Sinkholes

A gaping sinkhole opened in the bottom of a pool at the home of Brad Thelen in Erwin, Tenn., on the evening of Wednesday, Dec. 7, 2011, draining the family's swimming pool. By the next day, it had tripled in size and was not far from the Thelans' home. The family removed valuables and was staying with relatives until the sinkhole stabilized.

Credit: Tony Duncan/Johnson City Press/AP