On 30 May 2010 a large sinkhole appeared in the middle of Guatemala City, Guatemala. Though commonly called a sinkhole, what happened in Guatemala City was not, strictly speaking, a sinkhole. Experts called it a piping feature because the hole was not made by the same ecological processes as a sinkhole. Sinkholes usually form in karst terrain, which is riddled with pockets of limestone and gypsum, easily eroded minerals. As rainwater passes through the atmosphere it absorbs some carbon dioxide, creating a weak acid that easily erodes through the limestone and gypsum deposits. Instead of forming in karst terrain, the Guatemala City sinkhole formed in tephra terrain, a type of volcanic rock that is extremely susceptible to erosion. Beneath the city a sewer pipe leaked, allowing the soil above it to gradually be worn away. The process sped up, however, when Tropical Storm Agatha hit and inundated the sewer system. The overflow caused the sinkhole to expand and collapse. As a result it swallowed a three story building as well as the majority of a street intersection, killing 15 people.
Contributed by Kimberly Kuxhause
Course: Modern Global Environmental History
Instructor: Dr. Wilko Graf von Hardenberg
University of Wisconsin–Madison, US