A team of mechanical, architectural and environmental engineers, geoscientists, and geoinformation specialists affiliated with several institutions in the U.S. and Germany has found that many of the tall, heavy buildings along the coast of South Florida are sinking into the ground much faster than was expected.

In their study published in the journal Earth and Space Science, the group compared satellite images over several years to learn more about ongoing subsidence along multiple beachfronts.

Prior research has shown that many factors can lead to subsidence, in which the altitude of a given parcel of land declines. Natural causes include water movement, earthquakes and gravity. Manmade causes include the heaviness of the built environment, including large buildings, and activities including fracking and landscaping.

In this new study, the researchers noted that the many tall buildings along many parts of the coast in South Florida appeared to be extremely heavy. They wondered if adding so much weight might be causing the ground beneath them to sink.

To find out, the researchers obtained precise satellite imagery for several of the most popular beaches in South Florida and compared 35 buildings standing on them over time. Modern satellite imagery is so precise it can detect changes in altitude of just a few centimeters. The researchers found that every one of the buildings they measured was sinking, ranging from 2 to 8 cm over the years 2016 to 2023, and that most of them were sinking faster than expected.

The research team also found that there were differences in subsidence between beach areas. The worst, for example, was occurring on Sunny Isles Beach; after that was Surfside, site of the collapse of a 12-story building back in 2021. Miami Beach, they noted, was experiencing the least amount of subsidence.

Because of the building collapse three years ago, the researchers took a closer look at Surfside to find out if subsidence may have been a contributing cause and found no evidence. Even if the building had been sinking, they note, it should not have led to structural damage unless it was sinking unevenly, with one part of the ground under the building sinking faster than another.

They suggest more work is required to determine if that is happening to any of the buildings in South Florida, and if so, to warn their owners.

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