The Aberfan Disaster of 1966 — Prof Dave Petley — 13 July 2020

Dave Petley gave a superb talk to 41 mem­bers, guests, and an unknown number of wives and girl­friends. It was the second highly suc­cess­ful Probus Zoom present­a­tion since COVID-19 lock­down (thanks to Peter, Graham, Richard and Jacko).

Dave is Vice President for Research and Innovation, University of Sheffield. His research focus is inter­na­tional land­slide mech­an­isms and he advises the Hong Kong Government, blogs with the American Geophysical Union and is a Council member of the Royal Geographical Society. He has a great gift for put­ting over dif­fi­cult con­cepts clearly and con­cisely.

There were seven large spoil tips rising up the hill­side and close to the vil­lage of Aberfan, where 116 chil­dren at Pantglas school and 28 adults lost their lives in the infam­ous land­slide of the morn­ing of 21 October 1966 (Fig 1).

Fig 1 Aberfan land­slide 1966

A prim­it­ive rope­way led to a crane at the top, where there had been loose tip­ping for sev­eral years. The tip­ping gang (Fig 2) arrived at the top at 7.30am and found it had sub­sided overnight.

Fig 2 Ropeway and tip­ping gang on the spoil heap

Finding that the tele­phone to the pit below wasn’t work­ing, one of gang walked down to raise the alarm. The crane driver stayed at the top and saw its tip move again, but rising up ini­tially. The solid mass, as it broke free, rotated and “bull­dozed” ahead, caus­ing the ini­tial rise then the down­hill slide. Rotation pulled away solid blocks which then frag­men­ted into a 40000 ton flow onto the vil­lage

Landslides result from a grav­it­a­tional effect on loose spoil, sat­ur­ated by under­ly­ing nat­ural springs within weak gla­cial depos­its. Solid spoil con­verts to a flow of water, sludge and debris, and a rota­tional slide between loose spoil, gla­cial depos­its and under­ly­ing solid bed­rock occurs (Fig 3).

Fig 3 Mechanics of land­slide form­a­tion

The NCB knew of the Aberfan springs (Fig 4), making no earlier attempt to divert the water and fail­ing to anti­cip­ate, mon­itor and rec­tify

Fig 4 Pre-spoil heap topo­graphy of Aberfan and adja­cent hill­side with the springs circled.

They were aware of sim­ilar tips with land­slide poten­tial. Furthermore, uncon­trolled tip­ping on top of loose layers pro­gress­ively weakened the base to facil­it­ate a slide. There were earlier land­slides in the area at Abercynon (1939), Aberfan (1944 and 1963), and Rhondda (1965). The NCB, nation­al­ised in 1946 and headed by Lord Robens, chose to ignore the danger.

The school was inund­ated and the chil­dren at the rear of the school had no chance. Classrooms at the front remained intact and some sur­vived. Parents, many of them miners, attemp­ted to rescue their own chil­dren and others before the more formal rescue effort could begin.

The Tribunal was con­duc­ted by Lord Justice Edmund Davies, who had sen­tenced the Great Train Robbers. He was highly crit­ical of the NCB, in denial until day 65, but par­tic­u­larly its chair­man Lord Robens, whose invest­it­ure at the University of Surrey was coin­cid­ent­ally and cyn­ic­ally on the night of the dis­aster. He chose not to go to Aberfan. However he even­tu­ally made amends by set­ting up the Health and Safety Executive, a world leader.

Removal of tips was recom­men­ded after the Tribunal but the NCB pleaded it would lead to bank­ruptcy. £150,000 was cov­ertly sequestered (!) from the £1m+ dis­aster fund by the NCB. This was even­tu­ally repaid into the dis­aster fund by the Blair Government, but without interest, until Gordon Brown finally repaid in full. Compensation was capped at £500 for each family, Lord Robens claim­ing that they “wouldn’t be able to cope with a larger sum”.

There was another land­slide at Tylorstown in February 2020, due to rota­tional spoil heap fail­ure. Spoil heaps now have mixed own­er­ship and are not neces­sar­ily well-monitored. Degradation and cli­mate change is renew­ing interest in future poten­tial land­slides in Wales.

Landslides are a major prob­lem around the world. Loss of life is rising with time, con­firmed by evid­ence from Dave Petley’s own data col­lec­tion from 2004. Tibet, Brazil and recently Myanmar have had dis­astrous rota­tional land­slides, in the latter case pre­cip­it­ated by unem­ployed jade miners scav­en­ging and dis­turb­ing spoil heaps.

It was a sur­prise to learn there is no book writ­ten on the Aberfan dis­aster, des­pite the emo­tional memor­ies linger­ing on and a detailed sequence in Netflix series “The Crown”. Dave’s retire­ment pro­ject maybe?

Those inter­ested in more of Dave’s work can access:

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Beware the cliffs!