17 November 2020

Mount Eagle: another peat slide in Ireland

Posted by Dave Petley

Mount Eagle: another peat slide in Ireland

Amongst the focus on the major peat slide in Meenbog in the Republic of Ireland over the last few days, it slipped my attention that another event occurred, this time at Mount Eagle in County Kerry.  The Farmers Journal has an article that provides the detail.  The landslide has occurred on a Sitka spruce plantation in a peat bog area of County Kerry on land owned by Coillte, the state owned forestry company.

The best imagery that I have seen has been posted to Twitter by Save Kerry (@SaveKerry):


On this occasion the peat slide appears to have started in the middle of the Sitka spruce plantation.  It has displaced a large amount of bog, and as observed previously movement is shallow, consisting of rafts some of which include upright trees.  The image below is a screenshot showing these rafts:

Mount Eagle peat slide

The Mount Eagle peat slide. Still from a drone video posted to twitter by Save Kerry.


As the above image shows, the deformed land is highly chaotic, without the ordered structure seen in the Meenbog slide.  I suspect that this may indicate that the this is not an area that has been affected by retrogression of the landslide.  I would like to see an image that captures the whole of the source area of the Mount Eagle peat slide.

Downslope, the Mount Eagle peat slide has transitioned into a channelised flow with a long runout, in common with the many other failures of this type that I have described on this siteThere are concerns for drinking water quality and for the ecological impacts downstream.

The trigger for these landslides is undoubtedly the recent heavy rainfall.  The spate of events that we have seen this year so far reflects the periods of extremely wet weather that have occurred over the British Isles in 2020.  But the precise mechanism of the initiation of the failures is not clear.  I think that there is a particular question to be asked about the role that the spruce plantations play in initiating the slides (this may be related to the way that the trees create rafts of material and/or the ways that they change the drainage of the bogs), as well as the impact of wind farm construction in triggering instability.

As I have noted previously, global heating will mean that these prolonged spells of rainfall, and shorter duration high intensity rainfall events, will increase, so we might expect to see more failures of this type.  Blanket bogs are an important habitat in the UK and in Ireland, and of course they are a major carbon store.  Restoration is a very slow and difficult process.  So, in my view, there is an urgent need to undertake research to understand these landslides better, and to ensure that the land is managed properly.  A combination of detailed field monitoring and novel lab testing should yield some fascinating results.