Mexico City Sinks Up to 2 cm per Month as NASA Satellite Captures Detailed Data
Oscar Lopez
Mexico City is sinking at an alarming rate, with some areas subsiding more than 2 cm per month, according to new satellite data from Nisar, the most powerful radar system ever launched into space. The phenomenon, driven by centuries of groundwater extraction, has caused historic buildings to tilt, infrastructure damage, and water loss. Experts warn that stopping the sinking would require halting water pumping, a move that would create a new crisis.
Walking into the vast Zócalo central square of Mexico City is a dizzying experience. At one end, the capital's towering cathedral leans one way. The adjacent Metropolitan Sanctuary tilts another. The nearby National Palace also appears crooked.
The sway of many historic buildings is the most visible sign of a phenomenon that has been underway for over a century: Mexico City is sinking at an alarming rate.
Now, the city's subsidence is being monitored in real time by one of the most powerful radar systems ever launched into space. Called Nisar, the satellite can detect minute changes on Earth's surface, even through dense vegetation or cloud cover.
According to scientists, images from Nisar have provided a clearer picture of the extent of subsidence and how it varies across different soil types than any previous space sensor. The system, a joint initiative between NASA and the Indian Space Research Organisation, detects that some areas of Mexico City, including the main airport, are sinking more than 2 cm each month.
Among the clearest examples of this rapid sinking is the Angel of Independence monument on the main Paseo de la Reforma avenue. Built in 1910 to mark the centennial of Mexico's independence, the 36-meter-tall monument has had 14 steps added to its base as the surrounding ground has gradually subsided.
The impact of subsidence can be seen throughout the metropolis of about 22 million people, from tilting buildings to warped roads and damage to the subway system. It affects all urban infrastructure: streets, water distribution pipes, water supply, and sewage systems.
First recorded in 1925, the city's sinking results from centuries of groundwater extraction. Because Mexico City and its surroundings were built on an ancient lakebed, the soil beneath the city is extremely soft. As water is pumped up from the aquifer below, the clay layer compresses, causing the city to sink quietly. The aquifer still supplies about half of the capital's water. As groundwater pumping increases, the aquifer contracts more, with water levels now dropping by about 40 cm per year.
This creates a vicious cycle: as the city sinks, old pipes carrying water through the urban center crack, causing the capital to lose an estimated 40% of its water to leaks. Combined with the climate crisis, which has brought years of low rainfall, the metropolis could plunge into a disaster scenario as taps in many areas run dry.
Efforts to address the city's slow sinking remain limited beyond reinforcing the foundations of old buildings. Experts say imagery from Nisar will help draw more attention to the problem, though actually stopping the subsidence is a challenging task. An engineer from the National Autonomous University of Mexico (Unam) emphasized: 'To stop the sinking, we must stop extracting water. And if we stop extracting water, what will we drink? The common joke is that if you can't drink water, then drink tequila.'
