The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
On 23 September 2023 a very significant landslide occurred at Stenungsund in Sweden, causing extensive damage to a major road, the E6 motorway between Gothenburg and Oslo (across the border in Norway) and a number of buildings. Fortunately, no-one was killed, but three people were injured when their cars crashed on the margins of the landslide.
Loyal reader Anton Larsson was quickest off the blocks in terms of highlighting this event via Twitter – thank you – including these images of the aftermath:-
As the image shows, the landslide has caused several metres of displacement across two roads, including the motorway on the outskirts of Stenungsund, and there are several damaged buildings.
In a landslide like this, I always tell my students to take a look at the toe of the slide and at the crown area, which often provide a clue as to what might have happened. There is an article on a blog in Sweden that has done exactly this, with a set of high resolution drone images. The author, Lars Wilderäng, has tweeted this image of the crown area of the landslide:-
It is clear that there was extensive works occurring in the upper portion of what has become the landslide, which is being described as a landfill operating with permission. The most recent Google Earth imagery, from 2021 (despite what it says on the image), shows this area of activity:-
However, Planet imagery from 17 September 2023, just a few days before the landslide, indicates that the area of landfilling had become much larger:-
An initial working hypothesis would be that the mass of material deposited on what has become the headscarp of the landslide has destabilised the slope, triggering failure. The weather conditions at the time were rainy, and there has been heavy rainfall in recent days, but this has not been exceptional.
Undoubtedly a key focus now will be to understand what has happened in the headscarp area. Swedish newspapers are reporting that the events are being investigated as an environmental crime.
Meanwhile, the closure of the road is causing severe disruption, so there is pressure to reopen the motorway as soon as possible. The long term fix to a landslide like this is likely to take a considerable amount of time.
Reference and acknowledgements
Planet Team (2023). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/
Many thanks to the various loyal readers who highlighted this one to me, and in particular to those who provided links and information, such as Pascal Orrit, Nik Kelly and Anton Larsson, alongside several others. It helps greatly.