Rothbury landslide: the impacts of a landslide on the local economy

Signs of instability along the B6344 East of Rothbury in Northumberland, UK
The section of the B6344 that is affected by the landslide processes is marked with a red line

On Boxing Day 2012 a landslide started to deform a 300 m section of the B6344 between Rothbury and Weldon Bridge, immediately west of Cragend Farm in Northumberland.

Over the following weeks and months, the landslide continued to move and gradually destroyed the road.

There is now a long detour in place and this puts additional strains on the communities, in terms of extra travel cost, revenue lost and travel time.

Following an appeal for assistance, the government has made funds available to enable the reconstruction of the B6344, but this is reported to run well into 2014.

In summer 2013 the BGS Landslide Response Team visited the site to learn more about the landslide mechanisms involved.

Geology

Signs of instability along the B6344 east of Rothbury in Northumberland, UK

The Carboniferous bedrock of this region mainly comprises sandstones from the Fell Sandstone Group.

East of the landslide site a series of sedimentary rock cycles of the Alston Formation are found, and these are generally covered by substantial glacial till deposits (Devensian).

To the west of the site, also interbedded limestone and mudstone sequences of the Tyne Limestone Formation are found.

The valley of the river Coquet was active during glacial periods and widespread deposits of a glacio-fluvial origin are found, containing a variety of gravel, sand and silt sequences.

These deposits drape the valley sides, reaching elevations some 60 to 80 m above the current stream bed.

At the site of the landslide, the slopes below the B6344 leading down to the Coquet river are formed in these glacio-fluvial deposits and this is likely to have contributed to the failure of the slope.

Rothbury landslide superficial geology map key.
Rothbury Landslide bedrock geology map key.

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Landslides and rainfall

Daily rainfall in Northeast England in 2012 and 2013 showing when the Rothbury landslide took place

The wet summer of 2012 has resulted in an increased incidence of landsliding across Great Britain and rainfall appears to have played an important part in the process leading to the onset of the Rothbury landslide.

Before April 2012 the precipitation over North East England was following a pattern that was drier than the long term average.

However, we then experienced a long series of wet events, at first leading to the ‘wettest drought on record’ where the landscape was catching up with the water being delivered.

But then the rains continued, soaking the landscape and making it much more sensitive to landsliding.

Slope response to rainfall events

Because of the many different ways in which water moves through the slopes of our landscapes, some of these slopes will respond quickly to rainfall events. Others will take a bit longer.

The local geology comprises sandstone and this type of bedrock is capable of allowing water to flow through it.

In the fields below the B6344 several issues and springs have been observed and mapped.

It is therefore likely that, in addition to the direct effects of rainfall, these slopes were also de-stabilised due to the flow of groundwater through the sandstone bedrock and the glacio-fluvial deposits covering this bedrock.

The slope below the B6344 gradually became more and more unstable until, on Boxing Day 2012, it started to move seriously and destroyed the road.

Interestingly, this landslide occurred towards the end of the wet period of 2012/13 as only a couple of months later precipitation conditions started to follow a more ‘normal’ trend.

Rothbury landslide gallery

Contact the Landslide Response Team

British Geological Survey
Keyworth
Nottingham
NG12 5GG
E-mail: Landslides team
Telephone: 0115 936 3143
Fax: 0115 936 3276