WP1 – From cause to forecasting


The goal of WP1 was: (1) to review and compile the causes (disposition), trigger mechanisms, and inherent quantitative and qualitative thresholds of motion for Extremely Rapid Mass Movements; (2) to test the applicability of triggers and thresholds for inter-regional comparison with respect to environmental boundary conditions, such as climate, terrain, vegetation cover and human interference; and (3) to put together and evaluate international state-of-the-art methods and technologies for modelling and forecasting the triggering mechanisms, runout, and damage potential of the selected rapid mass movements.

A detailed review of international literature and data was conducted on the (a) causes, (b) trigger mechanisms, and (c) associated thresholds of motion for debris flows, rock avalanches, and snow avalanches, and serves as the background for summarizing the state-of-the-art in process- and prediction-based research.
The state-of-the art of methods and techniques for modelling and forecasting extremely rapid mass movements was summarized in three comprehensive reports. These summaries include an evaluation of costefficiency, applicability, compatibility, and rapidity of implementation of these methods and technologies in European mountain areas. Some of these modelling tools have also been improved as a result of this work package.
The regional variation of causes and triggers with respect to their applicability in up-/down-scaling and modelling was also reviewed. This study includes a discussion of the limits of prediction techniques. The three processes snow avalanches, debris flows, and rock avalanches exhibit extreme differences in:
• Frequency
• Process knowledge
• Databases
• Experts knowledge and experience
• Forecasting practice
• International harmonization
• Defined and accepted hazard scales


Of the three processes, the triggers of snow avalanches are best understood because their frequency and interference with living and leisure activities have resulted in the availability of a huge amount of data and information, which can be analysed to throw light on trigger mechanisms and forecasting. Moreover, the basic substrate for snow avalanches, as opposed to debris flow and rock avalanches, is annually re-supplied in the release zone and removed in the run-out zone, thus providing repeatedly very similar conditions for the process. Given these favourable conditions, the forecasting of snow avalanches is comparably very precise regarding the release time and extent of an event.
Considerable advances have also been made in understanding the dynamics and triggers of debris flows in recent years. However, forecasting of debris flows remains less precise than for snow avalanches due to the lack of relevant data, especially concerning the prerequisites causing an event, such as soil humidity and spatially precise precipitation forecasts. Yet, there is great potential for transferring forecast knowledge between the different processes, particularly snow avalanches and debris flows.
In contrast to snow avalanches and debris flows, the trigger mechanisms of rock avalanches are much more difficult to understand, which means it is nearly impossible to forecast rock avalanches unless the spatial area where they occur is already known, e.g. from past events and movements. However, hazards that may occur subsequent to rock avalanches, such as the formation of valley barriers or tsunamis, can be predicted and estimated in a more reliable manner.




  Catalogue of causes, triggers, and triggering thresholds for extremely rapid mass movements for a range of environmental boundary conditions   WP 1, D1.1 PDF, 5.8MB
  Report on the use of causes and triggers for up-/downscaling and interregional comparison   WP 1, D1.2 PDF, 3.7MB
  State-of-the-art review of methods and technologies for modelling and forecasting extremely rapid mass movements   WP 1, D1.3 PDF, 5.8MB
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