9 September 2021
Paimio: a very unusual landslide in Finland
Last week a very unusual and interesting landslide occurred close to the town of Paimio in Finland. The image below, published on ts.fi, provides a wonderful overview of the landslide:-
Once again I don’t think I’ve seen one quite like this before. The source area appears to be an aggregate storage area from a nearby quarry. The aggregate pile has has clearly failed – there is a scar and some tension cracks visible. The material in the fields appears to be clay, common in formerly glaciated areas. The failure of the aggregate pile has propagated through the clay substrate over a distance of perhaps 100 metres, forming a set of compressive ridges. This is unusual.
It is interesting to ponder what might have happened here. My working hypothesis is that this might be a bearing capacity failure in the clay below the aggregate pile – essentially the clay did not have the shear strength to withstand the stresses imposed by the heap. Its failure caused the pile to collapse.
The nearest comparative event I can remember of the Hatfield Colliery failure close to my now home in Sheffield, in England. In this case colliery spoil was piled on gravels that subsequently failed. However, in the case of the landslide at Paimio the failure has propagated a relatively longer distance from the source, presumable reflecting the properties of the clay.
Fortunately no-one was killed or injured in the landslide at Paimio, and only one building was damaged.
The location of the landslide is, I believe, 60.434, 22.610. There is a Google Earth image of the site from 2018:-
Interestingly this image does not show the large pile of aggregate that was involved in the failure, so this might be a comparatively recent addition.
Many thanks to loyal reader Tomi for highlighting this one to me.