Collapsed Miami condo had been sinking into Earth as early as the 1990s, researchers say - USA TODAY

A Florida high-rise that collapsed early Thursday was determined to be unstable a year ago, according to a researcher at Florida International University.The building, which was constructed in 1981, has been sinking at an alarming rate since the 1990s, according to a study in 2020 by Shimon Wdowinski, a professor in the Department of Earth and Environment.When Wdowinski saw the news that the Champlain Towers South condominium in Surfside collapsed, he instantly remembered it from the study, he said.“I looked at it this morning and said, ‘Oh my god.’ We did detect that,” he said.Graphics: Closer look at the Florida building that partially collapsedWdowinski said his research is not meant to suggest certainty about what caused the collapse. In his experience, even the level of sinking observed in the 1990s typically results in impacts to buildings and their structures, Wdowinski said. The management company paid for damages in the earlier case, according to records.Cracked walls or shifting foundations can be clues that sinking has affected the stability of a structure, according to Matthys Levy, a consulting engineer, professor at Columbia University and author of “Why Buildings Fall Down: How Structures Fail.”Residents of the building might have noticed changes, he said.“Had there been changes in the building? You kind of have to know if there's an issue first before you start monitoring it.”There is always concern for structures built on reclaimed land, according to Levy.Reclaimed land, whether landfill or wetlands, can compact over time, leading to shifts in the ground under the building and potentially to the foundation.“A milliliter may seem like a small number, but when you add them up over many years, it becomes a big number,” Levy said.The building could have been especially vulnerable if the ground it was situated on was sinking at different rates, causing differential settlement.“The fact that one part of it is still standing is important.