MEXICO CITY — The NISAR satellite collected preliminary measurements of Mexico City's ground subsidence between October 2025 and January 2026, finding that some areas, including the city's main airport, are sinking by more than 2 centimeters per month. The data was gathered during the city's dry season by the joint mission of NASA and the Indian Space Research Organisation.

Operational since July 2025, NISAR tracks Mexico City's ground movement in real time using radar imaging. It is the first satellite to incorporate two synthetic aperture radars at different wavelengths, enabling it to monitor Earth's land and ice surfaces twice every 12 days.

"Nisar takes radar imaging observations of Earth to the next level. Nisar will see any change big or small that happens on Earth from week to week. No other imaging mission can claim this." said Marin Govorčin, a scientist at NASA's Jet Propulsion Laboratory.

On the NISAR subsidence map, areas with ground movement greater than 2 centimeters per month are marked in dark blue, while areas marked in yellow and red may correspond to background noise expected to diminish as the satellite collects more data. Benito Juárez International Airport operates within an area of accelerated ground subsidence. "Images like this confirm that the NISAR measurements are in line with expectations." said Craig Ferguson, deputy director of the NISAR project.

Mexico City has been sinking for more than a century, with the phenomenon first documented in 1925. The city and its surroundings were built on an ancient lake bed, making the underlying soil extremely soft. Groundwater pumping from the aquifer beneath the city exceeds natural recharge from precipitation, causing the aquifer to compact under the city's weight. The aquifer supplies about half of Mexico City's water, and its water table is contracting by about 40 centimeters per year.

Uneven settling occurs across distances as small as one meter, a phenomenon known as differential subsidence. According to NASA, small, uneven elevation changes over decades have fractured roads, buildings, and water lines. Many historic buildings in the central Zócalo plaza are visibly tilted, and the Angel of Independence monument on Paseo de la Reforma has had 14 steps added to its base as the surrounding land has gradually sunk.

"It affects the entire urban infrastructure of the city: the streets, the pipes for water distribution, the water supply, the drainage pipes." said Efraín Ovando Shelley, an engineer at the National Autonomous University of Mexico. The metropolitan area has about 22 million residents, with nearly 20 million people at risk from subsidence. "To stop the sinking, we would have to stop water extraction. And if we stop water extraction, what water are we going to drink? The standard joke is that if we can't drink water, well, let's drink tequila." Ovando Shelley said.