The Aberfan disaster 1966

If you were ever to label a disaster as "Horror", the Aberfan disaster would truly be in the top 5 of the 20th century. Not just because it happened, but because it should have never happened to begin with, and the guilty walked free with not even so much as a smack on the wrist for killing so many!
The Aberfan disaster occurred on October 21, 1966, near Merthyr Tydfil, Wales. A coal mining company had built a mountain of slag (soggy residue remaining in the process of mining coal, the texture of wet cement). Building up of "slag heaps" is a normal part of the process of coal mining. They are normally built up on flat ground, and are limited in height due to the consistency of the slag. Eventually, the water drains out, and the slag heap hardens to an extent. But, the Aberfan slag heap was built up monstrously on the side of a mountain, overlooking the village below.
The mining company had been warned & fined dozens of times over the continuously growing Goliath of slag. Yet, the mining company ignored the warnings & paid off officials, and kept building up the slag heap.
On October 21, the already dangerously saturated mountainside of slag was inundated with an unusually heavy rain, collapsed like a monstrous black avalanche, racing downhill, burying nearly half the town, including the local schoolhouse, killing 116 children & 28 adults.
This disaster culminated in the mining company being held responsible for the disaster & ordered to pay millions to the survivors, only to have that ruling overturned. In spite of all of the documented warnings & fines, the mining company was absolved of any wrongdoing, and the slag collapse was labelled a natural disaster. No survivor ever received justice, compensation, or anything. And, the mining company continued their unsafe practice, and began rebuilding up the slag heap, only to have it collapse again, just a few months after the first. The town was nearly wiped out, but there are a few families that have remained, living in fear.