© DANIEL LECLAIR/Reuters/Corbis
Not all sinkholes are natural occurrences; some accidentally form as a result of human activity. One incredible example of such an incident is the Guatemala City Sinkhole, which measures 60 feet (18 meters) wide and 300 feet (91 meters) deep, and is located in the heart of Guatemala's capital city [source: Than]. Flooding caused by tropical storm Agatha triggered the 2010 event, but geologists believe that leaky pipes actually created the cavern into which the ground fell. When the hole opened up on May 30, 2010, it swallowed a three-story house and a security guard with it, as well as several telephone poles. In an interview with The Christian Science Monitor, David de Leon, the spokesman for the country's disaster response agency said, "The only way to describe it is to say it's huge. It doesn't seem real."
Unfortunately, the ground on which Guatemala City sits is geologically predisposed to sinkholes. The first few hundred meters of soil under the city is composed of particularly loose pumice fill, a volcanic deposit that is easily eroded. This process is sped up when the sewer pipes leak, a problem typically caused in Guatemala when ash from a recent volcanic eruption clogs up the pipes or heavy rains place stress on drainage lines. For these reasons, sinkholes are somewhat common in the country; in 2007, a 100-foot (30-meter) deep sinkhole killed three people and forced the evacuation of 1,000 more [source: Fieser].