• Credit: USA Today

Florida's porous limestone geology claimed two more victims last week as a 50-foot sinkhole opened up in a Dunedin, Florida, neighborhood. Awakened at night by a loud sound, the family first feared an intruder, homeowner Michael Dupre told a reporter: "I grabbed a rifle and start walking through the house so I could see what was going on," he said. "And I hear the banging. ... As I approach the back of the house and I see our back screen room just sticking out 3 feet off the ground, I knew instantly it opened up." (The full report by Shyann Malone, WTSP-TV, Tampa-St. Petersburg, Fla., is carried at the USA Today website: see, "2 houses likely lost because of Florida sinkhole.")

Ironically, repair work at the location had just begun a few days before, according to a report in the Tampa Tribune (for the full story, see: "Sinkhole swallows parts of two Dunedin homes," by Stephen Thompson). The paper reports: "The Dupre family has been engaged in a months-long court battle with its insurance company, Citizens Property Insurance Corp., after a sinkhole was discovered on the property two years ago, said the family's attorney, Jason Salgado." Citizens had proposed a repair plan calling for a deep-compaction grout injection, at an estimated cost of around $100,000, the paper reports, while the family was holding out for a more costly intervention that would have involved shallow grouting as well, along with a possible installation of support pilings.

Nature beat the engineers and lawyers to the punch, however; last week, demolition and backfill was the only work being done. Most of the Dupre family's household possessions were lost, USA Today reports (for the full story along with TV coverage by Eric Glasser of WTSP-TV, see "Crews demolish 1 home that Fla. sinkhole claimed").

Sinkholes are widespread in Florida, USA Today notes—and especially common in Dunedin, where the city actually maintains a list of sinkhole locations. The majority of Florida sinkhole reports come from a region sometimes called "sinkhole alley," which includes the counties of Hernando, Hillsborough, and Pasco.

But as the Los Angeles Times notes, Florida's geology makes sinkholes a risk throughout the state, experts say (see "Is there any place in Florida safe from sinkholes? Technically, no," by Soumya Karlamangla). Still, events like this one stand out: "The people who have been around the city for quite a while, in excess of 30 years, have no recollection of anything ever this big, probably by a factor of three or four times," Dunedin city engineer Thomas Burke said. "For us, this is a major, major situation."

Going forward, Floridians may have more and better information about the sinkhole risk in specific locations: This month, the Florida Geological Survey started a study that experts hope will result in a detailed statewide map of the risk—eventually. The Suwanee Democrat reports on that story here: ("Florida Geological Survey begins sinkhole vulnerability study"). "Field work commenced with documenting multiple sinkholes on private landowner's property in the pilot study area of Suwannee, Columbia, and Hamilton counties," the Democrat reports. "The data will be part of Geologic Information System data that will be compiled and processed in the study … The project is a three year study that will produce two maps: one in the pilot area and the other statewide. The pilot study is slated to end in May 2014, at which point the statewide assessment will begin."

Said Dr. Jon Arthur, Director of the Florida Geological Survey: "It is important to understand the geological character of the ground below us, and this project will provide a map of the relative vulnerability to sinkhole formation in Florida as an important hazard mitigation planning tool."

Meantime, workers in Dunedin were in reactive mode, not planning mode, while residents were trying to get back to their lives, the Tampa Bay Times reported (see: "Officials allow Dunedin sinkhole evacuees to return to homes," by Claire Wiseman and Keyonna Summers). "Workers spent most of Friday and the entire weekend filling in the hole with dirt from a city stockpile," the Times reported. "Officials estimated it would take nearly 600 dump truck loads to fill the 56-foot-deep expanse."