This Date in Safety History: October 21, 1966: The Aberfan Mine Waste Landslide

Until 1966, very few people outside of South Wales had ever heard of Aberfan. But the horror that unfolded over the course of 5 minutes on the morning of October 21, 1966 would bring the peaceful Welsh village to international attention.   

A Disaster 5 Decades in the Making 

The tragedy was literally five decades in the build-up. Over those 50 years, coal mining companies deposited millions of cubic metres of excavated mining debris on the side of Merthyr Mountain, directly above the village. The mountain of loose rock and mining slag rested on top of a layer of highly porous sandstone situated beneath underground springs. Village officials expressed concerns that the debris piles or “tips” might give way, but the mining companies brushed their complaints aside.  

The inevitable disaster occurred on this date in 1966. Several days of heavy rain had caused the sides of one of the largest tips to subside about 3 to 6 metres. At 9:15 AM on a Friday morning, more than 150,000 cubic metres of water-soaked debris broke loose and slid down the mountain at high speed. About 40,000 cubic metres of the liquefied mess smashed into the village, destroying farms, houses and, most horribly of all, the Pantglas Junior School, with almost no warning. The students were just settling into their first lesson of the day when the landslide tore into their classrooms. 

The results: 144 dead, including 116 children.  

Aftermath of Aberfan 

The Aberfan disaster became a source of global attention and outrage. More than 90,000 private citizens contributed to a worldwide disaster fund of £1.6 billion to aid the victims. Later studies would show that more than half the survivors suffered Post Traumatic Stress Disorder and feelings of guilt. In addition to contributing to the knowledge of PTSD, the Aberfan landslide caused the British government to adopt new mines and quarrying safety legislation to restrict the deposit of excavation debris adjacent to residential areas.  

Sadly, Canada didn’t follow the British example. Failure to regulate mine waste would lead to Canada’s own version of Aberfan, the Mount Polley mine disaster, which occurred in BC on August 4, 2014, when a faulty tailings dam released 25 billion litres of water mixed lead, cadmium, arsenic, and other mine wastes and debris into the local watershed. It was and remains Canada’s worst mine waste disaster.