Photo credit: phys.org
South Florida’s Coastal Buildings: A Growing Problem of Subsidence
A multidisciplinary team comprising mechanical, architectural, and environmental engineers, alongside geoscientists and geoinformation specialists from various institutions in the U.S. and Germany, has uncovered concerning trends regarding the stability of tall buildings along South Florida’s coastline. Their research indicates that these structures are sinking into the ground at rates that surpass previous expectations.
The findings were detailed in a study published in the journal Earth and Space Science, where the team utilized years of satellite imagery to investigate subsidence patterns across several beachfront locations.
Previous studies have identified diverse factors that can lead to land subsidence, a phenomenon characterized by the downward shift of Earth’s surface. These include natural causes such as groundwater depletion, tectonic shifts, and geological processes, as well as human-induced factors like the weight of large buildings, land use changes, and activities such as fracking.
The researchers focused on the significant weight of the tall structures prevalent in South Florida. They hypothesized that this might be contributing to the subsidence observed beneath them. To investigate this, they acquired high-resolution satellite images of numerous popular beaches and assessed 35 prominent buildings over time. The advanced satellite technology enabled them to detect changes in elevation as minute as a few centimeters. The analysis revealed that all monitored buildings were experiencing subsidence, with measurements indicating a downward shift ranging from 2 to 8 cm between 2016 and 2023. Alarmingly, many of these buildings were sinking at a rate above what had previously been anticipated.
Variability in Subsidence Rates
The study also highlighted discrepancies in subsidence rates across different beach areas. The most severe sinking was identified at Sunny Isles Beach, followed by Surfside, which garnered attention due to the tragic collapse of a 12-story building in 2021. In contrast, Miami Beach showed the least amount of subsidence.
In light of the Surfside incident, the researchers conducted a thorough evaluation to determine if subsidence could have played a role in the collapse, but they found no conclusive evidence linking the two. They noted that even if the building were to sink, such changes would only pose a risk to structural integrity if uneven subsidence occurred, causing one area of the foundation to sink more rapidly than others. The team emphasized the need for further research to assess whether any of the other buildings in the region are experiencing similar uneven sinking, which could warrant immediate attention and caution for their owners.
More information: Farzaneh Aziz Zanjani et al, InSAR Observations of Construction‐Induced Coastal Subsidence on Miami’s Barrier Islands, Florida, Earth and Space Science (2024). DOI: 10.1029/2024EA003852
Source
phys.org