Ground sinking affects 28 major U.S. cities

Urban areas across the United States are facing a slow-moving geophysical threat beneath their streets and buildings. This gradual sinking of the ground, known as subsidence, is mostly invisible to the naked eye but affects nearly every major city in the country.

Once seen mostly as a coastal issue tied to sea-level rise, land subsidence is now widespread across the United States. New research shows it is largely caused by groundwater extraction, putting about 29 000 buildings and 34 million people at risk in 28 major cities, including New York, Dallas, and Seattle.

Researchers at Virginia Tech have recently tracked this using satellite radar to spot changes that aren’t visible from the surface. They found that much of this quiet sinking is tied to the ongoing withdrawal of groundwater deep underground. Their aim was to measure subsidence and understand how it impacts the built environment. The results show that in every city, at least 20% of the land is affected. In many places, the impact is more than 65%.

Chicago, Dallas, Columbus, Detroit, Fort Worth, Denver, New York, Indianapolis, Houston, and Charlotte are seeing the most widespread land sinking, with nearly 98% of their land areas affected. Leonard Ohenhen, who led the study, explained that even minor downward shifts in the ground can weaken buildings, roads, bridges, and dams. These small changes add up and contribute to an overall weakening of urban infrastructure.

In cities such as Houston, Dallas, and Fort Worth, more than 70% of the land is subsiding at rates faster than 3 mm (0.12 inches) per year. Houston, for example, is sinking faster than most places. Around 42% of the city is subsiding more than 5 mm (0.19 inches) a year. In 12% of the area of the city, the rate is more than 10 mm (0.39 inches).

Researchers found that Chicago’s land is sinking at an average rate of over 2 mm (0.08 inches) per year. About 10% of the city is experiencing a faster rate, with land subsiding more than 3 mm (0.12 inches) annually.

The study also found that Memphis, Tennessee; San Jose, California; and Jacksonville, Florida showed a slight increase in elevation.

The main catalyst behind the sinking is the pumping of groundwater. As cities draw more from underground aquifers to meet growing demand, the soil above gets compressed and starts to sink. This is a familiar process in hydrogeology, but it’s still largely ignored in how cities plan and build. The sinking doesn’t happen uniformly either. Uneven ground movement known as differential settlement puts extra stress on the urban infrastructure.

To understand how sinking ground might damage infrastructure, researchers looked at a measure called angular distortion. This process shows how much the ground tilts over a certain distance. Even a slight tilt can be a big problem, especially for older buildings or ones that weren’t built to handle that kind of stress. The study also found that although high-risk areas make up only about 1% of urban land in the 28 cities, these areas include over 29 000 buildings. San Antonio, Austin, and Fort Worth have some of the highest concentrations of buildings in these high-risk zones. For San Antonio, it’s about one in every 45 buildings. In Austin, it’s one in 71.

The risks vary from place to place. In New York, uneven sinking shows up around LaGuardia Airport. In Washington, DC, it’s noticeable near East Potomac Park. Las Vegas and Los Angeles have their own trouble spots, shaped by local aquifer levels and how the cities were built over time. All of these areas share a mix of natural conditions and human pressures. Aging infrastructure and heavy groundwater use are key contributing factors.

In some cities, the land is still sinking slowly because massive glaciers once pressed it down and is now settling back over time. This phenomenon is called glacial isostatic adjustment. In others, tectonic shifts or natural sediment compaction contribute. However, the data indicate that roughly 80% of observed urban subsidence is linked to groundwater pumping. In some cities with confined aquifers, taking water from deep underground causes the ground above to sink.

This pattern is especially clear in places like San Diego and New York, where confined aquifers are common. The researchers ran statistical models to see what might happen if water keeps being pumped out. In New York, if groundwater falls to half of what it is now, there’s a 62% chance the ground will sink more than 1 mm (0.04 inches). In San Diego, that probability reaches 70%.

Infrastructure in these areas is constantly under stress. Small shifts in the ground can add up over time, leading to issues like cracked foundations, doors that stick, and uneven pavements. These problems can get worse over the years when combined with other environmental factors such as flooding or extreme heat.

The study pointed out that managed aquifer recharge is a proposed mitigation strategy wherein water is deliberately returned to underground reservoirs to help stabilize the land. Cities also need to keep a closer eye on groundwater use and include subsidence data in their planning decisions.

In areas already impacted, retrofitting infrastructure and implementing stricter building codes could be required. These areas should also limit development in high-risk zones and/or require special building codes that account for ground movement.

References:

¹ Land subsidence risk to infrastructure in US metropolises – Leonard O. Ohenhen, Guang Zhai, et al. – Nature Cities – May 8, 2025 – DOI https://doi.org/10.1038/s44284-025-00240-y – OPEN ACCESS

Harsh Vardhan

My passions include trying my best to save a dying planet, be it through carpooling or by spreading awareness about it. Research comes naturally to me, complemented by a keen interest in writing and journalism. Guided by a curious mind and a drive to look beyond the surface, I strive to bring thoughtful attention and clarity to subjects across Earth, sciences, environment, and everything in between.

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