LandSubsidence GroundwaterDepletion InSARMonitoring UrbanInfrastructureRisk

Sinking Cities: The U.S. Subsidence Crisis

*U.S. cities are sinking at varying rates a new recent study showed. Source: CNBC*

A recent study has revealed a trend affecting the stability of American urban infrastructure: land subsidence. Using high-resolution satellite radar data, researchers identified that all but three of the 28 largest U.S. cities are sinking. In over 65% of these urban areas, the land is subsiding at varying rates, with settlements reaching up to 10 mm per year. This phenomenon impacts nearly 34 million residents and places roads, bridges, buildings, and essential utilities at long-term risk.

The study, published in Nature Cities, emphasized that this is not a localised issue. While Columbus, Ohio was highlighted due to its noticeable rate of subsidence (around 2 mm per year), similar patterns are found in Houston, Phoenix, Denver, New York, and coastal regions like Hampton Roads. In places like Houston and Las Vegas, rates can exceed 5 mm annually due to intense groundwater withdrawal.

Illustration of the average rate of vertical land motion (VLM) across 28 U.S. cities, as analyzed in the study. Each circle is color-coded to reflect the corresponding city’s average VLM rate. Source: Nature Cities

Key Drivers and Risk Zones

The primary driver of urban subsidence is groundwater extraction. As aquifers are depleted without replenishment, the supporting pore spaces collapse, causing the ground above to sink. In addition to human-induced factors, natural processes such as glacial isostatic adjustment continue to affect cities along the East Coast. The effect is gradual and cumulative, resulting in differential settlement that causes cracking in roads, utility failures, and building deformation over time.

Satellite data also showed that over 29,000 buildings are located in high-risk zones. Particularly in rapidly urbanising regions, where infrastructure is expanding on unconsolidated soils, the combined effects of urban load and groundwater loss increase the vulnerability of the area.

a) Map showing the percentage of each urban area affected by land subsidence. Color intensity increases from yellow (>0 mm/year) to deep red (>10 mm/year), indicating more severe subsidence rates. (b) Bar chart comparing the total subsiding land area (blue bars) and affected population (green bars) for each city. Source: Nature Cities

Mitigation and Monitoring Strategies

Researchers recommend a data-driven approach. First, groundwater use must be better regulated to prevent irreversible aquifer compaction. Second, infrastructure planning should account for vertical land motion, incorporating adaptive design and material resilience. Lastly, cities should invest in continuous ground monitoring, using tools like InSAR, to anticipate and mitigate future risks.

Check out the following video for more information on the study findings.