Heat down below is making the ground shift under Chicago

[Collection]Since the mid-20th century, the ground between the city surface and the bedrock has warmed by 5.6 degrees Fahrenheit on average, according to a new study out of Northwestern University. All that heat, which comes mostly from basements and other underground structures, has caused the layers of sand, clay and rock beneath some buildings to subside or swell by several millimeters over the decades, enough to worsen cracks and defects in walls and foundations.