All major American cities are sinking slowly, new research reveals

Comprehensive research Published on Nature Cities I discovered an amazing reality. All of America’s largest metropolitan areas are gradually sinking to the Earth beneath it.

The study analyzed high-resolution satellite data in 28 most populous US cities and found extensive land subsidence affecting urban zones from coast to coast. Coastal cities have long been worried about rising seas, but this phenomenon poses a unique threat to infrastructure across the country as different parts of the city sink at different speeds. With around 34 million Americans currently living in affected areas, the findings call for urgent attention to this slow but potentially destructive danger.

A widespread sinking of cities across America

A research team led by Leonard Ohenhen of the Lamont-Doherty Earth Observatory at the Columbia School of Climate Used advanced satellite technology to map vertical land movements with unprecedented accuracy. Their analysis covered all US cities with a population of over 600,000.

“As cities continue to grow, we will see more cities expand into subsided areas,” Ohenhen explained. “Over time, this subsidence can cause stress on infrastructure that exceeds safety limits.”

The study found that more than two-thirds of their area had been sunk in 25 of the 28 cities surveyed. Of the most affected metropolitan areas, Texas cities dominate the list of fastest regions.

Texas cities lead the subsidence rate

Houston appears as the fastest surrounded major city in the nation, with over 40% of its area exceeding 5 millimeters (about 1/5 inch) a year, with 12% sinking at twice that speed. Some isolated spots descend to 5 cm (2 inches) a year. Fort Worth and Dallas weren’t too late to overall sinking rates.

Other cities that show significant rapid local sinking include New York’s LaGuardia Airport and surrounding areas in Las Vegas, Washington, DC and some parts of San Francisco.

The main perpetrator behind this extensive urban sinking is human activity. Based on county-level groundwater withdrawal data, the researchers determined that groundwater removal for human use is responsible for about 80% of the overall sinking.

Multiple forces driving descent

While excessive groundwater pumps have emerged as the dominant factor in most urban subsidence, several natural forces also contribute to the phenomenon.

• The prolonged effects from the ancient ice sheets that once covered North America still gradually calm part of the landscape
• The weight of a city building may be pushing down the earth beneath it
• Construction of new buildings can destroy the underground stability of surrounding structures
• In Texas, oil and gas extraction exacerbates settlement problems
• Climate change-induced droughts in some regions enhance groundwater extraction

The researchers noted that even cities that exhibit overall stability or slight upward movements could have discriminatory movements in issues where adjacent areas move in different speeds or opposite directions. This uneven movement can create dangerous stress in building foundations and infrastructure.

Risk infrastructure

Perhaps the most concern is the findings of research into building safety. Researchers have identified approximately 29,000 buildings currently in the zone, and differential land movements put them at high or very high risk of structural damage.

San Antonio faces the highest percentage of potential structures, with one in 45 buildings eligible for high risk of subsidence-induced stress. Austin (1 in 71 people), Fort Worth (1 in 143 people) and Memphis (1 in 167 people) are approaching.

Historical analysis of 225 US buildings between 1989 and 2000 found that only 2% were directly attributable to subsidence, but the factors behind 30% of collapse were classified as unknown, suggesting that subsidence could play a greater role than previously recognized.

The eight cities with the largest population living on sinking lands in New York, Chicago, Los Angeles, Phoenix, Houston, Philadelphia, San Antonio and Dallas have experienced more than 90 serious floods since 2000, and may have been exacerbated by changes in topography as the land sinks.

Move towards the solution

What can we do to address this national challenge? Researchers emphasize that potential solutions differ depending on local conditions and certain types of subsidence.

In areas where flooding is of primary concern, mitigation strategies may include land rearing, strengthening drainage systems, and green infrastructure such as artificial wetlands that absorb floods. It may prove effective in zones that experience differential movement and slope risks, renovate existing structures, implement stricter building standards, and limit new construction in high-risk areas.

Researchers suggest that cities should use this new detail to target specific solutions rather than taking an approach of all sizes.

“In contrast to saying that’s the problem, we can respond, deal with it, mitigate and adapt,” Ohenhen said. “You need to move to the solution.”

With climate change likely to intensify droughts in many regions and population growth is likely to increase water demand, experts warn that subsidence rates could accelerate in the coming decades without intervention. This study provides urban planners and policymakers with valuable data identifying vulnerable areas and prioritizing infrastructure protection before critical thresholds are reached.