The largest city in North America is sinking into the ground by tens of centimeters every year
The capital of Mexico is sinking, and a powerful new satellite that monitors changes in the ground level around the globe has discovered how fast this process is, which can reach 35.5 centimeters per year, the Space.com site reports on Wednesday, quoted by Agerpres.
The NISAR (NASA-ISRO Synthetic Aperture Radar) satellite, launched on July 30, 2025 as part of a partnership between NASA and the Indian Space Research Organization (ISRO), has the mission of monitoring in real time the changes produced on the Earth's surface, from the sinking of some lands and the retreat of glaciers, to the movement of tectonic plates and the spread of wildfires.
NISAR does all this with astonishing precision, with a margin of error of less than 1 cm.
“The sinking process of Ciudad de Mexico is well-known, and such images are just the beginning for NISAR,” said David Bekaert of the Flemish Institute for Technological Research in Belgium and a member of the NISAR research team.
Why is Mexico's capital sinking into the sea?
It has been known since 1925 that much of the city of 9.2 million people is sinking at a rate of up to 35.5 centimeters per year.
The capital of Mexico is the largest city in North America, with a population greater than that of New York, home to 8.3 million inhabitants.
This sinking is related to the fact that the city is built on top of an aquifer, or an underground layer of permeable rock and sand, left behind by a dried-up ancient lake bed – and the resulting groundwater pumping and the weight of urban sprawl compresses these sedimentary layers.
The result is damage to buildings and infrastructure, such as Mexico City's subway system.
A new discovery made from space
“NISAR's L-band longwave radar will make it possible to detect and monitor land subsidence in more difficult and densely vegetated regions, such as coastal communities, where they can have the amplified effect of both land subsidence and sea level rise,” said Craig Ferguson, NISAR deputy director at NASA Headquarters in Washington, DC
NISAR is one of the most powerful radars ever launched into space. L-band refers to the microwave frequency of 1-2 gigahertz (GHz), but the satellite also carries an S-band radar that operates at higher frequencies of 2-4 GHz. NASA built the L-band radar, sensitive to changes in bedrock and ice, which was used in this study of Mexico City, while ISRO built the S-band radar, sensitive to changes in vegetation.
“We will see an influx of new discoveries from around the world, given NISAR's unique detection capabilities and its constant global coverage,” Bekaert said.
The radar image of Ciudad de Mexico looks like a contradictory patch of blue and yellow paint. These colors are false, designed to highlight soil changes. Dark blue represents parts of the city that sank by more than 2 cm between October 2025 and January 2026, which is Mexico's dry season. Yellow and green areas represent residual noise. It is expected to decrease as NISAR passes more over Mexico and the signal-to-noise ratio improves.
“Images like this confirm that the NISAR measurements line up with expectations,” Ferguson pointed out.
PHOTO article: Lunamarina / Dreamstime.com.
