Aberfan Disaster, Wales, 1966
Another example of a sludge flood caused by heavy rain, the Aberfan Disaster was particularly horrific: Of the 144 victims, 116 were children at the village primary school, which was situated directly beneath an unstable hillside heaped with coal mine tailings.
Since the early 1900s, the coal mine in Aberfan had been depositing slag and waste rock on top of an unstable hillside of porous sandstone with underground springs.
After days of heavy rain in October of 1966, a huge section of the waste material liquefied and broke away from the hill, rushing downhill towards Aberfan. Over 10 million gallons of coal slurry slammed into cottages, farms, and the Aberfan Primary School, where children had just arrived for the last day of class before a week-long break.
As a result of the disaster, the British government enacted the Mines and Quarries Act of 1969, aimed at regulating waste heaps from mining operations.