Satellite study maps sinking ground across 465 major cities worldwide
A Nature Cities assessment compares ground movement in large cities over 2014–2023. It finds regional hotspots and changing trends, while leaving causes and future damage unresolved.
Nature Cities published a satellite assessment on 12 October 2026 mapping ground movement across 465 cities worldwide with populations above one million. The study finds widespread sinking, with the most severe regional patterns in Southeast Asia, West-Central Asia and North America. Its consistent method gives city planners a way to compare measured movement, but the maps do not establish what damage will occur or how long current trends will continue.
Researchers led by Wang, Ao and Tao analysed satellite radar observations from 2014 through 2023. They produced detailed maps of land movement and estimated how rates changed over that period. The principal measure is relative local subsidence: it describes movement within the areas studied and should not be read as an absolute measure of how far every city has dropped.
Where the satellite maps show the strongest sinking
The study identifies pronounced regional patterns in Southeast Asia, West-Central Asia and North America. It also records subsidence in regions the authors describe as less studied, including South America, Africa and Russia. Those findings broaden the geographical picture, but a regional hotspot does not mean every part of every city in that region is sinking at the same rate.
Phys.org reports that a localized part of Mexico City sank at about 217 millimetres a year, while the median across the city was 8 millimetres a year. The difference matters: a rate measured in one part of a city cannot describe conditions across the whole city. The report gives citywide median rates of about 33 millimetres a year for Medan, 22 for Bandung and 11 for Isfahan.
Other places in the assessment were much closer to stability on the annual measure reported by Phys.org. Boston, New York, London, Beijing, Tokyo, Seoul, Sydney, Montevideo and Naples had estimated movement ranging from 0.1 to 1.9 millimetres a year, either sinking or rising. Phys.org cautions that values this small need careful interpretation. A near-stable citywide estimate also says little about any smaller area within a city.
Which cities are slowing down or sinking faster?
The researchers found marked slowing of subsidence across many cities in Southeast and East Asia. Yet substantial urban areas in those same regions still showed accelerating subsidence. The study therefore presents a mixed picture: a slowing trend in one place does not establish that sinking has stopped there, and it does not describe the trajectory of nearby areas. Continued measurements will be needed to see whether the estimated changes persist.
Land subsidence can damage buildings, foundations, drainage and sewage systems, and it may increase flood risk, Phys.org explains. These are reasons to monitor ground movement, not a tally of damage caused in the 465 cities. Neither a high measured rate nor a change in that rate, by itself, identifies the cause at a particular site or shows that a particular response has already reduced risk.
How the 465-city study extends earlier research
The authors say earlier global assessments were difficult to compare because they used different methods or periods, or examined only a small number of cities. Their 465-city analysis applies a consistent satellite-based approach over the same 2014–2023 period. That makes comparisons more useful, although the study still measures places with differing local conditions and does not turn those measurements into a forecast of future losses.
An earlier study published in Science assessed subsidence in 82 major Chinese cities. Ao is associated with both that work and the new Nature Cities paper. The China assessment is a precedent for studying urban sinking at scale; it does not independently confirm the new global results. The broader survey adds cities across multiple regions to the research record.
What the measurements cannot yet establish
The Nature Cities authors describe their main results as relative local movement. They also compare them with estimates aligned to a global vertical land-motion product, but say that correction introduces uncertainty. Phys.org notes two further limits: areas beyond city administrative boundaries may be omitted, and uncertainty is greater where ground-station coverage is sparse. These qualifications matter when a reader compares a small estimated movement with a much larger local hotspot.
The authors make the underlying Sentinel-1 radar imagery and city-level movement and uncertainty data accessible through a Global Urban Subsidence visualization and a dataset repository. They say continued monitoring could test whether current trends hold and help direct attention to affected areas. The published measurements establish a comparison baseline; they do not show that any city has adopted a particular intervention or that future damage has been prevented.
Sources and context
- A global view of urban land subsidence and its changing trajectoriesNature Cities / Springer Nature
- Major cities worldwide are sinking, satellite data revealPhys.org (Nature Publishing Group / Science X)
- A national-scale assessment of land subsidence in China’s major citiesScience
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