"Godzilla of sinkholes": Signs and tests to reduce risk

(CBS News) The sinkhole that apparently swallowed 37-year-old Jeff Bush in Seffner, Fla., was a "Godzilla of sinkholes," according to Michio Kaku, physics professor at the City University of New York.

Bush is now presumed dead, and officials say they will not be able to get into the 30-foot-wide unstable hole in the earth to search for his body.

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Sinkholes are especially common in Florida, which has been dubbed "the sinkhole capital," Kaku explained on "CBS This Morning." The state's rainfall, which moistens the soil and combines with its limestone, makes the state particularly susceptible. Kaku said, "About 50 percent of the state of Florida sits on top of a layer of limestone, carbonate rocks, which are porous, absorbs water and dissolves."

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Kaku said sinkholes are usually detected under structures during inspections, but there are some signals of a sinkhole's presence, such as telephone poles that don't stand upright, doors and windows that don't close properly and cracks in the structure's foundation.

Watch Manuel Bojorquez's full report on Bush and the Florida sinkhole in the video below.

Kaku advised, "If you're thinking of buying a house in Florida, I would think about getting a test with an engineer to look with ground-penetrating radar, which can look several feet under ground, and a cylinder that you actually insert into the soil to sense the solidity of the rock."

Other states in the U.S. at risk for sinkholes include Texas, Missouri, Alabama, Tennessee, Pennsylvania and Kentucky.

Kaku said, "Check your home insurance policy to see whether or not you are covered for sinkholes because testing is advised before you buy a house in one of these areas."

For more with Kaku, watch the video in the player above.