(CNN) – City officials say the cause of the partial building collapse in Miami is still unknown, but engineering reports, investigations and residents have shed light on the integrity of the structure as rescuers continue to rush to find survivors.
At least nine people died, 152 are missing and 134 are accounted for in the Champlain Towers South collapse Sunday night, Miami-Dade County Mayor Daniella Levine Cava said during a news conference.
Here’s what we know about the research so far:
2018 report generates alarm: A 2018 report completed by Morabito Consultants, a structural engineering firm, “details significant cracks and breaks in the concrete,” a statement from the firm said Saturday. The group said it provided an estimate to “make extensive and necessary repairs” to the building association. The report did not indicate whether the structure was at risk of collapse. Morabito was again hired by the building’s association in June 2020 for the repair and restoration process, according to the statement.
At the time of the collapse, roof repairs were underway, but concrete restoration had not begun, the firm said, adding that it “exclusively provides” engineering consulting services and does not provide construction-related services.
“We are deeply concerned about the collapse of this building and are working closely with the investigating authorities to understand why the structure failed. As we do so, we also continue to pray for all those affected by this tragic event, ”the firm said in the statement.
One researcher says the condo showed signs of sinking in the 1990s: Shimon Wdowinski, a professor at Florida International University’s Institute of the Environment, told CNN that he determined in a study last year that the Champlain Towers South condo showed signs of sinking in the 1990s. The condo had a rate of subsidence of about two millimeters per year between 1993 and 1999, according to their study. While Wdowinski said this subsidence alone likely wouldn’t cause the condo to collapse, he said it could be a contributing factor. “If one part of the building is moving relative to the other, that could cause some tension and cracks,” he explains.
Residents raised concerns about tremors during the construction of a nearby building: Eliana Salzhauer, one of the three city commissioners for Surfside, Florida, told CNN Sunday night that survivors of the collapse with whom she has spoken they have said they felt tremors during the construction of a nearby building in recent years. Salzhauer said some of the survivors told him they were upset by the shaking of their building that occurred while a skyscraper was being built next door. They told him there were tremors, cracks and water leaks in the garage, he said.
Local leaders are now reviewing the construction protocols: the deadly collapse prompted nearby cities and towns to review their building recertification protocols. Less than 5 miles north of Surfside, the city of Sunny Isles Beach will begin dispatching teams to inspect buildings on Monday after announcing Saturday that they would modify the existing process for building recertification for 40 years, Deputy Mayor Larisa Svechin told CNN .
On Friday, the city of Miami sent a letter urging buildings that are more than six stories tall and more than 40 years old to get an inspection from a qualified structural engineer, Stephanie Severino, Miami’s director of communication, told CNN. They are asked to respond within 45 days with any possible structural concerns.
Boca Raton Mayor Scott Singer told CNN in an email Sunday that his city is creating “stricter standards for building certifications” following the Surfside collapse.