Photo: Daniel LeClair, Reuters
Update: Additional photos can be found here.
According to an AP article available here (AOL) and here (Washington Post), local residents had been hearing noises and feeling tremors for a month prior to the collapse. Officials have cited recent rains and broken sewer mains probable causes of the collapse. The article doesn’t mention anything about the geology of the area, but the obvious conclusion would be limestone/dolomite rock and subsequent karst landforms. If any additional information on this collapse comes up, let me know. Thanks for the heads-up Juan.