Why is Mexico City Sinking?

Written by Jedediah Watkins 

Read Time: 10 minutes

In the heart of Mexico, amidst the vibrant culture, rich history, and bustling streets, lies a phenomenon that has captivated the world's attention—the sinking of Mexico City. When I first visited Palacio De Bellas Artes, I discovered that every year it sinks by roughly 10 cm (which is WILD). In my search for answers I unravelled not only is Palacio De Bellas Artes sinking, but with it is the rest of the city. Join me on a journey of discovery as we unravel the geological mysteries, historical narratives, and environmental challenges that contribute to this intriguing phenomenon.

The Ground Beneath Mexico City: A Fragile Foundation

At the core of Mexico City's sinking lies its geological composition—a delicate balance of soil, sediment, and ancient lake beds. The city was originally built on the dried-up lakebed of Lake Texcoco, a vast body of water that once covered a significant portion of the Valley of Mexico.

The soil in this region is predominantly clay-like, known as lacustrine clay, which is highly susceptible to compaction and subsidence. As the city grew and urbanization intensified, the weight of buildings, infrastructure, and population exerted immense pressure on the underlying soil layers, leading to gradual sinking and settlement. With the masses of people quickly moving into this incredible city, the infrastructure had to grow to keep up with the rapid growth in demand. Building schools, train stations, libraries and other heavy structures that weigh down this soft ground.

As the population grew, so did the need for water. Adding to the complexity is the presence of underground aquifers that have been overexploited for centuries, causing further subsidence as water is extracted from beneath the city. These combined factors create a perfect storm for land subsidence, a process where the ground gradually sinks and settles over time. Deforestation has also added to the problem, removing spring water and underground support for the land.

The use of wells in the early 19^th century drew water out of the land the city was built on, leaving extra room for the ground to sink and destabilise. During the 50’s and 60’s the city sank so deep it dipped two metres below Lake Texcoco creating a major risk of flooding. In response engineers built wells into the lake to suck water out, dropping water levels below that of the city center.

Who Came Before: Tracing Mexico City's Indigenous Roots

Before the Spanish conquistadors arrived and founded Mexico City in 1521, the region was inhabited by several indigenous civilizations, most notably the Aztecs (or Mexica). The Aztecs established their capital city of Tenochtitlan on the marshy islands of Lake Texcoco, where Mexico City now stands.

The ingenious Aztec engineering marvels, including chinampas (floating gardens) and causeways, allowed them to thrive in a challenging environment characterized by seasonal flooding and marshy terrain. They built a complex society, complete with temples, palaces, markets, and a sophisticated agricultural system. As we have found time and time again, indigenous populations have utilised the space and land they occupy, instead of endearing to change it to the needs of the people.

The Aztecs, with great knowledge of the land became masters of engineering and resource management. They harnessed the waters of Lake Texcoco to fuel their civilization's growth. They constructed intricate systems of canals and aqueducts that crisscrossed the lake's surface, allowing for efficient transportation of goods, water distribution for agriculture, and navigation for trade. The chinampas, or "floating gardens," were perhaps their most renowned innovation, consisting of fertile plots of land built on rafts of vegetation and soil anchored to the lakebed. These floating gardens not only provided sustenance through agriculture but also served as a natural filtration system, purifying the lake water and enhancing its quality for consumption. The Aztecs' symbiotic relationship with Lake Texcoco exemplified their deep understanding of ecological principles and their ability to thrive in harmony with their environment.

The arrival of the Spanish marked a pivotal moment in the region's history, leading to the eventual conquest of the Aztec Empire and the establishment of colonial rule. The Spanish built Mexico City atop the land of Tenochtitlan, incorporating elements of indigenous architecture and urban planning into their new capital. All the while bringing more people in than had ever been there before.

The Altitude Factor: Mexico City's High-Elevation Challenge

One of the defining features of Mexico City is its high elevation, situated at an average altitude of around 2,240 meters (7,350 feet) above sea level. This elevated location poses unique challenges and impacts on the city's infrastructure, environment, and inhabitants.

The altitude contributes to cooler temperatures and thinner air, which can affect visitors and residents, especially those not accustomed to high elevations. It also influences weather patterns, with distinct seasons characterized by rainy summers (wet season) and drier winters (dry season).

For Mexico City, the altitude exacerbates the sinking phenomenon. As the city sinks, it experiences uneven subsidence, leading to infrastructure damage, water management challenges, and increased vulnerability to flooding during the rainy season.

The Toll of Time: Coping with Mexico City's Sinking Reality

Over the centuries, Mexico City has grappled with the consequences of its sinking ground. Buildings tilt, streets crack, and infrastructure strains under the pressure of subsidence. Efforts to mitigate the sinking include groundwater management, land-use regulations, and structural reinforcements. Burst pipes and broken flooring are regular occurrences in some of the larger buildings in the city centre where the sinking has taken a larger effect.

In recent years, innovative solutions have emerged, such as the use of GPS technology to monitor ground movements, implementation of sustainable drainage systems, and reforestation projects to enhance soil stability. These initiatives reflect a concerted effort to address the environmental, social, and economic impacts of land subsidence.

Despite the challenges, Mexico City continues to thrive as a vibrant cultural hub, attracting visitors from around the world with its historical sites, culinary delights, and artistic offerings. Its sinking ground serves as a reminder of the interconnectedness between human activities, natural processes, and the resilience of urban landscapes. There is also potential to look back on the indigenous answers to these challenges and to integrate them into contemporary methods for this city wide issue.

As we delve into the depths of Mexico City's sinking reality, we gain a deeper appreciation for the complexities of urbanization, history, and environmental stewardship. It's a city where the past and present converge, where the ground beneath our feet tells a story of adaptation and ongoing exploration. Mexico City may sink, but its spirit remains buoyant, drawing strength from its diverse heritage and unwavering resolve to navigate the challenges of an ever-growing dynamic world.

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