A new study of 28 most populous US cities finds that everything is sinking to some degree. The city contains much of the interior, not just the coastal ones where relative sea levels are of concern. Furthermore, using new granular data, this study found that some cities were sinking at different speeds in different locations, or sinking at one location and rising elsewhere, potentially introducing stress that could affect buildings and other infrastructure. The authors state that large-scale ongoing groundwater extraction is the most common cause of movement on these lands, but other units work in several locations.
This survey was published this week Journal in the natural city.
“As cities continue to grow, we will see more cities expand into subsided regions,” the Reading author said. Leonard OhanhenPostdoctoral researcher at Columbia School of Climate Lamont-Doherty Earth Observatory. “Over time, this subsidence can cause stress on infrastructure that exceeds safety limits.”
Fast-sinking coastal metropolis such as Jakarta, Venice and New Orleans have already attracted a lot of attention, with multiple recent studies showing more locations Along the East Coast of the US And elsewhere is calming down. However, most studies rely on relatively sparse data spread over a wide area to draw a wide picture.
Looking at all US cities with populations over 600,000, the new study uses recent satellite data to map land movements perpendicular to millimeters of a grid of just 28 meters (approximately 90 feet) squares. The authors found that in 25 of the 28 cities more than two-thirds of their area have sunk. Overall, around 34 million people live in affected areas.
The fastest city is Houston, with over 40% of its area exceeding 5 millimeters (about 1/5 inch) a year, with 12% sinking at twice that speed. Some local spots fall to 5 cm (2 inches) a year. Two other Texas cities, Fort Worth and Dallas, aren’t too late. Localized fast zones elsewhere include areas around Lagardia Airport in New York, as well as parts of Las Vegas, Washington, DC and San Francisco.
In addition to measuring surface elevator changes, researchers analyzed county-level groundwater withdrawal of affected areas. Correlating this with land movement, they determined that groundwater removal for human use was the cause of 80% of the overall sink. Generally, this occurs when water is withdrawn from an aquifer made up of fine grain sediments. Unless the aquifer is replenished, the pore space previously occupied by water will eventually collapse, leading to compression below, allowing it to sink onto the surface. In Texas, the issue is exacerbated with oil and gas pumps, the paper says.
Researchers say the continued population growth and water usage combined with climate-induced droughts in some regions are likely to exacerbate settlement in the future.
In some areas, the forces of nature are at work. In particular, the weight of the towering ice sheet, which occupied most of North America’s interior until about 20,000 years ago, inflated the land along the edge upwards. Even today, as the ice has passed, some of these bulges still subside at a rate of 1-3 millimeters each year. The cities affected include New York, Indianapolis, Nashville, Philadelphia, Denver, Chicago and Portland.
Even the vast weight of a building may be at the expense of it. One 2023 study More than one million buildings in New York have pushed the planet so hard that they are contributing to the ongoing subsidence of the city. a More recent separate studies Some buildings in the Miami area were found to have sunk in part due to underground disruption caused by the construction of new buildings nearby.
A new study found that eight cities (New York, Chicago, Los Angeles, Phoenix, Houston, Philadelphia, San Antonio and Dallas) account for more than 60% of people living on the sinking land. In particular, these eight cities have seen more than 90 serious floods since 2000, perhaps driven in part by lowering the topography.
Houston, Texas, is the fastest city in the country, with over 20 millimeters of region sinking annually. Warm colors mean bigger sinks. Click to view data and features. Data is generalized to a 500-meter grid. (Maps by Jeremy Hinsdale, Ohenhen et al., Nature Cities 2025.)
Another important finding: in some cities, adjacent areas sink at different speeds, or even sinking while others rise. Upward movements possibly caused by rapid charging of aquifers near rivers or other sources. (The uplifts in certain regions are actually more than a supplement to the overall sink of the three cities: Jacksonville, Florida, Memphis, Tennessee, and San Jose, California)
As the authors point out, when the entire urban area is up and down evenly at the same speed, differential movement is an issue, as it minimizes the risk of stress on building foundations and other infrastructures. However, if the structure is exposed to an array of uneven vertical motion, it can experience dangerous slopes.
“Unlike flood-related risks of subsidence, risks only appear when land rise with a high rate of subsidence falls below the critical threshold, but even slight changes in land movement can cause subsidence-induced infrastructure damage,” the author writes.
The study found that only about 1% of the total land area of ​​28 cities are within zones where differential movements can affect buildings, roads, rails and other structures. However, these regions tend to be in the dense urban cores, and currently contain around 29,000 buildings. The most dangerous city in this respect is San Antonio, and researchers say one of the 45 buildings is affected by a high risk. Austin (1/71); Fort Worth (143) and Memphis (167).
The results of the individual structures of these regions are unknown. Perhaps more detailed research is needed, Ohenhen said. Previous studies of 225 US buildings collapse between 1989 and 2000 found that only 2% were directly attributable to subsidence. However, the factors behind 30% have been designated as unknown, suggesting that subsidence may have played a greater role, according to a new study.
This paper concludes that cities should use this new information to focus on solutions. They say in many places, flooding can be reduced with green infrastructure such as flooding, strengthening drainage systems and artificial wetlands that absorb floods. Cities that are susceptible to slope risk can focus on remodeling existing structures, integrating land movements into building standards, and limiting new buildings in most threatened areas.
“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.”
The study was co-authored by researchers at Virginia Tech, an applied science research institute at the University of California, Berkeley, Texas A&M University, University of Colorado Boulder, Brown University, and United Nations University.
