Aberfan disaster: 60 years after the tip that was known about

Shortly after 9am on 21 October 1966, a colliery spoil tip on the mountainside above the village of Aberfan, near Merthyr Tydfil in south Wales, collapsed and slid down as a slurry. It buried Pantglas Junior School. Of the 144 people killed in the Aberfan disaster, 116 were children and 28 were adults, according to the official inquiry. Inside the school, 109 children and five teachers died, from 240 pupils who had arrived minutes earlier for the last day before the half-term holiday.

Six decades after the Aberfan disaster the record of that morning has not changed, and neither has the part that is hardest to read: the failures were known, written down, and left in place.

Springs on the map, warnings in writing

Tip 7, the spoil heap that slipped, was started in 1958 and stood about 111 feet high when it failed. It was built partly on ground where springs emerged, against the National Coal Board's own procedures, the inquiry found. The springs were not a secret: the record notes that they had been marked on Ordnance Survey and geological maps since 1874.

Documents gathered for the inquiry show that between July 1963 and March 1964 Merthyr Tydfil County Borough Council wrote to the NCB about the "Danger from Coal Slurry being tipped at the rear of the Pantglas Schools". Meetings followed in early 1965, at which the Board agreed to act on the blocked pipes and drainage ditches that were flooding the Pantglas area. According to the inquiry's account of the papers, no action had been taken by October 1966.

There had also been a rehearsal of the disaster three years earlier. In 1963 part of Tip 7 shifted. The NCB said the movement was not a slide but a "tailings run", a runoff from the surface of the tip, and that its stability was unaffected. Tipping of fine tailings stopped, but ordinary spoil kept arriving.

Nine minutes

Rain did the rest. During the first three weeks of October 1966, 6.5 inches fell on Aberfan, nearly half of it in the third week. Overnight on 20 to 21 October the peak of Tip 7 dropped 9 to 10 feet, and the rails carrying spoil to the summit fell into the hole. The morning shift found the damage at 7.30am.

The men reported it at the colliery. A supervisor for the tips came out. The decision, as the inquiry recorded it, was that no further work would be done that day and that a new tipping position would be chosen the following week. At 9.15am a mass of water-saturated spoil broke away. A consulting engineer, G. M. J. Williams, told the tribunal that the saturated material liquefied as it moved and pulled the rest of the saturated tip with it: this was the "dark glistening wave" witnesses saw burst from the foot of the tip. Around 140,000 cubic yards of spoil travelled up to 700 yards down the hill, at 11 to 21 miles per hour, in waves 20 to 30 feet high.

The verdict, and what followed it

The tribunal into the Aberfan disaster was appointed on 25 October 1966 and chaired by Lord Justice Edmund Davies, sitting with the civil engineer Harold Harding and Vernon Lawrence. It took evidence in public for 76 days and heard 136 witnesses before publishing its report on 3 August 1967. Its finding was blunt: blame for the disaster rested on the National Coal Board, shared in varying degrees with its headquarters, its South Western Divisional Board and certain individuals. Nine employees were censured. Its papers are held by the National Archives. The Board's legal liability to pay compensation was, the report said, "incontestable and uncontested".

The inquiry's introduction carries the line that has kept its force: the disaster "could and should have been prevented", and the report told "not of wickedness but of ignorance, ineptitude and a failure in communications". The tribunal also criticised the Board's chairman, Lord Robens, for making misleading statements about what the NCB knew of the springs on the hillside. Neither the Board nor any of its employees was prosecuted, and the organisation was not fined.

What changed came later, and in law. The Mines and Quarries (Tips) Act 1969 put spoil tips under statutory regulation. The Aberfan Disaster Memorial Fund, opened on the day of the disaster, received nearly 88,000 contributions totalling 1.75 million pounds, of which 150,000 pounds was later taken to pay for clearing the remaining tips. That money was repaid in 1997 without the interest it would have earned, and in 2007 the Welsh Government gave 1.5 million pounds to the memorial charity and 500,000 pounds to the education charity as an inflation-adjusted return of what had been taken.

The cost to the village is still being counted. Many residents developed medical problems after the Aberfan disaster, and about half of the survivors have experienced post-traumatic stress disorder at some point in their lives, the record shows. In 2022 the cemetery, the memorial garden and the tip and its slide path were listed by Cadw as a Grade II* site of special historic interest, described in the register as being of "great national importance and meaning".

Sixty years on from the Aberfan disaster, the useful part of the anniversary is not the grief, which belongs to Aberfan, but the sequence: a known spring, a written warning, an internal assurance, an inquiry that named every failure, and no prosecution. The village's name is now attached to a date. In Wales, nobody needs the date.

More reporting on industrial risk, public accountability and the communities left to carry the aftermath sits in the Deep Dives and World & Society sections.