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The Independent
09-05-2025
- Science
- The Independent
Fastest sinking city in the US is revealed in new study and it's not in Florida
A new study reveals that one major U.S. city is sinking faster than any other—and it's not in the Sunshine State. Researchers from the Columbia Climate School's Lamont-Doherty Earth Observatory published their findings in the Nature Cities journal on Thursday. The study focused on the 28 most populous cities across the country, each home to more than 600,000 Americans. Recent satellite data was used to monitor land movement down to the millimeter. In a staggering twist, the study's authors found that in 25 of the cities, two-thirds or more of their land was sinking. All of the 28 cities experienced some degree of land subsidence. One city had sunk lower than any other: Houston. According to the study, approximately 40 percent of Houston's area subsided more than five millimeters per year, and about 12 percent was sinking at double that rate. Some localized spots were found to be sinking as much as 50 millimeters per year. Other major Texas cities were also found to be sagging deeper into the earth. Dallas and Fort Worth were found to be experiencing subsidence at rates above three millimeters per year in 70 percent of their total areas. Ten percent of the area in Chicago and New York City was also found to be sinking at a rate of three millimeters per year. Researchers said about 34 million people—about 10 percent of the U.S. population—are in the subsidence zones. More than 29,000 buildings in the cities analyzed were found to be at very high risk of damage. Factors such as groundwater pumping and oil extraction are causing land to cave in on itself, which poses an infrastructure risk in major urban areas. Researchers noted that buildings can be 'silently' compromised over time, with damage only potentially noticeable when it is 'catastrophic. " 'Unlike flood-related subsidence hazards, where risks manifest only when high rates of subsidence lower the land elevation below a critical threshold, subsidence-induced infrastructure damage can occur even with minor changes in land motion,' the study's authors write. The study said that the extraction of groundwater is likely the cause of subsidence in Houston, the worst-impacted city. As cities continue to expand, populations increase, and climate change worsens, areas are likely to continue sinking. Droughts, for example, can dry out soil in cities like Houston, leading to further groundwater extraction, continuing the cycle. A separate 2023 study found that New York City is gradually sinking partly because of the weight of its skyscrapers. Meanwhile, Galveston, Texas, is experiencing rapidly rising sea levels, outpacing other coastal cities such as Miami, Florida, and Charleston, South Carolina. New Orleans, Louisiana, is rapidly subsiding at up to 50 millimeters per year. The coastal metropolis is built on soft, marshy land.
Gizmodo
09-05-2025
- Science
- Gizmodo
All 28 of the U.S.'s Largest Cities Are Sinking, Study Finds
America's biggest cities are slowly sinking—and not just the ones near the ocean, according to a study published today in the journal Nature Cities. The satellite-based study shows that all 28 U.S. cities with over 600,000 people are subsiding, putting infrastructure in fast-growing urban areas increasingly at risk. Researchers used satellite data to investigate the vertical land movements in large U.S. cities, finding that all of them are sinking to some extent. Groundwater extraction seems to be the most common culprit, and its impact on land movement has direct implications for the infrastructure in the country's most populated neighborhoods. 'As cities continue to grow, we will see more cities expand into subsiding regions,' Leonard Ohenhen, lead author of the study and a postdoctoral researcher at Columbia Climate School's Lamont-Doherty Earth Observatory, said in a university statement. 'Over time, this subsidence can produce stresses on infrastructure that will go past their safety limit.' Ohenhen and his colleagues used recent satellite data to map vertical land movement in the U.S.'s most populated cities, analyzing it in systematic 90-square-foot (28-square-meter) grids. While many people have heard that large coastal cities such as New Orleans are sinking, the study reveals that even municipalities far inland—including Denver, Oklahoma City, and Fort Worth—are subsiding. Overall, the results show that in 25 of the 28 cities analyzed, at least two-thirds of the land is sinking. Houston is the fastest sinking metropolis, with over 40% of its land dropping more than 0.20 inches (5 millimeters) every year—and 12% subsiding at twice that speed. Cities including New York, Las Vegas, Washington D.C., and San Francisco also have relatively small but fast-sinking zones. This contributes to differential motion: regions sinking at different speeds, or some regions subsiding while others uplift. This uneven movement can endanger infrastructure by causing buildings to tilt. While only around 1% of the documented areas are experiencing strong enough differential motion to impact infrastructure, these regions tend to be the most urbanized, accounting for around 29,000 buildings. According to the study, one in 45 buildings in San Antonio are at high risk, as are one in 71 in Austin, one in 143 in Fort Worth, and one in 167 in Memphis. An even more detailed study would be needed to assess the specific risk for individual buildings, Ohenhen said in the statement. 'Unlike flood-related subsidence hazards, where risks manifest only when high rates of subsidence lower the land elevation below a critical threshold, subsidence-induced infrastructure damage can occur even with minor changes in land motion,' the authors wrote in the study. Nevertheless, sinking land is generally more vulnerable to floods. By analyzing groundwater extraction alongside vertical land movements, the researchers determined that this activity is responsible for 80% of the documented subsiding. That's because when humans remove water from aquifers—layers of porous rock that hold groundwater—the pores can collapse, lowering the land surface above it. The researchers argue that this phenomenon will only worsen in some areas because of elements such as population growth (meaning increasing water needs) and climate-driven droughts. There are also other forces at play, however. Some sinking areas are still recovering from the bulging caused by long-gone ice age glaciers in North America's interior. The monumental weight of buildings might also impact some cities' land movement (cough cough, New York). Ultimately, the researchers hope their study will inspire a push for mitigation efforts, which could include land raising, building retrofitting, and updated construction codes. 'As opposed to just saying it's a problem, we can respond, address, mitigate, adapt,' Ohenhen concluded. 'We have to move to solutions.'
