NEW YORK, May 8 (Xinhua) -- The land underneath the largest cities in the United States is sinking, a phenomenon threatening buildings, roads and rail lines, but that sinking, known as subsidence, is not happening in the same way in each place, or even the same way across one city, according to new research.
Researchers mapped out how land is moving vertically across the 28 most populous U.S. cities and found all the cities were compressing like a deflated air mattress. Twenty-five of them are dropping across two-thirds of their land. About 34 million people, about 10 percent of the U.S. population, live in the subsiding areas, according to the study published on Thursday in Nature Cities.
The cities with the most widespread declining, where 98 percent of the city's area was affected, include: Chicago; Dallas; Columbus, Ohio; Detroit; New York; Indianapolis; Charlotte; Denver; Houston; and Fort Worth.
Many of these sinking cities are located in the country's interior. Subsidence has typically been a high concern in coastal cities, where rising sea levels can more easily come ashore and inundate areas. But the researchers say sinking land inland can destabilize infrastructure as well as worsen flooding during storms. ■