25 July 2022
New peat landslides in Shetland (including a very interesting landslide video)
The Shetland islands, off the far north coast of Scotland, are covered with large amounts of blanket bog. In such settings, exceptional rainfall and/or disturbance of the peat by human activity can trigger peat landslides – there was for example a large failure at Scalloway in Shetland in 2012 and there were multiple peat landslides in a heavy rainfall event in Shetland in September 2003 (Dykes and Warburton 2008).
On 4 July 2022 a landslide was triggered on the Mid Kames Ridge in Shetland. There is a Youtube video of the setting of the Mid Kames Ridge taken from a drone, including views of the access roads and pads for a large windfarm, which includes 103 turbines across several sites, and which is under construction by Viking Energy. There seems to be little dispute that the peat landslide was associated with the windfarm construction.
The Shetland News has posted an article about the landslide, which includes a remarkable video posted to Facebook by the Stop Viking Energy Windfarm group. This video shows the landslide in motion, carrying an area of crushed rock, presumably a part of the windfarm infrastructure. This still from the video shows the material that failed:-
The video is also on Youtube and should be visible below:-
This is a remarkable example of a peat slide in action – there are few such videos around. The Shetland News reports that the area has been stabilised and some reinforcement has been placed to prevent a recurrence. However, experience says that remediating the site of such landslides is very difficult. The scar from another peat landslide on the Kames Ridge, which occurred in 2015, remains visible.
On 23 June 2022, less than two weeks prior to the landslide Mid Kames Ridge , I published an article in Ground Engineering warning of the risk of peat landslides associated with windfarm development. I said:
“Onshore wind development can pose a real threat to peatlands. If poor ground engineering practices are deployed, large-scale failures can occur, causing massive peat degradation and inflicting a high environmental cost downstream. The development of new wind farms in peatland areas will pose substantial ground engineering challenges.”
Meanwhile, yesterday another landslide occurred on Shetland, triggered by heavy rainfall. Again, it seems likely that this is a peat landslide, although on this occasion it does not seem to have been related to a windfarm. It partially blocked a road at Vidlin Junction. The Shetland News has a photograph:-
Dykes, A.P. and Warburton, J. 2008. Characteristics of the Shetland Islands (UK) peat slides of 19 September 2003. Landslides 5, 213–226 (2008). https://doi.org/10.1007/s10346-008-0114-7