Mexico City is sinking.
The city is built on the remains of an ancient Aztec island city, and as the 21 million citizens use the water beneath, the ground sinks.
Layers of soft clay under the city vary in thickness and the ground sinks faster where clay dries out, causing buildings to tilt, sidewalks to collapse and more.
Experts say parts of the metropolitan area have sunk by as much as 27 feet since the late 19th century. Some of the heaviest stone buildings, such as the opulent Palace of Fine Arts, have sunk 13 feet in a century.
Around 50 buildings have been condemned since 2006 and 5,000 more are at risk.
Oscar Alejandro Roa, director of prevention at the city’s Civil Defense Bureaus says, “You have a permanent feeling of vertigo.”?
Adding to the danger: Earthquakes are a constant threat with temblors striking the area on a regular basis. An 8.1 quake struck the city in 1985, killing over 10,000.