Dozens of condominiums, hotels and other luxury buildings in Southeast Florida are sinking at a surprising rate, researchers reported in a recent study.
He studyled by scientists at the University of Miami, found that 35 buildings from Golden Beach to Miami Beach sank up to three inches between 2016 and 2023. The sinking buildings, which together house tens of thousands of residents and tourists, include the Ritz-Carlton. Residences, Trump Tower III, Trump International Beach Resorts and the iconic Surf Club Towers.
Researchers said the main cause behind the subsidence was construction vibrations, which can cause soil particles to compact and settle, resulting in gradual subsidence of the land.
The effect is like shaking coffee grounds to create more space, Falk Amelung, lead author of the study and professor of geophysics in the Department of Marine Geosciences at the University of Miami’s Rosenstiel School, told CNN. But that was not the surprising conclusion.
“It’s not a surprise if buildings move during construction or immediately after construction, because it’s heavy and engineers take that into account when they build,” Amelung said, but this continues for years afterward, “that was surprising.”
The researchers began the study when the The Champlain Towers collapsed in Surfside, Florida, in 2021. Although researchers did not detect any signs of subsidence before the Surfside collapse, they did find evidence of it in nearby beachfront buildings and along the coast.
Using satellite images to track small movements of the Earth’s surface, they looked at specific points on buildings, such as balconies and rooftop air conditioning units, and measured how they moved over time.
According to the study, almost 70% of buildings are sinking in north and central Sunny Isles Beach. About 23% of the structures in these locations were built in the last decade.
In addition to construction vibrations, the daily tides that move water to and from the shore can also cause the ground to shift and the buildings on it to sink.
Seismic activity or soil compaction, either naturally from the weight of sediments that accumulate over time or from heavy buildings putting pressure on the ground, can also cause subsidence, a problem in areas where along Over the years, new coastal lands have been created by filling them with sediment.
Researchers say The findings only raise “additional questions that require further investigation.”
The oceans rise and the coasts sink
Miami faces a double threat: land subsidence and sea level rise due to climate change, a combination that increases the city’s vulnerability to coastal flooding, storm surge and erosion.
Land subsidence exacerbates severe flooding due to rising sea levels, said Manoochehr Shirzaei, a geophysicist at Virginia Tech who was not involved in the study.
“Any change in the relative rise of sea level – whether the land falls or the sea rises – would cause significant flooding in the region,” said Shirzaei, who recently made a study linking sinking cities and rising sea levels told CNN.
Sea level rise in the study area is developing at a rate of about 2.6 inches per decade on average over the past 30 years, said Brian McNoldy, a climate and weather researcher at the University of Miami, who did not participate in the study.
In these specific locations, McNoldy told CNN that “buildings are sinking as fast as the ocean is rising, effectively doubling the rate (of sea level rise) at those sites.”
But Shirzaei and Amelung said there’s no reason to panic, noting that the satellite method used by researchers can now proactively monitor the stability of coastal skyscrapers.
“The good thing about land subsidence, as opposed to sea level rise, is that we can take local steps to protect against it,” Shirzaei said. “This technology gives us the data to create a healthcare-like approach, but for buildings, so we can monitor them periodically… and make decisions before a catastrophe occurs.”
