Mexico City has been slowly sinking for more than a century. Now, a satellite is confirming it with millimeter-level precision and near real-time data.
Between October 2025 and January 2026, some areas of the Mexican capital dropped more than three-quarters of an inch per month. That finding came from the NISAR satellite, developed jointly by NASA and the Indian space agency ISRO and launched on July 30, 2025, from the Satish Dhawan Space Centre in India.
NASA published the findings this week.
The map generated by NISAR uses color gradients to show the extent of the problem. Dark blue zones mark areas where the ground is dropping more than three-quarters of an inch per month. The worst-affected zones appear primarily around the artificial lake Nabor Carrillo, northeast of the airport, and across the ancient lakebed system of Lake Chalco.
NISAR has brought new precision to the study of a problem that scientists have long recognized.
One of the defining features of the NISAR satellite is its dual-radar system, capable of penetrating clouds and vegetation to detect millimeter-scale changes in the ground. With an antenna spanning nearly 40 feet, it scans the Earth every 12 days, generating a continuous record of surface deformation.
NASA chose Mexico City as a test case precisely because the phenomenon was already well-documented. Craig Ferguson, NISAR’s deputy project manager at NASA, noted that “images like this confirm that NISAR’s measurements align with expectations.” By cross-referencing the satellite data with earlier studies, the agency was also able to verify the accuracy of its own instruments.
David Bekaert, project manager at the Flemish Institute for Technological Research and a member of NISAR’s science team, warned that “Mexico City is a well-known hotspot when it comes to subsidence” and predicted that the data still to come would be even more revealing.
The City Built on a Lake
What, then, is causing it?
The roots of the problem reach back to 1325, when the Mexica founded Tenochtitlan on an island in the middle of Lake Texcoco. After the Spanish conquest, colonial authorities drained much of the lake, dismantled the Albarradon de Nezahualcoyotl, and diverted rivers like the Rio de la Piedad into underground channels.
Homes and housing developments sprang up on the drained lakebed as the city spread across it. But the weight of urban development compressed the ancient lake-floor sediments, causing the ground to slowly subside.
A second factor compounds the first: Mexico City draws far more water from underground than natural processes can replenish.
According to UNAM, the city’s aquifers are naturally replenished by roughly 25 billion cubic feet of water per year, but nearly 46 billion cubic feet are extracted annually. Some 71% of the city’s water supply comes from those underground sources.
When groundwater is depleted, the sediments lose the support holding them in place and compact under their own weight. Inevitably, the surface drops.
The most affected areas include the boroughs of Iztapalapa, Gustavo A. Madero, Tlahuac, Venustiano Carranza, and Iztacalco.
In parts of Iztapalapa, subsidence rates of up to 15 inches per year have been recorded. In Gustavo A. Madero, the rate reaches roughly 12.5 inches annually. Around the former Lake Texcoco — including Nezahualcoyotl, Chalco, and Ecatepec — recorded rates range from 17.5 to nearly 20 inches per year.
UNESCO-supported research indicates that more than 457,000 properties and approximately 1.5 million people live in areas classified as at high or very high risk from surface faulting — which manifests as cracks in the ground, structural damage to homes, and broken pavement.
Perhaps no monument illustrates the problem more vividly than the Angel of Independence. Unveiled in 1910 along the Paseo de la Reforma, it now stands on 14 steps that were added to its base as the surrounding ground sank. The roughly 98-foot column is effectively taller today than when it was built — the earth around it has sunk nearly 33 feet in a century.
A similar relocation, though on a citywide scale, is what Kiruna, in the Swedish Arctic, is experiencing today.
What NISAR Can Do Now
Ferguson explained that NISAR’s L-band radar “will enable the detection and monitoring of land subsidence in more complex, densely vegetated regions, such as coastal communities, where the combined effects of subsidence and sea-level rise may occur together.”
Subsidence cannot be reversed, but its consequences can be managed. Reducing dependence on aquifers, developing alternative water sources, and promoting groundwater recharge will not undo the damage already done — but they could slow the process and, more importantly, offer a viable path forward for a megacity of more than 20 million people.
Mexico City is not alone in this. Tokyo and Shanghai faced the same problem in the twentieth century and managed to bring it under control through improved water management policies. The NISAR map, for now, lays bare the scale of the problem. What comes next depends on decisions that no satellite can make.
