On characteristics and flow dynamics of large rapid mass movements in glacial environments

• Main Author: Schneider, Demian
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2011
• Subjects: Institute of Geography; UZH Dissertations; 910 Geography & travel; Gletscher; Massenbewegung; Geomorphologie; Ice; permafrost
• Online Access: https://www.zora.uzh.ch/id/eprint/59789/; https://www.zora.uzh.ch/id/eprint/59789/1/2011_SchneiderD_2011_Diss_Schneider_Demian.pdf; https://www.zora.uzh.ch/id/eprint/59789/4/Dissertation_Schneider.pdf; https://doi.org/10.5167/uzh-59789

Current developments of the climate involve dramatic changes in the high-mountain cryosphere, such as glacial retreat, permafrost degradation, development of new glacial lakes, release of huge masses of friable and often steep debris, and altered precipitation patterns. Consequences are increased mass turnover rates, characterized by higher frequencies and magnitudes of rock falls, debris flows and slow slope movements, but also by large (V > 106 m3) and rapid mass movements such as landslides, rock-, debris- or ice-avalanches and debris flows. Large rapid mass movements in or from glacial and periglacial high mountain environments can be attributed by extraordinary mobility, flow transformations or chain reactions implying high hazard potentials if they are reaching populated areas such as demonstrated by a number of disastrous events during the last decades. The present study concentrates on the propagation and deposition of large rapid mass movements in glacial environments. This includes aspects from general landslide long-runout mechanisms, several case studies in volcanic and non-volcanic glacial environments, numerical runout modeling, seismic data analysis, physical flow experiments in the laboratory and an empirical analysis of specific flow characteristics of large rapid mass movements in glacial environments. Simple empirical runout modeling of mass movements was applied for preliminary regional hazard assessments. For specific retrospective local case studies, physically-based dynamic numerical simulations were performed. Besides required geometric similarities between the modeled and real event, the rheologic model input parameters could be better constrained by fitting dynamic model output parameters to seismic data. As a result, insights into flow dynamics of rock-ice avalanches can be improved, such as by more accurate velocity estimations that is of interest for hazard mitigation measures. Laboratory experiments in large vertically rotating drum flumes were used to quantify the influence of ...