Publication Date:
2011-05-01
Description:
INTRODUCTION Landslides generally impose a considerable threat to human life, infrastructure, and the environment, especially in alpine areas. Landslides belong to the phenomena of mass movements, such as rock falls, avalanches, and debris flows. Although landslides and debris flows have much in common at first sight, they differ strongly with respect to underlying physical processes, as elaborated in Armanini and Michiue (1997) and Wang et al. (2004, 2007). Landslides are categorized as shallow or deep seated. Shallow landslides have a vertical extent up to a few meters and horizontal extent up to a few hundred square meters. Formation of shallow landslides mostly occurs in response to extreme rainfall events (Terlien, 1998; Delmonaco and Margottini, 2004) and depends on near surface structures and processes. Understanding and predicting shallow landslides is a more straight forward exercise, when compared to deep seated landslides, although it is by no means simple. Deep seated landslides have a vertical extent up to several tens of meters and spread horizontally from a hundred to a few thousand square meters. They are distinguished into fast moving and creeping landslides. Fast moving, or active, landslides, such as the "Super-Sauze" in the French Alps (Malet et al., 2003), exhibit movement rates of up to tens of meters per year. Creeping landsides move several centimeters or decimeters per year; a prominent example is Sibratsgfäll/Rindberg in Vorarberg Austria (Jaritz et al., 2008). Understanding the cause-and-effect relationships of deep seated landslides is much less straight forward than those of shallow landslides because: (i) they are controlled by multiple structures that in turn affect multiscale interactions and feedbacks between hydrologic, geohydraulic, and soil mechanical processes, and (ii) both short- and long-term triggers affect soil deformation, shear band formation, and thus movement of the creeping hillslope body. Short-term triggers are heavy rainfall events, vadose zone and groundwater flows, and pressure dynamics, but they can also include river bank or hillfoot erosion during flood events, depending on site conditions. Long-term triggers include seasonal changes of the self-load, due to seasonal soil moisture variations and snow cover, and the contribution of trees and infrastructure to the self-load...
Electronic ISSN:
1539-1663
Topics:
Geosciences
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Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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