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| Titel |
Coupling limit equilibrium analyses and real-time monitoring to refine a landslide surveillance system in Calabria (southern Italy) |
| VerfasserIn |
G. G. R. Iovine, P. Lollino, S. L. Gariano, O. G. Terranova |
| 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 ; 10, no. 11 ; Nr. 10, no. 11 (2010-11-22), S.2341-2354 |
| Datensatznummer |
250008502
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| Publikation (Nr.) |
 copernicus.org/nhess-10-2341-2010.pdf |
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| Zusammenfassung |
On 28 January 2009, a large debris slide was triggered by prolonged
rainfalls at the southern suburbs of San Benedetto Ullano (Northern
Calabria). The slope movement affected fractured and weathered migmatitic
gneiss and biotitic schist, and included a pre-existing landslide. A
detailed geomorphologic field survey, carried out during the whole phase of
mobilization, allowed to recognize the evolution of the phenomenon. A set of
datum points was located along the borders of the landslide and frequent
hand-made measurements of surface displacements were performed. Since 11
February, a basic real-time monitoring system of meteoric parameters and of
surface displacements, measured by means of high-precision extensometers,
was also implemented.
Based on the data gained through the monitoring system, and on field
surveying, a basic support system for emergency management could be
defined since the first phases of activation of the phenomenon. The
evolution of the landslide was monitored during the following
months: as a consequence, evidence of retrogressive distribution
could be recognized, with initial activation in the middle sector of
the slope, where new temporary springs were observed. During early
May, the activity reduced to displacements of a few millimetres per
month and the geo-hydrological crisis seemed to be concluded.
Afterwards, the geological scheme of the slope was refined based on
the data collected through a set of explorative boreholes, equipped
with inclinometers and piezometers: according to the stratigraphic
and inclinometric data, the depth of the mobilized body resulted in
varying between 15 and 35 m along a longitudinal section. A
parametric limit equilibrium analysis was carried out to explore the
stability conditions of the slope affected by the landslide as well
as to quantify the role of the water table in destabilizing the
slope. The interpretation of the process based on field observations
was confirmed by the limit equilibrium analysis: the first
activation of the landslide was, in fact, to be expected in the
middle portion of the slope, provided that the groundwater levels
approximate the ground surface in the same sector.
On 1 February 2010, another remarkable phase of landslide
mobilization began, following a new period of exceptional and
prolonged rainfalls. On 11 February, an abrupt stage of slope
acceleration was observed, after further extraordinary rainfalls.
The slope movement essentially replicated the phases of mobilization
observed on 28 January 2009, thus confirming the results of the
limit equilibrium analysis. Based on the outcomes of the parametric
analysis, the support system for emergency management could then be
tentatively refined on a more physical basis. |
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