A new study has revealed that 35 buildings along the Miami Beach to Sunny Isles Beach coastline are experiencing subsidence, with some areas showing significant effects. The analysis, which examined buildings from 2016 to 2023, found subsidence ranging from two to eight centimeters, particularly in Sunny Isles Beach and Surfside.
Researchers used a satellite-based technique known as Interferometric Synthetic Aperture Radar (InSAR) to create a surface displacement time series. This technique utilizes “persistent radar scatterers” as reference points for measurement, allowing satellites to measure millimeter-scale displacements.
The study suggests that subsidence is caused by the shifting of grains in sandy layers beneath the ground, triggered by high-rise construction and daily tidal flows. The researchers propose that ongoing subsidence may also be influenced by groundwater flow from underground construction and daily tidal flow.
While builders make efforts to minimize construction vibrations, these factors contribute to a gradual, continuous sinking of the land over time. The team aims to secure additional research funding to drill for sediment cores and test the sands and limestone in the lab to replicate the observed processes.
The study’s findings raise questions about long-term damage caused by differential settlement, where different parts of a structure sink at varying rates. To better understand the causes of subsidence, researchers are working on exposing samples to freshwater to investigate potential limestone dissolution from stormwater and whether heavier buildings could be at greater risk.
The discovery highlights the need for ongoing monitoring and a deeper understanding of the long-term implications for coastal high-rises in South Florida. Researchers hope that officials will recognize the value for continued research on this issue across the state and explore how this novel technology can benefit coastal residents.
Source: https://news.miami.edu/rosenstiel/stories/2024/12/new-study-finds-subsidence-hotspots-impacting-high-rise-buildings-in-south-florida.html