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| Titel |
High-resolution geophysical and hydrological observations of surface and subsurface dynamics at the slow-moving Super-Sauze landslide (South French Alps) |
| VerfasserIn |
Sabrina Rothmund, Marco Walter, Jean-Philippe Malet, Manfred Joswig |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050845
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| Zusammenfassung |
| The Super-Sauze landslide (Southern French Alps) is completely water-saturated in spring
after the snowmelt, and is drying out in the uppermost layer (2 m) in summer. The decrease
of water saturation in the topsoil, the drainage of the groundwater table and the
displacement rate (of nearly 0.01 to 0.04 m.day-1) causes fissures development at the
surface. These fissures, which are characterized by different specific orientation,
distribution, opening and clogging, are very often located in the same parts of the
landslide and their spatial pattern reflects the interactions between the rheology of the
sliding material and the bedrock topography. These fissures have opposite effects on
the dynamics of the landslide, either destabilizing by conducting rain water to the
groundwater table or stabilizing by dissipating pore water pressures in extension
zones.
The fissures can be detected and mapped in very high-resolution UAV-based aerial images. In
addition, small impulsive signals in the subsurface caused by stress relief or fissure
development can be detected by nanoseismic monitoring.
To better understand the mechanism underlying the landslide dynamics, the relationship of
small fracture processes with slope movement, fissure developments and pore water pressure
build-up has been investigated. For this purpose a multi-technique and high-resolution
monitoring campaign was performed for eight weeks after the snowmelt from late May to late
July 2010 over an area of about 10.000 m2. The surface slope dynamics has been observed by
UAV-based aerial images, ground-based optical images, terrestrial laser scanning (TLS),
thermal infra-red images as well as permanent and non permanent DGPS. The subsurface
dynamics has been monitored by nanoseismic monitoring for fracture processes and
electrical resistivity tomography (ERT) for soil moisture analysis. Shallow piezometers
provided information of the pore water pressure, and meteorological data were
available.
In the middle of the monitoring period (15thJune 2010), a heavy-rain event caused many
shallow landslides in the surrounding area. This rain event offers an interesting opportunity to
examine the short-term extreme effects of rapid rain infiltration on the dynamics of the
landslide. First results of surface deformation and water infiltration will be presented. |
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