More than 30 luxury hotels and high-rise homes along the beach in South Florida are sinking in unexpected ways, according to a new study.
Scientists at the University of Miami said 35 buildings along a 12-mile stretch from Miami Beach to Sunny Isles Beach have sunk or settled by two to eight centimetres.
About half of those buildings are less than a decade old, according to the study, and in some cases the subsidence could be related to nearby construction.
It is not uncommon for buildings to sink slightly soon after construction, but scientists were surprised by their discovery as some of the changes happened several years later.
"The discovery of the extent of subsidence hotspots along the South Florida coastline was unexpected," lead author Farzaneh Aziz Zanjani said.
"The study underscores the need for ongoing monitoring and a deeper understanding of the long-term implications for these structures."
Communities surveyed included Surfside, where the Champlain Towers South building collapsed in June 2021, killing 98 people.
That collapse is thought to have been caused by reinforced concrete deteriorating due to poor maintenance and flawed design.
Still, that incident highlighted the need to monitor stability, "especially in coastal areas with corrosive environmental conditions", the scientists said.
Limestone is interspersed with layers of sand under the South Florida beach - and this can shift under the weight of high-rises and vibrations from foundation construction. Tidal flows also play a role.
Satellite images used to capture the changes show settling is most noticeable in buildings in Sunny Isles Beach. Preliminary data also suggests sinking or settling along the beaches of Broward and Palm Beach counties, which are further north.
The study was published by the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science.
