# 2010 Guatemala City sinkhole

The 2010 Guatemala City sinkhole was a disaster on 30 May 2010, in which an area approximately 20 m (65 feet) in diameter and 90 m (300 feet) deep collapsed in Guatemala City's Zona 2, swallowing a three-story factory. The sinkhole occurred because of a combination of reasons, including Tropical Storm Agatha, the Pacaya Volcano eruption, and leakage from sewer pipes. The sinkhole resulted in one death.

## Background

Overall, the risk of sinkholes occurring in Guatemala City is very high and often unpredictable. One recent, similar sinkhole had collapsed in 2007, forming a pit 100 m (330 feet) deep. The 2007 Guatemala City sinkhole was formed by fluid from a sewer eroding uncemented volcanic ash, limestone, and other pyroclastic deposits underlying Guatemala City. The hazards around the pipe have since then been mitigated, by improved handling of the city's wastewater and runoff. Several rainstorms also contributed to the sinkhole's collapse, as stormwater percolated into the ground, further dissolving the rocks beneath Guatemala City. The 2010 sinkhole was formed for similar reasons.
Sergio Morales, the human rights ombudsman for Guatemala City, verified that residents have been raising concerns about ground instability, including rumblings and fissures, since 2005. Additionally, in a discussion with the newspaper Prensa Libre, Augusto Lopez Rincon, president of a neighborhood association, suggested that heavy traffic from commercial trucks may have contributed to the 2007 sinkhole's development.
Some scientists were surprised by the 2010 Guatemala City sinkhole. "A lot of us who study sinkholes look at this and go, 'wow,' it does seem a little bit bizarre," stated Randall C. Orndorff, a U.S. Geological Survey program coordinator. Geologists familiar with Guatemala, including William Rose, a professor of geological engineering and sciences at Michigan Technological University, agree that the sinkhole was not caused by limestone, which typically plays a role in such disasters. "The area in the city is underlayed by volcanic deposits, and these volcanic deposits make very steep-bounded canyons," said Rose.

## Formation
### Sewage pipes

The sinkhole formed due to volcanic pumice deposits, upon which Guatemala City is built. These deposits were unconsolidated and of low density, allowing easy erosion. According to Sam Bonis, a geologist at Dartmouth College, leaking pipes went unfixed long enough to create the conditions necessary for sinkhole formation because of city zoning regulations and building codes. Bonis also says that the Guatemala City sinkhole is a misnomer: sinkholes have natural causes, but this one was mainly artificial. In addition, according to Bonis, sinkholes are usually formed from limestone, but there is no limestone hundreds of metres underneath Guatemala City. The sinkhole appeared almost perfectly round and seemed to defy reality, raising significant concerns about the structural integrity of the surrounding area and the impact of urban development on natural landscapes.

### Tropical Storm Agatha

Tropical Storm Agatha was first identified as a trough of low pressure off the western coast of Costa Rica on 24 May 2010. On May 29, the depression intensified into a tropical storm and was given the name Agatha. Later that day, the system intensified slightly before making landfall near the Mexico-Guatemala border with winds of 72 km/h (45 mph). By the morning of 30 May, the center of Agatha moved over the highest terrain in Central America, resulting in the dissipation of the low-level circulation. Torrential rains from the storm widened the cavity, eventually causing the collapse of the sinkhole.

### Pacaya volcano eruption

On 27 May, three days before Agatha became a tropical depression, the Pacaya volcano, located about 40 km (25 miles) south of Guatemala City, erupted, killing at least one person and blanketing nearby areas with layers of ash. The eruption prompted officials to shut down the country's international airport. Upon the formation of Agatha, people feared that excessive rainfall from the storm could exacerbate the situation and trigger lahars. This had the effect of clogging the underground pipes with soot, increasing the chances of pipe rupture.

## Collapse and aftermath

Mariela Castañón, a reporter for the daily newspaper La Hora, reported that the ground collapsed suddenly, taking a three-story house that was used as a factory, and possibly a security guard, along with it. Authorities said they could not confirm the security guard's death. One resident expressed their confusion and fear to Castañón, stating, “They [the residents] don’t know whether to stay or evacuate. CONRED hasn’t told them what to do.”
Because of the role played by sewage pipes in the sinkhole's collapse, Bonis, along with other geologists, has demanded that the government inspect the sewer system more regularly.
According to officials, the sinkhole had similarities with another Guatemalan sinkhole which collapsed in 2007, which may also have been formed by ruptured sewage pipes. Both collapses took place along a major stormwater collector/drainage tunnel constructed from volcanic tuff, known as pumice. Following the 2010 collapse, municipal authorities rebuilt the collectors and initiated inspections of the main collector, uncovering issues such as groundwater presence, caverns, and concrete cracks. These findings raised concerns about the stability of the collector and urged for comprehensive geophysical investigations to understand the subsoil conditions surrounding it.
There is controversy regarding the classification of the 2010 Guatemala City incident. Some experts believe it's a "piping feature" incident and should not be considered a sinkhole, because "the hole was not made by the same ecological processes as a sinkhole."
On a wider scale, immediately following reports of fatalities due to Agatha, a state of emergency was declared for Guatemala. On 31 May, the government started to deploy national aid, and donation centers for victims of the storm were opened across the country. According to the Office for the Coordination of Humanitarian Affairs (OCHA), schools in Guatemala were to be closed until at least 4 June.

### Filling in the sinkhole

Immediately after the sinkhole's collapse, there were plans to fill it in with a soil cement made from cement, limestone, and water known locally as lodocreto ("mudcrete"). This substance was also used to fill in the 2007 Guatemala City sinkhole. However, another technique, which geologists call the graded-filter technique, in which the sinkhole is filled with successive layers of boulders, smaller rocks, and gravel, could possibly be a better solution. This is because filling the hole in with cement diverts water runoff to other areas, potentially increasing the risk of sinkholes occurring in other parts of the city. The graded-filter technique, on the other hand, allows water to seep through.