Dozens of luxury beachfront condos and hotels in Surfside, Bal Harbour, Miami Beach and Sunny Isles are sinking into the ground at rates that were “unexpected,” with nearly 70 percent of the buildings in northern and central Sunny Isles affected, research by the University of Miami found.
The study, published Friday night, identified a total of 35 buildings that have sunk by as much as three inches between 2016 and 2023, including the iconic Surf Club Towers and Faena Hotel, the Porsche Design Tower, The Ritz-Carlton Residences, Trump Tower III and Trump International Beach Resorts. Together, the high rises accommodate tens of thousands of residents and tourists. Some have more than 300 units, including penthouses that cost millions of dollars.
“Almost all the buildings at the coast itself, they’re subsiding,” Falk Amelung, a geophysicist at the University of Miami’s Rosenstiel School of Marine, Atmospheric and Earth Science and the study’s senior author, told the Miami Herald. “It’s a lot.”
Preliminary data also shows signs that buildings in downtown Miami, Brickell, and along Broward and Palm Beach coasts are sinking, too. Globally, similar subsidence within such a large area has never been reported, the university said in a statement.
Experts called the study a “game changer” that raises a host of questions about development on vulnerable barrier islands. For starters, experts said, this could be a sign that rising sea levels, caused by the continued emission of greenhouse gases, is accelerating the erosion of the limestone on which South Florida is built.
“It’s probably a much larger problem than we know,” Paul Chinowsky, a professor of civil engineering at the University of Colorado Boulder, told the Herald.
Initially, researchers looked at satellite images that can measure fractions of an inch of subsidence to determine whether the phenomenon had occurred leading up to the collapse of Champlain Towers in Surfside, the 2021 catastrophe that killed 98 people and led to laws calling for structural reviews of older condos across the state. The researchers did not see any signs of settlement before the collapse “indicating that settlement was not the cause of collapse,” according to a statement.
Instead, they saw subsidence at nearby beachside buildings both north and south of it.
Surprising findings
“What was surprising is that it was there at all. So we didn’t believe it at the beginning,” Amelung said, explaining that his team checked several sources that confirmed the initial data. “And then we thought, we have to investigate it,” he said.
In total, they found subsidence ranging between roughly 0.8 and just over 3 inches, mostly in Sunny Isles Beach, Surfside, and at two buildings in Miami Beach – the Faena Hotel and L’atelier condo – and one in Bal Harbour.
It’s unclear what the implications are or whether the slow sinking could lead to long-term damage, but several experts told the Herald that the study raises questions that require further research as well as a thorough on-site inspection.
“These findings raise additional question which require further investigation,” Gregor Eberli, a geoscience professor and co-author of the study, which was published Friday in the journal Earth and Space Science, said in a statement. Lead author Farzaneh Aziz Zanjani pointed to the need for “ongoing monitoring and a deeper understanding of the long-term implications for these structures.”
Though the vast majority of affected buildings were constructed years or decades before the satellite images were taken, it is common for buildings to subside a handful of inches during and shortly after construction — a natural effect as the weight of the building compresses the soil underneath.
And sinking doesn’t necessarily create structural issues.
“As long as it’s even, everything’s fine,” Chinowsky said, placing his hands next to each other, “the problems start when you start doing this,” he said, then moving one hand down faster than the other.
But such uneven sinking, known as differential subsidence, can cause significant damage to buildings, he said. “That’s where you can get structural damage,” he said. More research is needed to determine whether the buildings are sinking evenly or not.
An uncertain impact
“Sometimes it can be dangerous, sometimes not – it will have to be evaluated,” said Shimon Wdowinski, a geophysicist at Florida International University, told the Herald. Wdowinski worked on a different study that showed that the land surrounding the Champlain Towers – not the buildings themselves – had been subsiding back in the nineties, though that alone couldn’t have led to the collapse. The National Institute of Standards and Technology (NIST) has yet to release a final report on the cause but a Herald investigation pointed to design and construction flaws as well as decades of maintenance issues.
High-rise building dominate the skyline of the coast of Miami-Dade County, from Sunny Isles Beach down to Miami Beach. A new study by University of Miami researchers shows at least 35 buildings in the stretch have sunk by as much as three inches between 2016 and 2023.
For the 35 buildings shown to be sinking in the University of Miami’s study, he said, the next step is to check the integrity and design plans. “If there is differential subsidence, it could cause structural damage, and it would need immediate attention,” he said.
Cracks in walls, utilities that are breaking, or doors and windows that don’t shut as easily as they used to are all signs of differential subsidence, said Gangarao Hota, a professor of civil engineering and the director of the constructor facilities center at West Virginia University.
“In some extreme scenarios, the buildings at some point sink much more dramatically with time,” he said. If that subsidence is differential, “then it is very, very serious,” Hota said.
Cities react to study
Larisa Svechin, the mayor of Sunny Isles Beach, where more than 20 buildings are affected, said that “my priority is the safety of our residents.” Contacted by the Herald Saturday afternoon, she said she was not aware of any structural issues but called an immediate meeting with the city manager. Following that meeting, she said that all required building inspections are up to date and that “the law also requires inspection records to be posted online and shared with residents.”
Charles Burkett, the mayor of Surfside, told the Miami Herald that he had not heard of the study nor was he aware of any subsidence of buildings. “I’d like to know if it’s unsafe,” he said on Saturday, adding that he will “review [the study] in due time.”
Other officials could not be reached immediately, and several of the affected buildings contacted by the Herald said that management would not be available for comment before Monday.
Some settlement appears to have started right around the time when the construction of new buildings nearby began, and when vibration might have caused layers of sand to compress further – just like shaking ground coffee in a tin will make room for more. The pumping of groundwater that seeps into construction sites could also cause sand layers to shift and rearrange.
Though there appears to be a strong link to nearby construction for some buildings, it is unlikely to be the only explanation for the 35 sinking buildings, as some settlement had started before any construction began nearby, and it persisted after construction ended, the researchers found. “There’s no sign that it’s stopping,” Amelung said of the settlement.
The possible climate connection
Experts also pointed to the impact the emission of fossil fuels and the resulting warming of the climate is having on the overall stability of Miami-Dade’s barrier islands.
For one, rising sea levels are now encroaching on sand and limestone underneath our feet. That could lead to the corrosion of the pillars on which high-rises stand – a serious issue, Hota said, though if that’s the case “there may be a way to salvage these buildings,” by fixing the foundation.
Stronger waves, fresh water dumped by heavier rainfalls and more sunny-day flooding could also add to the erosion of the limestone that all of South Florida is built on, Chinowsky said.
Already a soft rock that is riddled with holes and air pockets, further erosion could destabilize the base of most constructions, Chinowsky said, comparing it to “standing on sand, and someone came with a spoon and started taking the sand out.”
“I would expect that they would see this all throughout the barrier islands and on into the main coastline – wherever there is limestone, basically,” he said. “That’s what makes the whole South Florida area so unique, because of that porous rock, the limestone, all that action is happening where you can’t see it, and that’s why it’s never accounted for to this level,” he said.
This climate report is funded by Florida International University, the John S. and James L. Knight Foundation and the David and Christina Martin Family Foundation in partnership with Journalism Funding Partners. The Miami Herald retains editorial control of all content.
If you have questions for the climate team, please email climate@miamiherald.com
University of Miami researchers say sea rise may be contributing to unexpected subsidence of buildings from Sunny Isles to Miami Beach.
