RIO DE JANEIRO >> A closed rock salt mine belonging to Brazilian petrochemical giant Braskem partially collapsed Sunday in the northeastern coastal city of Maceio, the city’s civil defense authority said.

Video distributed by the authority shows a sudden murky bubbling of the water in the Mundau lagoon in the city’s Mutange neighborhood, reflecting the mine’s rupture.

The area had previously been evacuated and there was no risk to any people, the agency said in a statement. It quoted Mayor Joao Henrique Caldas as saying the mine was expected to stabilize following the partial collapse.

The development came as no surprise to residents in Maceio, where Braskem’s 40 years of rock salt mining has caused the displacement of tens of thousands of people, hollowing out communities.

The company alerted officials on Nov. 28 of the imminent risk the mine could collapse. Land around the mine had been steadily sinking ever since, falling a total of 2.35 meters (7.7 feet) as of Sunday morning.

On Nov. 30, Alagoas state Gov. Paulo Dantas warned of the possible “formation of large craters” following the mine’s collapse and said federal teams would arrive that night as back up.

Local residents were told not to travel near the area and waited anxiously, imagining what damage a collapse would bring to their homes and the rest of the city.

In the first few days after its warning, Braskem sent out regular updates, including possible times at which the mine could collapse. The messages scared local residents, including Carlos Eduardo da Silva Lopes, a student at the Alagaos Federal University.

“It caused the population to be in terror, unable to sleep, worried,” Lopes told The Associated Press by phone Dec. 1.

Rock salt mining is a process of extracting salt from deep underground deposits. Once the salt has been extracted, the cavities left behind can collapse, causing the soil above to settle. Structures built on top of such areas can topple.

Between 1979 and 2019, when Braskem announced the shutdown of its rock salt operations in Maceio, the company operated a total of 35 mines.

Troubles in Maceio began a year earlier, when large cracks first appeared on the surface. Some stretched several hundred meters (yards). The first order to evacuate some areas — including parts of the Mutange neighborhood — came in 2019.

Since then, five neighborhoods have turned into ghost towns as residents accepted Braskem’s payouts to relocate. According to the Brazilian Senate’s website, some 200,000 people in Maceio were affected by the company’s mining activities.

In July, the company reached a $356 million settlement with the coastal city.

“We will continue fighting and demanding responsibility from Braskem, which is the big one responsible for these damages,” the civil defense authority’s Sunday statement quoted the mayor as saying.

Aside from mine 18, which partially collapsed Sunday, Braskem has said it is in the process of filling eight other cavities with sand.

Braskem is one of the biggest petrochemical companies in the Americas, owned primarily by Brazilian state-run oil company Petrobras and construction giant Novonor, formerly known as Odebrecht.