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| Titel |
Volcanic soils and landslides: a case study of the island of Ischia (southern Italy) and its relationship with other Campania events |
| VerfasserIn |
S. Vingiani, G. Mele, R. Mascellis, F. Terribile, A. Basile |
| 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 ; 6, no. 2 ; Nr. 6, no. 2 (2015-06-26), S.783-797 |
| Datensatznummer |
250115466
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| Publikation (Nr.) |
 copernicus.org/se-6-783-2015.pdf |
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| Zusammenfassung |
An integrated investigation was carried out on the volcanic soils involved in
the landslide phenomena that occurred in 2006 at Mt. Vezzi on the island of
Ischia (southern Italy). Chemical (soil pH, organic carbon content,
exchangeable cations and cation exchange capacity, electrical conductivity,
Na adsorption ratio and Al, Fe and Si forms), physical (particle and pore
size distribution, pore structure), hydrological (soil water retention,
saturated and unsaturated hydraulic conductivity), mineralogical and
micromorphological analyses were carried out for three soil profiles selected
in two of the main head scarps.
The studied soils showed a substantial abrupt discontinuity in all the
studied properties at the interface with a buried fine ash layer (namely, the
2C horizon), that was only marginally involved in the sliding surface of the
landslide phenomena. When compared to the overlying horizons, 2C showed
(i) fine grey ash that is almost pumice free, with the silt content
increasing by 20 %; (ii) ks values 1 order of magnitude
lower; (iii) a pore distribution concentrated into small
(15–30 μm modal class) pores characterised by a very low
percolation threshold (approximately 15–25 μm); (iv) the
presence of expandable clay minerals; and (v) increasing Na content in the
exchange complex. Most of these properties indicated that 2C was a lower
permeability horizon compared to the overlying ones. Nevertheless, it was
possible to assume this interface to be an impeding layer to vertical water
fluxes only by the identification
of a thin (6.5 mm) finely
stratified ash layer, on top of 2C,
and of the hydromorphic features (e.g. Fe / Mn concretions) within and on
top of the layer. Although Mt. Vezzi's soil environment has many properties
in common with those of other Campania debris-mudflows (e.g. high gradient,
north-facing slope, similar forestry, and volcanic origin of the parent
material), the results of this study suggest a more complex relationship
between soil properties and landslides and emphasise the role of vertical
discontinuities as noteworthy predisposing factors. |
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