And we have no way to detect them.

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Sinkhole Swallows Sleeping Man In Florida
-There's a terrifying story from Florida this morning.

Sinkhole, Landslides Wreak Havoc in Guatemala: Big Pics
-In downtown Guatemala City, the rains opened an enormous sinkhole 66 feet across and 100 feet deep on Saturday that swallowed a clothing factory and a city intersection.

Brother Tries to Save Man After Massive Sinkhole Swallows Florida Bedroom
-A Florida man screamed for help and disappeared as a large sinkhole opened under the bedroom of a house, his brother said Friday.