The gigantic sinkhole that opened up in Guatemala City on Sunday has geologists scratching their heads and observers calling for better safety controls, but the more interesting question is: “What to do with a giant Guatemala sinkhole?“
For a small sinkholes in your yard, experts recommend dropping a slab, gravel, or other solid material to the bottom and filling it with clay-like soil. The material will usually settle, and it may be necessary to add more soil over time. However, for a giant sinkhole in your city, experts are flummoxed.
“You need to have some sort of mechanical structural support at the base of your fill material,” says Jim Currens, an expert on sinkholes, caves, and springs with the Kentuck Geological Survey. But Guatemala’s sinkhole is on an exploded scale, and the geological makeup of the region makes predicting the cause and any effective remedies difficult.
The geologist added that the new sinkhole shares remarkable similarities with a sinkhole that formed in Guatemala City in 2007, when a 330-foot-deep sinkhole opened up in Barrio San Antonio, just 15 blocks away from the current one in Ciudad Nueva. That sinkhole is thought to have been caused by a broken storm drain pipe that over time weakened and washed away the ground above it.
“Both of these things occurred in the same general part of town. They look the same,” Sam Bonis, a geologist at Dartmouth College in New Hampshire, who is currently living in Guatemala City, said. “It’s more than a coincidence, especially if they trace” any faulty pipes associated with the 2010 sinkhole to pipes near the 2007 sinkhole. “
Some believe the two Guatemala City sinkholes are linked to government neglect of the area, and are calling for better accountability so that something like this doesn’t happen again with worse results.
The danger should not have been news to officials in Guatemala City, noted Bonis, who used to work for the Guatemalan government’s national geology institute. As part of a volunteer team that investigated the 2007 sinkhole, Bonis co-authored a report warning the Guatemalan government that similar holes will very likely keep appearing unless action is taken to inspect the city’s sewer system for weaknesses.
The government never replied, Bonis said—possibly due to a lack of funds. “There’s a minimum of regulation, because that’s money that the government doesn’t have,” he said. “There’s got to be ways of inspecting the sewer system. These are things that have to be done,” he added.
But geological experts are cautious about assigning blame. Looking at photos of the most recent Guatemala sinkhole, it’s clear that there were preexisting conditions – an underground cavity that may have been present for generations, says Mark Kasmarek, a groundwater hydrologist with the United States Geological Survey (USGS). “Once the roof of that cave becomes compromised through time, it can no longer support what’s on top of it,” he says.
Simply filling the hole won’t help, says Mr. Kasmarek, without first studying the geological makeup of the surrounding area to determine the underlying factors that caused the collapse. [via Christian Science Monitor and National Geographic]