14 November 2019
Lokeberg: an interesting quick clay slide triggered by piling in Western Sweden
In Lokeburg in western Sweden a significant landslide occurred yesterday (13 November 2019). Anton Larsson kindly highlighted this event to the community via Twitter, posting photographs of the aftermath.
The large volume of displaced material under the now deformed and moved jetty is clear. In the trees on the left side of the image is a nicely formed rear scarp of the landslide. But note in the trees there is also clear evidence of a crane, and on the road there is a truck. News reports in Sweden link the landslide to the construction of a house at this location.
The location of the landslide is 57.903, 11.753, and there is good Google Earth imagery of the site:-
“Based on news reports, the workers were piling the area to ensure stability ahead of a rather luxurious beach house being built.”
However, subsequent reports have confirmed that it was not piling, but ground improvement through lime/cement-stabilization (which makes more sense in terms of the equipment present at the site). Thanks to Carolina for her helpful comment below that has clarified this point.
The most likely explanation for this landslide is that it is a quick clay slide. Quick clays are materials laid down in glaciomarine conditions that are “sensitive“, meaning that their strength can abruptly reduce when subjected to rapid changes in stress. The effect might be very local initially, but spreads through the deposit rapidly as the stress change propagates. This can lead to large-scale failures.
In this case a good working hypothesis would be that the piling operation generated the abrupt stress change that initiated the failure. Fortunately, the extent of the quick clay deposit was not particularly large, so the failure was contained.