11 February 2015
A very nice video has been posted on Youtube, showing a stop motion video of the movement of a large landslide in Val Parghera in Switzerland. This slide is being monitored as part of the Geopraevent programme on behalf of the Canton of Grisons. The video captures movements of the landslide between May 2013 and January 2015:
There is much of interest in this film, but I’ll just point out a few things. First, when viewed at this speed it becomes clear that the behaviour of the Val Parghera landslide is very much like a fluid flow, even to the extent of seeing higher velocities in the lower, narrow part of the landslide. Second, there is a very complex coupling between the main body of the landslide and this lower portion. At times it appears that the lower part slides first, removing the support for the main body of the landslide, whilst at others it seems that the main portion moves, loading the lower part of the slope. And third, the most impressive movement event occurs at the end of March 2014 – this is a screenshot of the failure developing:
I am sure that its no coincidence that this occurred at the end of the winter – one of the notable aspects is the thawing of the snow cover as the landslide movement event proceeds. According to Geopraevent, the movement event led to the closure of a local road, and a full monitoring system is now in place. It would be fascinating to do a full analysis of the movment patterns of this landslide along the lines of the work that we did on the Tessina landslide a decade (see Petley et al. 2005).
Petley, D. N., Mantovani, F. and Bulmer, M. H. K. and Zannoni, F. (2005) The use of surface monitoring data for the interpretation of landslide movement patterns, Geomorphology., 66 (1-4). pp. 133-147.