What Do You Do With a Gargantuan Sinkhole?

For a small sinkhole in your yard, experts recommend dropping solid material to the bottom and filling it with soil. For a giant sinkhole in your city, experts are flummoxed. Geologists aren't sure why a mammoth sinkhole that ate a three-story building opened up in downtown Guatemala City, and they warn that simply filling the hole won't do any good unless they can get to the bottom of what caused it, the Christian Science Monitor reports.

Some geologists believe there must have been an ancient underground cavity that collapsed. Others, noting that another sinkhole opened up nearby in 2007, believe it was caused by government neglect of the sewer system. An expert who investigated the earlier sinkhole tells National Geographic that the sinkhole isn't a true sinkhole at all, but a man-made "piping feature," and warns that more are likely to appear unless the Guatemalan government inspects the sewer system for weaknesses. (More Guatemala sinkhole stories.)