NASA satellite reveals Mexico City sinking at alarming rate

Mexico City is sinking, and a NASA satellite has now put a precise number on just how fast. The city, built on a former lakebed, has been slowly settling for decades. But new data from the space agency's satellite-based radar system reveals that parts of the metropolis are dropping at a rate of up to 50 centimeters per year.

The findings, published by researchers using NASA's ISRO Synthetic Aperture Radar (NISAR) mission, offer the most detailed picture yet of the subsidence crisis. The satellite measures ground deformation with millimeter-level accuracy, allowing scientists to map the sinking across the entire city.

Why Mexico City is sinking

The cause is groundwater extraction. Mexico City sits on a thick layer of clay, which compresses when water is pumped out. For over a century, the city has relied on this aquifer to meet its water needs, and the land has been sinking ever since.

In some neighborhoods, the subsidence is so rapid that sidewalks crack, buildings tilt, and water and sewage pipes break. The damage is not just cosmetic. It threatens the structural integrity of thousands of buildings and adds to the city's already strained infrastructure costs.

The NISAR data shows that the sinking is not uniform. Some areas, particularly those with heavy groundwater pumping, are dropping far faster than others. The most affected zones are in the eastern parts of the city, where the clay layer is thickest.

What the satellite found

NASA's satellite uses a technique called interferometric synthetic aperture radar (InSAR). It sends radar waves to the ground and measures the signal that bounces back. By comparing images taken at different times, scientists can detect minute changes in the Earth's surface height.

The new measurements reveal that the average sinking rate across Mexico City is around 30 centimeters per year. But in some hotspots, the rate exceeds 50 centimeters. That means in a decade, parts of the city could be five meters lower than they are today.

The data also shows that the sinking is accelerating in some areas. This is likely because groundwater extraction is increasing as the city's population grows and its water system struggles to keep up.

The bigger picture

Mexico City is not alone. Many cities around the world, from Jakarta to Venice, are sinking due to groundwater extraction. But few are sinking as fast as Mexico City, and few have as many people living on top of the problem.

The city's subsidence has been known for decades. But the NISAR satellite now provides a tool to monitor it in near real time. This could help authorities identify the worst-affected areas and target efforts to reduce groundwater pumping.

Already, some parts of the city have seen slower sinking rates after water management reforms were implemented. But the scale of the problem remains enormous. The city loses an estimated 40% of its water to leaks, meaning more water has to be pumped from the ground to make up for the loss.

Officials have not yet commented on the latest NASA findings. But the data is clear: the ground under Mexico City is dropping, and the pace is picking up. Without major changes in how the city manages its water, the sinking will continue.

What happens next depends on whether the city can find alternative water sources and fix its leaking pipes. The satellite data will help track progress. But for now, the ground keeps moving.