A recent study conducted by the University of Miami has discovered that 35 coastal buildings between Miami Beach and Sunny Isles Beach are sinking at a rate of 2 to 8 centimeters over recent years. This research, spearheaded by scientists from the University's Rosenstiel School of Marine, Atmospheric, and Earth Science, was published in the journal Earth and Space Science.
The Study's Revelations
Utilizing satellite radar technology to measure displacement, the study focused on the period from 2016 to 2023. Researchers monitored fixed features of the buildings such as balconies, rooftop air conditioning units, and walkways. The satellite technology enabled the detection of "millimeter-scale displacements," offering a precise analysis of this phenomenon.
Among the areas studied, Sunny Isles Beach exhibited the most significant subsidence, followed by Surfside. Notably, Surfside was the site of the tragic collapse of the Champlain Towers South apartment building in 2021, which resulted in the deaths of nearly 100 people. The study clarified that in Surfside, no signs of displacement were detected before the collapse, indicating that sinking was not the cause of the disaster.
Farzaneh Aziz Zanjani, the lead researcher, highlighted the unexpected nature of the widespread subsidence along Florida's southern coast, emphasizing the importance of continuous monitoring and a deeper understanding of the long-term implications for these structures.
Factors Contributing to the Sinking
The study attributes the sinking to several factors, including the shifting of sand grains in the layers beneath the buildings due to their weight and construction vibrations, daily tidal flows, and potential fracturing of the underlying limestone. Professor Gregor Eberli, a co-author of the study, explained that while limestone in Florida is generally stable, sand naturally compacts over time. "Sand layers will always compact slightly over time. It's a very slow movement, and minor subsidence does not compromise structural integrity," he detailed.
Eberli also pointed out that ground stability varies, explaining that "the more solid limestone in the southern study area does a better job supporting heavy buildings than the softer ground to the north."
Impact and Community Response
The study emerges in the wake of the Champlain Towers South tragedy, prompting increased scrutiny of infrastructure in southern Florida. Although the collapse was not related to subsidence, researchers warned that construction-related vibrations in Surfside have led to sinking in other buildings.
Surfside Mayor Charles Burkett expressed concern and stated his intention to present the study at the upcoming municipal commission meeting. In contrast, Eberli emphasized that while there is no cause for alarm, the study should encourage ongoing monitoring efforts. "The study should lead to more monitoring and additional research methods. I wasn't surprised it happened, but the rates aren't particularly large," he concluded.
Though the current data doesn't pose an immediate threat, experts stress the importance of implementing consistent monitoring measures to ensure the future safety and stability of these structures.
Understanding Coastal Subsidence in Florida
What methods were used to detect building subsidence in the study?
The study utilized satellite radar technology to measure millimeter-scale displacements in the buildings, focusing on fixed elements like balconies and rooftop air conditioning units.
What are the main causes of building subsidence identified in the study?
The sinking is attributed to factors such as the shifting of sand grains due to building weight and construction vibrations, daily tidal flows, and potential fracturing of the limestone below.
Is the subsidence a threat to the structural integrity of the buildings?
The study suggests that minor subsidence does not compromise structural integrity, as the movement is slow and the limestone generally supports the buildings well.