The sudden collapse of a sinkhole in Melbourne's north-east left residents shocked on Tuesday. Here's an explanation of how and why they form.

Most sinkholes form in “karst terrain,” areas where bedrock consists of water-soluble rocks like limestone, gypsum, or salt.

Another day, another sinkhole in Florida. — -- Another day, another sinkhole. The latest one to take place is in Florida. A family had minutes to escape before what appeared to be a sinkhole ...

This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated. Authorities fear a woman in western ...