Recent reporting by the Miami Herald and a new peer-reviewed satellite radar study have drawn attention to subsidence patterns affecting parts of South Florida’s barrier islands. The findings are likely to be of interest to geotechnical engineers working in coastal environments, particularly those dealing with carbonate geology, groundwater interactions, and heavily loaded urban sites.
While ground movement does not automatically imply structural distress or unsafe conditions, the combination of investigative journalism and remote sensing data provides a useful case study in how subtle deformation can be identified and interpreted.
Background
The Miami Herald recently published an in-depth article examining ground movement and settlement trends affecting high-rise buildings along portions of Miami Beach and Sunny Isles Beach.
Link: Miami Herald article on coastal subsidence and high-rise development
The reporting draws on public records, geotechnical reports, and expert commentary to describe how parts of South Florida’s barrier islands appear to be experiencing gradual downward movement. The article notes that development in these areas has accelerated over the past two decades and that subsurface conditions are complex, consisting of layered sands, limestone, and variable groundwater conditions.
Importantly, the reporting does not conclude that specific buildings are unsafe. Instead, it highlights the growing availability of data that can reveal long-term ground movement patterns that might otherwise go unnoticed.
Related Research Using Satellite Radar
The reporting seemed to be based in part or at least inspired by a 2024 paper published in Earth and Space Science which presents a detailed analysis of vertical land motion along South Florida’s barrier islands using satellite-based Interferometric Synthetic Aperture Radar, or InSAR.
Link: InSAR Observations of Construction-Induced Coastal Subsidence on Miami’s Barrier Islands
Zanjani, F. A., Amelung, F., Piter, A., Sobhan, K., Tavakkoliestahbanati, A., Eberli, G. P., Haghighi, M. H., Motagh, M., Milillo, P., Mirzaee, S., Nanni, A., & Andiroglu, E. (2024). InSAR Observations of Construction-Induced Coastal Subsidence on Miami’s Barrier Islands, Florida. Earth and Space Science, 11(12), e2024EA003852. https://doi.org/10.1029/2024EA003852
Using satellite data collected between 2016 and 2023, the researchers identified vertical displacements on the order of a few centimeters at dozens of locations, including areas associated with recent or ongoing construction. The study suggests that the observed motion may be related to time-dependent deformation within sandy layers interbedded in the local limestone, potentially influenced by applied loads and changes in groundwater conditions.
The authors also note that other factors, such as tidal groundwater fluctuations and stormwater injection, may contribute to the observed signals. The relative influence of these mechanisms remains an active area of research.
Interferometric Synthetic Aperture Radar, or InSAR, is a remote sensing technique that uses repeated satellite radar passes to measure very small changes in ground elevation over time.
By comparing the phase difference between radar signals collected at different times, InSAR can detect vertical ground movement at millimeter-scale resolution across large areas. This allows engineers and researchers to observe long-term settlement or uplift trends that may not be apparent from conventional point-based monitoring.
For geotechnical applications, InSAR can help identify broad deformation patterns, provide historical context prior to construction, and complement traditional monitoring methods such as survey points, inclinometers, and extensometers.
At the same time, InSAR data must be interpreted carefully. The measurements represent relative motion rather than absolute elevation, and the signals can be influenced by vegetation, surface changes, groundwater conditions, and construction activity. InSAR results are most useful when evaluated alongside site-specific geotechnical data and construction records.
Why This Matters to Geotechnical Engineers
For practicing geotechnical engineers, this story is less about diagnosing specific buildings and more about the broader implications of monitoring and interpretation.
Subtle settlement measured over years does not necessarily indicate a problem. Many foundations are designed to tolerate a degree of total and differential settlement without adverse performance. However, the ability to observe long-term deformation across wide areas introduces new opportunities, and challenges, for interpreting ground behavior in coastal settings.
These datasets also underscore the importance of understanding local geology, construction history, and groundwater management when evaluating vertical movement in carbonate environments.
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