17 February 2020

Did South Wales suffer a coal waste landslide yesterday?

Posted by Dave Petley

Did South Wales suffer a coal waste landslide yesterday?

Yesterday morning the UK Met Office issued a rare red rainfall warning for South Wales, as a result of Storm Dennis.  This was a prescient act as the rainfall duly triggered extensive flooding and a number of significant landslides. South Wales is a landslide prone environment – the Welsh Valleys have many natural landslides and, of course, many more that are a legacy of the mining coal mining that so dominated this area for many decades.

One particular landslide is of interest, and may be of real consequence.  This occurred close to the village of Tylorstown, at approximately 51.656, -3.434. A part of the event was captured on a video that was posted to the front page of the BBC News website.  There is a version of it on Youtube, though I suspect that this is not the original:-


On Twitter, Owen Griffiths posted a very helpful panoramic image of the site of the landslide at Tylorstown:-

Tylorstown landslide

Panoramic view of the landslide at Tylorstown in South Wales on 16 February 2020. Photograph posted to Twitter by Owen Griffiths.


Based upon that image, I interpret the landslide as occurring on the slope shown in the Google Earth image below:-

Google Earth image of the location of the Tylorstown landslide

A Google Earth image of the possible location of the Tylorstown landslide in South Wales on 16 February 2020.


The origin of the landslide appears to be a spoil heap on the valley wall.  The historic 1920-1940 Ordnance Survey map shows the route of the spoil conveyors from the Tylorstown Colliery (also shown on the map as Pendryrys Colliery) to this location, whilst the 1955-61 map shows spoil at this site:-


The photograph of the site suggests that the failure captured on video was only a small part of a larger failure. We need better images, but on first inspection is appears that a large mass has slipped, leaving the large scar that can be partially seen at the rear of the failure, and that a small part of this slipped and disrupted mass has then turned into the more mobile flow captured on video.

Much more detail is needed on this failure than is available at the moment, but since the clean up after the Aberfan landslide coal spoil tip failures have been rare in Wales.  If (and this is an unknown at this point) this is a coal waste landslide then we need to know why it has occurred.  Is it possible that the new, extreme rainfalls that we are now seeing as a result of global heating are rather greater than had been anticipated when the reprofiling was undertaken?

That is a pressing question that can only be addressed by examining this failure properly.