Sinking truths: University of Houston confirms Miami’s coastal subsidence challenges

(Press-News.org) On the barrier islands of Miami, 35 skyscrapers – including Trump Tower III - have sunk as much as eight centimeters, or three inches, into the ground since 2016, and researchers from the University of Houston have played a pivotal role in uncovering the reason why – urban development.  

The findings, published in Earth and Space Science, reveal alarming rates of subsidence – or land sinking – in coastal structures between 2016 and 2023.   

According to the report, "About half of the subsiding structures are younger than 2014 and at the majority of them subsidence decays with time. This correlation suggests that the subsidence is related to construction activities." 

Verifying the data 

Researchers from the UH Department of Civil and Environmental Engineering, led by Assistant Professor Pietro Milillo, verified the findings with the extraordinary accuracy of InSAR, (Interferometric Synthetic Aperture Radar), which can detect changes on the earth’s surface as small as the thickness of a credit card from outer space.  

InSAR is a satellite-based remote sensing method that detects ground movement, even millimetric deformations of the Earth, by comparing the differences in radar signals from two images of the same area taken at different times. 

“We attribute the sinking ground primarily to the weight and vibrations from high-rise construction,” said Milillo. “The phenomenon, described as creep deformation, occurs when sandy layers interbedded within Miami’s porous limestone geology compress under pressure, potentially compromising structural stability. Our work confirmed the spatial and temporal patterns of subsidence in the study. We demonstrated how construction-induced stresses extend well beyond building footprints, revealing risks to surrounding areas up to 320 meters away.” 

The study is a collaboration between the University of Houston and other leading institutions, including the University of Miami, the German Aerospace Center, NASA Jet Propulsion Laboratory and the University of Hannover in Germany. Amin Tavakkoliestahbanati, a graduate student of Milillo’s, supported the team.  

A closer look at the findings  

The study documented subsidence in 35 coastal buildings across Sunny Isles Beach, Bal Harbor and Surfside, with newer structures showing the most significant impacts. In many cases, the subsidence began immediately after construction and decayed over time, but in others, it persisted at a constant rate, potentially signaling ongoing risks.  

The InSAR data revealed that subsidence extends beyond individual buildings to surrounding areas. In regions like Sunny Isles Beach, up to 70% of recently constructed high-rises showed measurable ground sinking, a trend exacerbated by the area’s sandy subsurface geology.  

“Our role as a validation partner underscores the importance of geospatial technology in urban risk assessments,” said Milillo. “By confirming these patterns, we’re helping to develop tools for safer urban planning, particularly in geologically sensitive coastal zones.”  

Implications for coastal urban development  

The findings highlight critical challenges for urban development in coastal regions prone to subsidence. With Miami’s barrier islands already at risk due to sea-level rise, subsidence adds another layer of vulnerability to infrastructure. The study’s authors stress the importance of incorporating geological data and remote sensing tools like InSAR into urban planning to identify and mitigate risks before construction begins.  

The University of Houston’s contributions highlight the broader potential of collaborative research in tackling global challenges, reinforcing the importance of adopting advanced monitoring technologies to protect communities in vulnerable regions across the globe.

A call to action  

The study has sparked discussions about improving construction practices and enhancing long-term monitoring of building stability in coastal zones.  

“This work showcases the transformative power of geospatial science to uncover hidden risks beneath the surface,” Milillo added. “It’s a call to action for engineers, planners and policymakers to work together in creating resilient cities.” 

 

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