A recent study has uncovered widespread ground subsidence affecting Miami’s luxury high-rises, raising significant concerns about construction practices and long-term structural monitoring. Using Interferometric Synthetic Aperture Radar (InSAR) technology, researchers analyzed 222 radar images from the European Sentinel-1 satellites, tracking surface displacement from 2016 to 2023. Their findings revealed that 35 buildings along Miami’s barrier islands are experiencing notable ground settlement, with Sunny Isles Beach and Surfside being the most affected areas.
Construction’s Impact on Surrounding Areas
The study, led by the University of Miami, revealed that new construction activities can trigger subsidence up to 320 meters away from building sites, challenging traditional assumptions about construction impact zones. Vertical displacement in affected buildings ranged from 2 to 8 centimeters over seven years, with some structures continuing to sink at a steady rate even years after completion.
This phenomenon is especially pronounced in areas where limestone bedrock contains interbedded sand layers, a geological feature common in northern sections of Miami's barrier islands. Construction vibrations and groundwater shifts during foundation work are believed to initiate long-term settlement processes, impacting both newly constructed and neighboring buildings.
Subsidence Hotspots and Notable Findings
The research identified several subsidence hotspots, including the Trump Towers in Sunny Isles Beach, which sank by 5.8 centimeters over seven years. Two buildings in Surfside also experienced significant settlement, raising concerns in an area still grappling with the 2021 Champlain Towers South collapse.
Additional findings include:
- Bal Harbour buildings showed minor subsidence under 2 centimeters but still require monitoring.
- Sunny Isles Beach exhibited the highest rates of subsidence, with some structures sinking up to 8 centimeters.
“Subsidence in most high-rises slows down over time, but in some cases, it continues at a steady rate,” said senior author Falk Amelung. “This suggests that subsidence could persist for an extended period.”
Trump Towers and Miami’s Luxury High-Rises Face Environmental Challenges
The inclusion of high-profile buildings like Trump Towers highlights the challenges of constructing large structures on Miami’s fragile geology. Built on reclaimed land, the towers exemplify the risks of developing in areas with interbedded sand and limestone layers, underscoring the necessity for more resilient construction practices.
To mitigate risks associated with subsidence, researchers recommend several key measures:
- Zoning regulations: Limit high-density construction in areas with vulnerable geology.
- Resilient infrastructure: Design buildings with shifting ground conditions in mind.
- Transparency: Create a public database to monitor and report building settlement.
- Expanded research: Analyze sediment cores and conduct controlled tests on limestone and sand samples to better simulate subsidence conditions.
“Officials in Florida must recognize the value of continued research on this issue across the state,” said Amelung. “Our hope is to secure funding for advanced studies that will benefit coastal residents and safeguard infrastructure.”
The Role of Miami’s Unique Geology
The limestone bedrock along Miami’s coast, interspersed with sand transported by longshore currents from the Appalachians, creates varied subsidence conditions. This explains why Sunny Isles Beach exhibits higher rates of subsidence than Miami Beach, where sandy layers are less prevalent. Preliminary data also indicates that similar patterns may extend northward to Broward and Palm Beach counties, emphasizing the need for further study.
While current subsidence rates don’t necessarily pose immediate structural risks, experts warn that cumulative effects and differential settlement—where parts of a structure sink unevenly—require further investigation. The researchers advocate for improved monitoring systems to detect long-term trends and support proactive maintenance strategies.
