CNN
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Dozens of luxury condominiums, hotels and other buildings in southeast Florida are sinking at an alarming rate, researchers reported in a recent study.
The study, led by scientists at the University of Miami, found that 35 buildings from Golden Beach to Miami Beach sank up to 3 inches between 2016 and 2023. In all, the sunken buildings are home to tens of thousands of residents and tourists, and include the Ritz Hotels – Carlton Residences, Trump Tower III, Trump International Beach Resort, and the iconic Surf Club Towers.
The researchers said the main cause of subsidence is vibration during construction, which can compact soil particles and cause them to settle, resulting in subsidence, or the gradual sinking of land.
The effect is like shaking ground coffee to create more space, study lead author Falk Amelung, a professor of geophysics in the Department of Marine and Earth Sciences at the University of Miami Rosenstiel, told CNN told. But that wasn’t a surprising conclusion.
“It’s not surprising if buildings move during or shortly after construction, because they’re heavy and engineers build with that in mind,” Amelung says, but this continues for years afterward. “It was amazing,” he said.
Researchers began their study in 2021 when the Champlain Towers collapsed in Surfside, Florida. Although researchers detected no signs of subsidence before the Surfside collapse, they did find evidence of subsidence in nearby beachfront buildings and along the shoreline.
They used satellite imagery to track small movements on the earth’s surface, observing specific locations on buildings such as balconies and rooftop air conditioning units, and measuring how they moved over time.
According to a study, nearly 70% of buildings in northern and central Sunny Isles Beach have sunk. Approximately 23% of the structures in these locations were constructed in the past 10 years.
In addition to construction vibrations, daily tides move water toward and away from shore, which can shift the ground and cause buildings on it to sink.
Seismic activity and soil compaction can naturally cause subsidence due to the weight of sediment accumulating over time and heavy buildings compressing the ground, which over many years can be backfilled and create new coastal land. This problem occurs in regions where
The researchers said their findings only raise “additional questions that require further investigation.”
Miami faces the dual threat of land subsidence and rising sea levels due to climate change. These combinations increase the city’s vulnerability to coastal flooding, storm surge, and erosion.
Manuchel Shirzai, a geophysicist at Virginia Tech who was not involved in the study, said land subsidence will exacerbate severe flooding caused by rising sea levels.
“Changes in the relative height of sea levels, whether the land falls or the seas rise, can cause large-scale flooding in an area,” linking urban subsidence to sea level rise. Shirzaei, who recently conducted the study, told CNN.
Brian McNoldy, a climate and weather researcher at the University of Miami who was not involved in the study, said sea levels in the study area have been rising at an average rate of about 2.6 inches per decade over the past 30 years.
McNoldy told CNN that in these particular locations, “buildings are sinking as fast as the sea level is rising, effectively doubling the rate of (sea level rise) in those locations.” he said.
But Sirzaei and Amelung said there was no need to panic, pointing out that the satellite methods used by the researchers allowed them to actively monitor the stability of coastal tall buildings.
“The good thing about land subsidence, as opposed to sea level rise, is that we can take local action to protect us from it,” Sirzaei said. “This technology provides us with data to build an approach similar to healthcare, but targeted at buildings so we can monitor buildings regularly and make decisions before catastrophic events occur. You can do it.”
