Dan Doctor on the May 2010 sinkhole in Guatemala City

Residents of an urban neighborhood in Guatemala City experienced the opening up of a giant sinkhole in May 2010. It swallowed a three-story building and left a deep hole. EarthSky spoke with Dan Doctor, a geologist with the U.S. Geological Survey, who studies sinkholes.

Dan Doctor: We wouldn’t consider Guatemala City to be a type of terrain that’s vulnerable to these types of sinkholes.

Doctor said that sinkholes are created when the ground collapses into a void beneath the surface. This usually happens in places where water dissolves away rocks like limestone and gypsum. But that’s not the case in Guatemala City. It’s built on volcanic rock and ash. Heavy rains from Tropical Storm Agatha might have stressed the city’s human infrastructure – water mains or sewer systems – to help create the May 2010 sinkhole.

Dan Doctor: In some cases, you can have rather significant voids formed in the subsurface that later will collapse if they reach the surface.

This sinkhole is just 5 kilometers – or 3 miles – from where another sinkhole in Guatemala City opened in 2007. Local authorities and geologists are still investigating what caused the sinkhole. Doctor added that sinkholes are common all over the world and that in the U.S. Florida is the only state he knows that requires sinkhole insurance for homes.

Dan Doctor: Probably Florida is one area where they occur with such a high frequency and affect so many people.

He said that sinkholes are common all over the world.

Dan Doctor: There are a number of examples where sinkholes have opened up within cities. The one that’s opened up in Guatemala City is quite dramatic indeed.

He added that dealing with an urban sinkhole – especially one of the size and depth of the Guatemala City sinkhole – is not an easy job.

Dan Doctor: One engineering solution is to try to fill it. They seem to be so large and so deep that filling them doesn’t seem like it will solve the problem, but that’s typically what people will do. Still, you don’t just want to throw anything into a sinkhole. Sinkholes are direct conduits to your groundwater system. So you don’t want put anything into it that you wouldn’t want to drink later, especially if you have a well nearby. If a sinkhole did occur and it was going to be engineered properly to be repaired, it’s best to consult a geo-technical firm. And usually they’ll fill it with rock, sediment, or some type of cement or grout.