1971 Certej dam failure

The 1971 Certej dam failure was a flood due to the failure of a tailings dam at the Certej mine which led to the death of 89 people. It occurred on 30 October 1971 in Certeju de Sus commune, Hunedoara County, Romania.
Background.
The tailing pond of Certej was used between 1936 and 1971 to hold the cyanide-laced acid tailings resulting from the gold mine exploitation of Certej.
The disaster.
At 4:55 AM, the dam broke for a length of and from the tailings pond, of residue flowed towards the town of Certej, flooding a radius of around around the pond. The flood completely destroyed six apartment buildings, a dormitory building and seven individual houses, resulting in 89 deaths and 76 people being wounded. Due to the early hour, most of the victims were sleeping, which resulted in the high death toll.
Aftermath.
The Romanian Communist authorities announced in the press only 48 deaths, in order to avoid a National day of mourning. The survivors were compensated for the loss of their dwellings, receiving from the state an apartment or construction materials to rebuild their houses.
A governmental commission made out of 16 experts was created to investigate the disaster. Following their investigation, they found that the tailings lost their stability due to the increase in height over the allowed limits. Also, a factor may have been the heterogenous content of the pond, as between 1936 and 1971, various materials were deposited, having different characteristics, leading to a fault slip.
The prosecutors investigated the dam planner and five other people, but eventually they decided to drop all charges, as the disaster couldn't have been easily predicted.