The Wild File: Sinkholes

Guatemala Sinkhole     Photo: Courtesy of horslips5 on Flickr.

Q. What are the odds that my house will fall into a sinkhole like the one that formed in Guatemala?

A. Not likely, but sinkholes are becoming more common. In May, when photos of the Guatemala City sinkhole—which consumed an entire three-story building—first surfaced on the Web, a chorus of skeptics cried Photoshop. Indeed, the cavity was a nearly perfect circle, 60 feet in diameter and 100 feet deep. As sinkholes go, though, this one was an anomaly. It formed in volcanic pumice rather than softer mineral rock like limestone or gypsum. Normally, sinkholes are primed by years of acidic rainwater dissolving minerals in the soil or bedrock, creating an area of porous latticework that collapses suddenly when the column is disturbed. While the Guatemala hole's implosion was most likely activated by a deluge from Tropical Storm Agatha, the real culprit was an outdated sewage system that sped up the erosion process. "Increases in urban development, leaky infrastructure, and groundwater withdrawals all contributed," says USGS hydrogeologist Patricia Metz.

As for your chances of getting that ol' sinking feeling in the U.S., be aware that parts of Texas and the Great Lakes region are prone to sinkholes, but the most vulnerable spots are in northern and west-central Florida.

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