Colombia has one of the most demanding building codes in Latin America, but 3 out of 4 buildings would not have earthquake-resistant design

At 7:34 a.m. on Monday, August 10, the largest magnitude earthquake recorded in Colombia in the 21st century occurred, according to the Colombian Geological Service (SGC). It was a 7.4 and had its epicenter in San José del Palmar, in Chocó, at a depth of 103 kilometers.

The earthquake was of intermediate depth and originated within the Nazca plate, which is subducting beneath the Pacific. That depth explains why it was felt in 28 of 32 departments, according to the SGC, and why five of them were severely affected (Chocó, Valle, Caldas, Quindío, and Risaralda).

Although the country, on paper, has regulations to prevent building collapses and structural damage, the current regulation is still from 2010 and has not had a comprehensive update, beyond partial modifications such as Decree 1401 of 2023, which incorporated a rule to reduce vulnerability of informal masonry housing. This despite the fact that seismic information from the last 16 years already exists.

Colombia’s seismic history shows that magnitude does not determine devastation. On January 31, 1906, off Tumaco, Nariño, an 8.8 magnitude earthquake caused a tsunami and left more than 1,500 dead, according to historical estimates, scattered due to the low population density of the coast. The contrast comes with two earthquakes from the same northwest region. In 1992, a 7.2 magnitude quake near Murindó caused 10 deaths because it struck a sparsely populated area. Seven years later, a smaller magnitude quake devastated a city: the Armenia earthquake on January 25, 1999, was magnitude 6.1 and according to SGC records left 1,185 dead, 8,536 injured, and 35,972 homes destroyed or uninhabitable, because it hit a dense and vulnerable urban area.

The Data Unit calculated the number of deaths per 100,000 inhabitants in the year of each event, using death figures from the SGC and UNGRD and population series from the National Administrative Department of Statistics (Dane). In Armenia (1999) the rate was 2.94; in Popayán (1983), 0.89; and the August 10, 2026 event, despite its 7.4 magnitude, records a rate of 0.63.

The first earthquake-resistant code emerged after the Popayán earthquake of 1983. One year after the seismic event, Decree 1400 of 1984 was issued to seek protection of buildings so fewer people would die from structural collapses.

Fourteen years later, in 1998, the regulation was updated to NSR-98, which included new technical parameters and seismic threat assessments. In 2010, through Decree 926, it was updated again.

That, the NSR-10, the current national code, is considered one of the most demanding in the region.

According to the document, it should be updated periodically to reflect advances in design techniques and experiences with recent earthquakes.

In that sense, buildings are designed to withstand a strong and rare earthquake, the size of which on average occurs once every 475 years. Essential buildings, such as hospitals, and those with large occupancy, like schools, are held to even higher standards by the code.

Real earthquake resistance depends on three factors that the code alone does not guarantee. They are compliance, the condition of the existing or informal building stock, and the reinforcement of what exists.

Although there is no official consolidated figure on how much of the building stock was constructed without the current code, the Data Unit estimated it based on the GEM exposure model, a database that includes 9.84 million buildings in the country. According to that model, about 3 out of 4 buildings would not have earthquake-resistant design (74.9 percent).

The National Professional Council of Architecture estimated in 2023 that at least 52 percent of buildings predate the NSR-10 and that, of every five new homes entering the market, three are informal.

Meanwhile, Dane, in the 2018 census, reports that 36.6 percent live in housing deficit, meaning in homes with structural or remediable deficiencies.

The District Institute of Risk Management and Climate Change (Idiger) and the document Seismic Risk in Colombia, by UNGRD and the Seismic Engineering Association, established that 83 percent live in zones of high seismic threat.

The country lies at the confluence of the Nazca, South American, and Caribbean plates. Among its main seismic sources are the Pacific subduction, the Romeral fault system, and the Bucaramanga Seismic Nest.

To understand which areas are more exposed, two often-confused issues must be separated. One is threat, which measures how strong shaking can be in a place due to geological reasons, such as faults or soil type, and is what seismic maps show. The other is risk, which combines that threat with how much is built in the area and how fragile the construction is. A threat map shows where strong shaking can occur and risk shows how much can be lost when it happens.

The difference is seen in Bogotá. On the national map, the city appears as intermediate threat, but its soil type demands more robust construction, experts say. That is why District Decree 523 of 2010 adopted a microzonation that requires building with higher standards than the national code.

The UNGRD Risk Atlas and the GEM global model agree that, to compare threat, exposure, and vulnerability, the expected annual loss is useful, which estimates how much money in assets would be lost on average per year due to earthquakes.

That figure can be read in two ways. The first is absolute loss, which is the total money lost each year. Valle del Cauca, Bogotá, and Santander lead. According to GEM, Valle loses an average of 109.8 million dollars per year and Bogotá, 98.9 million.

The second is relative loss, which is the fraction of exposed assets lost. Here the list changes and Chocó leads. In dollars, the estimate is that this department loses 8.3 million per year, but proportionally it loses more than triple the national average: for every 1,000 dollars built, 1.6 is lost annually, compared to 0.5 in the country.

The distinction matters because it points to two different problems. Bogotá loses a lot of money in total, even if it is a smaller part of its immense exposed wealth. Chocó loses little money, but it is almost all it has. Experts indicate that relative loss says more than absolute loss to know where an earthquake would be more devastating.

In that vein, reviewing the calculations, high relative risk is concentrated in the Pacific west —Chocó, Valle del Cauca, Cauca, and Nariño— where much of the severe damage from the August 10 earthquake was concentrated, and in a strip of Santander near the Bucaramanga Seismic Nest.

Both models agree on that ranking, with Chocó first in relative loss, although they differ in amounts. The UNGRD Atlas measures several threats at once and estimates higher losses, while GEM measures only the earthquake. Still, they point to the same department with different figures. Neither measures what comes after the emergency, such as soil liquefaction, landslides, tsunami, or road damage.

The Atlas adds a social component to that measurement. It builds an index of socioeconomic fragility for each municipality, based on the idea that the same tremor hits harder where poverty, informality, and institutional weakness converge. Chocó has all those factors. It is one of the poorest departments in the country, with a multidimensional poverty of 30.8 percent in 2025 according to Dane, was the epicenter of the earthquake, and has a building stock mostly without codes, with few resources to reinforce or rebuild. In other words, inequality ends up multiplying the risk.

DATA UNIT

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