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Study Finds Ground Beneath Major US Cities Is Sinking at Scale That Threatens Infrastructure
A pair of studies published in Nature Cities in 2025 has found that land is sinking beneath all 28 of the most populous cities in the United States, with at least 20 percent of urban land area affected in every city examined. The research, which drew on satellite-based geodetic measurements collected between 2015 and 2021, estimates that approximately 34 million people in those cities are living on ground that is actively subsiding, raising significant questions about the long-term structural integrity of the infrastructure built upon it.
The studies identify groundwater extraction as the dominant driver of the sinking, as the removal of water from underground aquifers causes the surrounding soil to compact and the surface to drop. Additional factors include the weight of buildings and infrastructure itself, drainage of organic soils, and in coastal areas, the loading effects of reclaimed land. The rates of subsidence vary considerably by location and geology, but the researchers found that in the most severely affected zones, ground was sinking at rates exceeding 10 millimetres per year, a pace sufficient to accumulate structurally significant displacement over the lifetime of a building or bridge.
The infrastructure implications are substantial. Roads, pipelines, rail lines, and building foundations in subsiding areas experience progressive differential settlement, meaning that different sections of the same structure move at different rates and by different amounts. Over time, this creates stress concentrations that lead to cracking, joint failure, and in some cases structural instability. The studies note that subsidence-related infrastructure damage in US cities has historically been underestimated in maintenance planning, in part because the ground movement causing the damage is invisible to routine visual inspection.
The publication of the research coincides with a broader shift in how infrastructure managers and insurers are thinking about ground risk. Satellite geodesy, and in particular InSAR processing of synthetic aperture radar data, has made it possible to map subsidence rates across entire urban areas at consistent intervals, providing a spatial picture of ground behaviour that was not obtainable through conventional monitoring approaches. Several city and state agencies in the United States have begun piloting satellite-based monitoring programmes as a result of findings like those presented in the Nature Cities studies.
The research reinforces a point that has been building in both the geotechnical and infrastructure management communities for some time: ground movement is not an isolated hazard confined to unstable hillsides or mining regions. It is a pervasive, low-visibility risk embedded in the foundation conditions of urban infrastructure worldwide, and one that demands monitoring tools capable of matching its spatial scale.