A new study of the 28 most populous U.S. cities finds that all are sinking to one degree or another. The cities include not just those on the coasts, where relative sea level is a concern, but many in the interior. Furthermore, using newly granular data, the study finds that some cities are sinking at different rates in different spots, or sinking in some places and rising in others, potentially introducing stresses that could affect buildings and other infrastructure. Massive ongoing groundwater extraction is the most common cause of these land movements, say the authors, though other forces are at work in some places.

Rapidly subsiding coastal metropolises such as Jakarta, Venice and New Orleans have already drawn major attention, and multiple recent studies have shown that many places along the U.S. East Coast and elsewhere are subsiding. But most studies have relied on relatively sparse data spread over wide areas to paint a broad picture.

Looking at all U.S. cities with populations exceeding 600,000, the new study uses recent satellite data to map out vertical land movements down to the millimeter in grids measuring just 28 meters (about 90 feet) square. The authors found that in 25 of the 28 cities, two-thirds or more of their area is sinking. Overall, about 34 million people live in affected areas.

The fastest-sinking city is Houston, with more than 40% of its area subsiding more than 5 millimeters (about 1/5 inch) per year, and 12% sinking at twice that rate. Some localized spots are going down as much as 5 centimeters (2 inches) per year. Two other Texas cities, Fort Worth and Dallas, are not far behind. Some localized fast-sinking zones in other places include areas around New York's LaGuardia Airport, and parts of Las Vegas, Washington, D.C. and San Francisco.