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| Titel |
Can vesicle size distributions assess eruption intensity during volcanic activity? |
| VerfasserIn |
A. LaRue, D. R. Baker, M. Polacci, P. Allard, N. Sodini |
| 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 ; 4, no. 2 ; Nr. 4, no. 2 (2013-10-18), S.373-380 |
| Datensatznummer |
250084939
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| Publikation (Nr.) |
 copernicus.org/se-4-373-2013.pdf |
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| Zusammenfassung |
| We studied three-dimensional (3-D) vesicle size distributions by X-ray
microtomography in scoria collected during the relatively quiescent Phase II
of the April–May 2010 eruption at Eyjafjallajökull volcano, Iceland. Our
goal was to compare cumulative vesicle size distributions (VSDs) measured in
these samples with those found in Stromboli volcano, Italy. Stromboli was
chosen because its VSDs are well-characterized and show a correlation with
eruption intensity: typical Strombolian activity produces VSDs with
power-law exponents near 1, whereas larger and more energetic vulcanian-type
explosions and Plinian eruptions produce VSDs with power-law exponents near
1.5. The first hypothesis to be tested was whether or not the samples
studied in this work would contain VSDs similar to normal Strombolian
products, display higher power-law exponents, or be described by exponential
functions. Before making this comparison, we tested a second hypothesis,
which was that the magma–water interactions in the Eyjafjallajökull
eruption might have a significant effect on the VSDs. We performed 1 bar
bubble-growth experiments in which the samples were inundated with water and
compared them to similar control experiments without water inundation. No
significant differences between the VSDs of the two sets of experiments were
found, and the second hypothesis is not supported by the experimental
evidence. The Phase II Eyjafjallajökull VSDs are described by power-law
exponents of ~0.8, typical of normal Strombolian eruptions,
and support the first hypothesis. The comparable VSDs and behavior of Phase
II of the Eyjafjallajökull 2010 eruption to Stromboli are interpreted to
be a reflection of similar conduit systems in both volcanoes that are being
constantly fed by the ascent of mingled/mixed magma from depth. Such
behavior implies that continued activity during Phase II of the
Eyjafjallajökull eruption could be expected and would have been
predicted, had our VSDs been measured in real time during the eruption.
However, the products studied show no peculiar feature that could herald the
renewed eruption intensity observed in the following Phase III of the
eruption. |
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