
“Considered the largest calamity of the century, the floods of ’75 happened between the 17th and 18th of July, and left 80% of Recife under water. Another 25 municipalities of the Capibaribe basin were also affected. One-hundred and seven people died and another 350 thousand were uprooted from their homes.
In the capital as well as inland, 1,000 kilometers of railway tracks were destroyed, bridges came apart and houses were taken away by the waters. Just in Recife, 31 neighborhoods, 370 streets and plazas were submersed; 40% of the gas stations in the city were inundated; the power was cut for 70% of the area; almost all the hospitals in Recife were also underwater, with a food bank that made up part of Hospital Pedro II having been sacked. Via land, Recife was isolated from the rest of the country for two days.
The governor Moura Cavalcanti declared a state of public emergency in the capital and in nine inland municipalities. The president of the Republic, on a national TV station, announced measures to bring aid to the worst off Pernambucan cities. In Recife, the rise in the water level reached it’s high point at 4AM on the 18th of the month.

(a post-flood gov’t pamphlet)
On the morning of the 21st, when the waters lowered and the population began to return to normal life, panic took over the streets of Recife, due to a rumor that the Tapacurá dam had burst and the entire city would be wiped away.
Everything happened at 10 o’clock: all of a sudden, large groups of people ran from one side to the other without knowing where to go; women fainted; drivers no longer respected traffic lights nor cars coming in the opposite direction; transit cops abandoned their posts; several people were ran over; banks, businesses and the central post office closed their doors; at the Barão de Lucena Hospital people jumped from the second floor; while the rumor spread by word of mouth.
In the Governor’s Palace, upon realizing what was happening, the governor Moura Cavalcanti stated: “Now there’s no more tragedy, now there’s mortality”. Radio stations immediately divulged insistent denials. The Military Police gave out an official notice that they would arrest anyone caught spreading the false rumor.
The Federal Police announced that they were investigating the origin (never to be discovered) of the rumor. Panic lasted close to two hours, but remained at its high point for close to 30 minutes. More than 100 people were attended to at emergency service stations set up by the hospitals.
After the panic, technicians from the Water Supply Company stated that the rupture in the Tapacurá Dam (which has capacity for 94 million cubic meters of water) would have brought about unseen consequences for the city of Recife.” - Pernambuco A-Z
Special thanks to my source on Tumblr, Made in Recife via Recifense. If you’d like more info (in PT), check out these stories on UOL (1 and 2). I also recommend reading Vanessa’s account of the floods in the comments section.