Tunnels under Rome dug centuries ago to supply the building material that would enable the city to grow are now threatening to bring the city crashing down.
Under the Roman streets is a maze of tunnels and quarries that date all the way back to the city's founding, when ancient geologists discovered that the volcanic rocks under the city's soil were perfect for cutting and construction. They created an extensive pattern of tunnels to dig out this precious rock, a labyrinth that has been repurposed over the years as catacombs and even bomb shelters.
But today the tunnels under Rome are creating danger. In 2011 there were 41 instances of streets collapsing, and the next year the number was nearly double.
To combat the problem, a team of geoscientists from George Mason University have set out to map the tunnels under Rome and find the areas at most risk.
The Roman tunnels have gotten a lot of use over the centuries since they were first dug, but today are something of an afterthought for Roman citizens. As a result, it's not known which areas are dangerous and which aren't, researcher say.
"Since they weren't serving any use, people tend to forget what can be a problem," researcher Kysar Mattietti told LiveScience.
The team of researchers are using laser 3D scanning to find weaknesses in the tunnels.
"There might be cracks, so they will be showing as veins almost, or openings, so we map the openings and map any kind of detachment," Mattieti said, adding that some tunnels are only a few inches below the ground. "It's interesting, because at times when you are down there, you can hear people on top."
Mattietti said the team will turn over its maps of the tunnels under Rome to city officials, who can then decide what kind of intervention needs to be done.