A sinkhole opened up on a residential street on Chicago's South Side on Thursday morning, swallowing three cars and sending one person to the hospital.
According to the Chicago Tribune, the sinkhole opened up at about 5 a.m. on Houston St. in Chicago's South Deering neighborhood, where it quickly expanded from about 20 feet in diameter to about 40 feet. Two parked cars initially fell into the hole, and a third fell in as its driver was attempting to navigate around the hole and the ground below gave way. He was taken to Northwestern Memorial Hospital and is in "serious-to-critical" condition
According to the Associated Press, the sinkhole was preceded by a severe rainstorm that ruptured a water main in the neighborhood. The AP quotes a spokesman from the city's water department, who speculated that the weight of the rain-soaked ground could have cracked the cast-iron pipe, which was laid in 1915. Water from the pipe would have then quickly eroded the soluble rock.
"The water will come out any way it can," the spokesman told the AP.
Sinkholes are often caused by the underground erosion of salt beds or soluble sedimentary rocks, such as limestone or dolomite. Groundwater flows through these rocks, creating subterranean caverns that can suddenly collapse.