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| Titel |
Large historical eruptions at subaerial mud volcanoes, Italy |
| VerfasserIn |
M. Manga, M. Bonini |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 12, no. 11 ; Nr. 12, no. 11 (2012-11-16), S.3377-3386 |
| Datensatznummer |
250011196
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| Publikation (Nr.) |
 copernicus.org/nhess-12-3377-2012.pdf |
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| Zusammenfassung |
| Active mud volcanoes in the northern Apennines, Italy, currently have gentle
eruptions. There are, however, historical accounts of violent eruptions and
outbursts. Evidence for large past eruptions is also recorded by large decimeter rock clasts preserved in erupted mud. We measured the
rheological properties of mud currently being erupted in order to evaluate
the conditions needed to transport such large clasts to the surface. The mud
is well-characterized by the Herschel-Bulkley model, with yield stresses
between 4 and 8 Pa. Yield stresses of this magnitude can support the weight
of particles with diameters up to several mm. At present, particles larger
than this size are not being carried to the surface. The transport of larger
clasts to the surface requires ascent speeds greater than their settling
speed in the mud. We use a model for the settling of particles and
rheological parameters from laboratory measurements to show that the
eruption of large clasts requires ascent velocities > 1 m s−1, at
least three orders of magnitude greater than during the present,
comparatively quiescent, activity. After regional earthquakes on 20 May and
29 May 2012, discharge also increased at locations where the stress changes
produced by the earthquakes would have unclamped feeder dikes below the mud
volcanoes. The magnitude of increased discharge, however, is less than that
inferred from the large clasts. Both historical accounts and erupted
deposits are consistent in recording episodic large eruptions. |
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