Slope instabilities on perennially frozen and glacierised rock walls: multi-scale observations, analyses and modelling

• Main Author: Fischer, L
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2009
• Subjects: Institute of Geography; UZH Dissertations; 910 Geography & travel; Monte Rosa; permafrost
• Online Access: https://www.zora.uzh.ch/id/eprint/31038/; https://www.zora.uzh.ch/id/eprint/31038/1/Fischer_Slope_Instabilities_2009.pdf; https://doi.org/10.5167/uzh-31038

Slope failures from steep bedrock slopes have occurred in mountain areas throughout time. This is a consequence of the topography, geological characteristics, intense freeze-thaw activity and oversteepened slopes from glacier erosion. However, during the past decades, an increased number of periglacial rock avalanche events have been recorded in the European Alps and other high mountain ranges which are thought to be related to permafrost degradation and glacier shrinkage, indicating the potentially serious hazard related to slope instabilities originating from high-mountain faces. The primary aim of this study is an interdisciplinary investigation of topographic, geological, cryospheric and climatic factors influencing high-mountain rock slope stability in view of the ongoing climatic change. The investigation of slope instabilities in high-mountain faces must account for the large variety of factors and processes and also consider the difficult conditions for data acquisition. The objectives of this study, where detachment zones of recent periglacial rock avalanches in the European Alps are investigated based on a multi-scale approach, can be divided in (a) the investigation and modelling of slope instabilities on periglacial high-mountain faces in order to better understand the different factors and processes leading to a slope failure, and (b) the application of different data acquisition and investigation techniques to test their suitability for steep faces in complex and difficult high-mountain terrain. The implemented approaches consist of 1) a GIS-based statistical multi-factor analysis of detachment zones over the entire Central European Alps based on a rock avalanche inventory, 2) a GIS-based multi-factor analysis and detailed remote-sensing-based time-lapse topographic investigations of the Monte Rosa east face using LiDAR and digital photogrammetry, and 3) geomechanical analysis and numerical slope stability modelling of the Tschierva rock avalanche at the Piz Morteratsch. This study has shown that ...