Walking into Mexico City’s sprawling central Zócalo is a mesmerizing experience. At one end of the plaza stands the grand cathedral, its imposing spires leaning in one direction, while the adjacent Metropolitan Sanctuary tilts in the opposite direction. The nearby National Palace also appears skewed. This dramatic display hints at a more unsettling reality: Mexico City is gradually sinking.
This alarming phenomenon has been occurring for over a century, and its progress is now monitored with precision by Nisar, one of the most advanced radar systems ever launched into space. This satellite is capable of detecting minute variations in Earth’s surface, even through dense foliage or cloud cover.
“Nisar takes radar imaging observations of Earth to the next level,” explained Marin Govorčin, a scientist at NASA’s Jet Propulsion Laboratory. “Nisar will observe any change, big or small, that occurs on Earth from week to week. No other imaging initiative can make this claim.”
Though this isn’t the first time that Mexico City’s subsidence has been observed from space, the Nisar mission provides unprecedented insight into the expansiveness of this sinking and how it varies across diverse landscapes. It has also penetrated previously difficult-to-study areas on the city’s outskirts, owing to their complex terrain.
The ramifications of this imagery extend well beyond the borders of the Mexican capital. “This study of Mexico City highlights the potential applications of the Nisar system,” commented Darío Solano-Rojas, an engineer at the National Autonomous University of Mexico (UNAM). “It’s valuable not just for understanding sinking cities, but also for studying volcanoes, earthquake-related deformations, and landslides.”
According to NASA, this advanced technology also assesses various issues related to the climate crisis, such as glacier movement, agricultural efficiency, soil moisture, forestry health, and coastal flooding.
“Images like this are just the start,” remarked David Bekaert, a project manager at the Flemish Institute for Technological Research and a member of the Nisar science team. “We are poised to witness a surge of new discoveries globally.”
The Nisar system, a collaboration between NASA and the Indian Space Research Organisation, revealed that some regions of Mexico City, including its main airport, are sinking at rates exceeding 2 cm per month—among the fastest globally.
A striking illustration of this rapid sinking is the Angel of Independence statue located on the city’s main Paseo de la Reforma avenue. Erected in 1910 to celebrate 100 years of Mexican independence, the 36-meter monument has had 14 steps added to its base as the ground around it has gradually subsided.
The subsidence’s impact is evident throughout the metropolis, home to approximately 22 million residents, resulting in tilting structures, warped roads, and damage to the underground metro system.
Efraín Ovando Shelley, another engineer at UNAM, stated: “It affects the entire urban infrastructure of the city: from the streets to the water distribution pipes and water supply, to the drainage systems.”
First documented in 1925, the sinking of the city is primarily due to centuries of groundwater exploitation. As Mexico City and its surroundings were constructed on an ancient lake bed, the soil beneath is remarkably soft. When water is extracted from the aquifer below, this clay-like earth compresses, causing the city to gradually sink.
Govorčin added: “Mexico City is subsiding mainly because groundwater is being extracted from the aquifer beneath at a rate that significantly surpasses the natural replenishment from precipitation. As water is removed, the aquifer compresses under the weight of the city above.”
The underground aquifer still contributes approximately half of the capital’s water supply. However, as the pumping of groundwater has escalated, the shrinking of the aquifer has intensified, leading to the water table contracting by around 40 cm each year.
This creates a destructive cycle: as the city sinks, the aging pipes responsible for delivering water across the urban center become cracked and broken, resulting in an estimated 40% of the water supply being lost due to leakage. Compounding this issue are the effects of climate change, which have triggered prolonged periods of low rainfall, pushing the metropolis towards a potential crisis where taps in large areas may run dry.
As for addressing the gradual sinking, efforts have been limited primarily to strengthening the foundations of historical structures. Experts believe that Nisar imagery will enhance awareness of the issue, yet halting the sinking itself remains a formidable challenge.
“To stop the sinking, we would need to cease water extraction,” noted Shelley. “But if we halt extraction, where will we source our drinking water? The standard joke is that if we can’t drink water, we might as well drink tequila.”
Key Takeaways
- Mexico City is sinking at a significant rate due to groundwater extraction.
- The Nisar satellite provides advanced monitoring of subsidence in real-time.
- This sinking affects urban infrastructure, including roads and water supply systems.
- Historical landmarks like the Angel of Independence illustrate the subsidence issue.
- The aquifer’s depletion is exacerbated by climate change and infrastructure challenges.
FAQ
What is causing Mexico City to sink?
The sinking is primarily due to excessive groundwater extraction from the aquifer beneath the city’s ancient lakebed.
How fast is the city sinking?
Some areas, including the main airport, are sinking by more than 2 cm per month, one of the fastest rates in the world.
What are the risks associated with this subsidence?
The sinking can lead to infrastructure damage, such as cracked roads and broken water pipes, which can cause significant water loss and affect daily life.
In conclusion, Mexico City’s slow descent presents a complex issue that intertwines urban planning, resource management, and environmental concerns. Addressing this challenge will require innovative solutions and collective action to secure the city’s future.
