank eruption is located at about 15 km away from the summit craters, close
to the town of Bronte. The Mt Barca eruption was characterized by a vigorous explosive activity that produced pyroclastic
deposits dispersed eastward and minor effusive activity with the emission of a 1.1-km-long lava flow. Explosive activity was
characterized by a phreatomagmatic phase followed by a magmatic one. The geological setting of this peripheral sector of the
volcano favors the interaction between the rising magma and the shallow groundwater hosted in the volcanic pile resting on
the impermeable sedimentary basement. This process produced phreatomagmatic activity in the first phase of the eruption, forming
a pyroclastic fall deposit made of high-density, poorly vesicular scoria lapilli and lithic clasts. Conversely, during the
second phase, a typical strombolian fall deposit formed. In terms of hazard assessment, the possible occurrence of this type
of highly explosive flank eruption, at lower elevation in the densely inhabited areas, increases the volcanic risk in the
Etnean region and widens the already known hazard scenario. |
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| Keywords: | Etna volcano Unconformity Tephrostratigraphy 40Ar/39Ar age determination Flank eruption Eruptive style Simeto River |
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