Construction activities and complex geology are cited as the cause of subsidence.

At least 35 skyscrapers on Miami's barrier islands have sunk by as much as eight centimeters during the past seven years. The phenomenon, known as subsidence, is linked to construction activities and the complex geology in the city's coastal areas, according to a study conducted by the University of Miami.

Using advanced satellite technology called Interferometric Synthetic Aperture Radar (InSAR), researchers measured vertical displacements of 2–8 cm between 2016 and 2023 in Miami Beach, Surfside, Bal Harbour, and Sunny Isles Beach.

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The issue appears most prominent in newer buildings, with 70% of structures built in the last decade showing signs of sinking. Even older buildings experienced sudden subsidence, particularly those near new construction sites. For instance, the Porsche Design Tower (pictured below), completed in 2016, recorded one of the highest sinking rates.

South Florida's unique geology plays a significant role. The area’s subsurface consists of porous limestone interbedded with sandy layers. These layers are prone to "creep deformation," a slow and prolonged compression of materials caused by the weight of buildings. Researchers believe construction activities exacerbate this process, triggering ground instability that can persist for years.

Additionally, natural factors like groundwater movements and uneven limestone layers contribute to the problem. Differential sinking - where different parts of the ground beneath a building sink at varying rates - poses a risk of structural damage over time, the research says.

Some structures, even those standing at just 18 meters, are showing signs of subsidence, raising concerns for both high-rises and smaller buildings alike.

Subsidence in Miami’s barrier islands isn’t unique, according to Dezeen – Manhattan, New York’s tourist and business hub, is also sinking under the weight of its skyscrapers. But Miami's combination of geology, construction trends, and climate challenges makes its situation especially urgent.

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One unfortunate example is the 2021 collapse of the Surfside condominium, which claimed 98 lives and was primarily attributed to deteriorating concrete. That tragedy underscored the critical need for monitoring building stability and subsidence risks in coastal zones, not just Miami.

Despite the risks, Miami continues to see a construction boom. Projects like the 48-story Five Park skyscraper and the Aman residential tower are underway.

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