Satellites show 28 US cities are sinking, including NYC and Chicago

A new study has found that the 28 most populous cities in the United States — including New York, Chicago, Dallas and Denver — are sinking at rates between two and 10 millimeters (0.08 and 0.4 inches) per year.

Using satellite-based radar measurements, a team of researchers from Virginia Polytechnic Institute and State University developed high-resolution maps of sinking land, or subsidence, across major U.S. cities. In each of the 28 cities studied, at least 20% of the city was sinking; in 25 of the cities, at least 65% of the land was sinking.

Cities across Texas show the greatest rates of subsidence, with Houston taking the lead. There, some 40% of the city is sinking at more than 5 millimeters (0.2 inches) per year, while 12% of the city is sinking at 10 millimeters (0.4 inches) per year.

Land subsidence isn't uncommon around the world, with many areas subsiding due to natural geological processes. However, the Virginia Tech team concluded that 80% of urban subsidence in the U.S. is caused by groundwater removal for human use. And, as cities grow, this problem may be further exacerbated.