The Angel of Independence Has 14 Steps. Here Is Why.
Mexico City is sinking. The ground is disappearing from beneath one of the world's largest cities, and it has been happening so long that the Angel of Independence — the 114-foot monument erected in 1910 to commemorate a century of Mexican independence — now sits 14 steps higher than it was built. Not because the monument rose, but because the city around it dropped. NASA
That is the most concrete fact in a new analysis from the NISAR satellite, a joint NASA-ISRO spacecraft launched last July that maps Earth's surface with a 39-foot radar reflector — the largest antenna NASA has ever put in orbit. NISAR passed over Mexico City between October 2025 and January 2026 and found parts of the metropolitan area sinking at nearly 10 inches per year, with some zones dropping at a rate of 0.78 inches per month. Over the last century, the city has settled more than 39 feet. Parts of it in the 1990s and 2000s were dropping at 14 inches annually. AP News
"I have one of the fastest velocities of land subsidence in the whole world," said Enrique Cabral, a geophysics researcher at the National Autonomous University of Mexico. The damage is not hypothetical. "It damages part of the critical infrastructure of Mexico City, such as the subway, the drainage system, the water, the potable water system, housing and streets." AP News
The cause is basic physics and a century of decisions. Mexico City was built on an ancient lake bed. Extract groundwater faster than the aquifer replenishes, and the clay beneath the city compresses. The weight of urban development accelerates the compaction. The city has been sinking since an engineer first documented the problem in 1925. Benito Juarez International Airport — Mexico City's primary hub — appears in NISAR's data, visibly dropping. NASA
NISAR's contribution is precision and scale. The satellite uses L-band and S-band synthetic aperture radar to track ground deformation day or night, through clouds, twice every 12 days. The 12-day revisit cadence means changes that used to take months or years of ground surveys to detect can now be spotted in near-real-time. Craig Ferguson, deputy project manager at NASA Headquarters, said the Mexico City results confirm that NISAR's measurements align with expectations — and that the satellite will now extend this kind of mapping to places where ground-based monitoring has never reached. NASA
David Bekaert, a NISAR science team member from the Flemish Institute for Technological Research, put it plainly: "Mexico City is a well-known hot spot when it comes to subsidence, and images like this are just the beginning for NISAR." The longer wavelength L-band radar can track land sinking and rising, glaciers sliding, and croplands growing in densely vegetated coastal regions where subsidence compounds sea level rise — areas where older satellites simply could not see clearly. NASA
The Angel of Independence was not built with 14 steps. It was erected on a flat base. As the ground sank, the city added steps to keep the monument accessible — a running tally of geological subsidence recorded in stone and mortar, one step at a time, for 116 years.
The satellite sees what the steps have been saying all along.