What Are the Possible Causes of the Miami Condo Collapse?

Engineering and architectural experts said that it might take a long time to piece together what caused the partial collapse of the condo building near Miami, but that there were a few things that investigators would look for: corroded components, an undermined foundation or defects in the construction or design.

“When a building falls downward on itself it’s more likely that there was a loss of support somewhere,” said Abieyuwa Aghayere, a professor of civil, architectural and environmental engineering at Drexel University.

The Champlain Towers South building in Surfside, Fla., was about to undergo extensive repairs for corrosion and concrete spalling, or flaking, as part of a required structural recertification for buildings when they reach 40 years of age. Ocean salts can penetrate structures and begin rusting steel components, in particular rebar that may be improperly protected.

But there are other factors that could make a building vulnerable to collapse. Charlie Danger, who retired as Miami-Dade County’s building chief seven years ago, said unauthorized remodeling could result in someone eliminating a structural support column.

In addition, some experts, including Mr. Aghayere, said a sinkhole or other problems with a foundation could lead to major instability under a building.

Gov. Ron DeSantis of Florida and Mayor Daniella Levine Cava of Miami-Dade County both promised on Friday that there would be a full investigation of the collapse.

“We need a definitive explanation for how this could have happened,” Mr. DeSantis said.

Federal investigators were dispatched to the scene. The National Institute of Standards and Technology, which investigated the collapse of the World Trade Center on 9/11, sent a team of experts to Florida on Friday afternoon to meet with local building officials and engineers.

The federal team will ask about the design of the building, how it may have been modified and what happened before the collapse, according to Sissy Nikolaou, an expert on geotechnical engineering who is part of the group. She said she expects the team’s first visit to last about a week.

“We have to understand the landscape of a disaster,” Dr. Nikolaou said in an interview.

Researchers using space-based radar to examine the flooding potential in the Miami Beach area had noticed long before the collapse that the Champlain Towers South building was subsiding, or on land that was sinking, in ways that neighboring properties were not.

“I was surprised,” said Shimon Wdowinski, an environmental professor at Florida International University. “I didn’t expect to see movement over there. That’s a stable part of the city.”

But Mr. Wdowinski said other areas with even larger amounts of subsidence are often seen in areas that have not had buildings collapse.

There have been other complaints from residents of the Champlain Towers condominium complex. One resident filed a lawsuit over water intrusion that she blamed on poor maintenance. Others complained that nearby construction had sent rumbles through the structure.