It’s happening faster and faster. Mexico City is sinking at great speed. More or less, between 20 and 30 centimeters per year on average. Subsidence is not homogeneous. Iztapalapa, Tláhuac and Xochimilco, in the southeast, are the most affected areas. It is made worse by the drilling of wells and excessive water extraction.
Sergio Raúl Rodríguez Elizarrarás is a researcher at UNAM’s Institute of Geology. He explains that between 1920 and 1930, the authorities started drilling wells. However, this has caused the subsoil to become unbalanced.
Sediments are lost
“Mexico City is historically developed on Lake Texcoco. Urbanization continues to grow exponentially. This needs drinking water. And it is extracted from the subsoil. The external sources from which the city is supplied are no longer sufficient,” he says. The digging of wells increases more and more.
“The subsoil is decompensated and, with this, what is called subsidence. The sediments on which the city is settled lose spaces. Urban development generates settlement and general subsidence,” he said.
An emblematic example is the centennial monument called the Angel of Independence. Its construction began in 1900. In 1906, one of the sides of the monument began to sink. It was then necessary to demolish what had been built and design new foundations. Eventually, 14 more steps were added to protect the structure.
The reason? The pumping of water in deep wells. But in the central part of the city there are other examples. The Palace of Fine Arts or the Metropolitan Cathedral. For this reason, from the 40’s and 50’s the wells were taken to the periphery. Iztapalapa, Xochimilco, Tláhuac and some parts of the municipality of Chalco. Thus they moved the same problem elsewhere.
There are sites that are already sinking almost two meters every ten years. Mexico is sinking at great speed. Rodríguez Elizarrarás urges to regulate urban growth and land use planning.
“We want the impacts to be considerably less. We have to take into account regularization and zoning studies. Areas that are no longer suitable for urban growth should be limited,” he said.