Three in Four Buildings in Colombia Are Not Earthquake-Resistant
Three out of every four buildings in Colombia would not have up-to-date earthquake-resistant design, according to data from the Data Unit calculated from the exposure model of the Global Earthquake Model Foundation (GEM).
The estimate indicates that 74.9% of the country’s buildings would not have been designed under the earthquake-resistant standards currently in force, a figure that contrasts with legislation considered among the most stringent in Latin America.
The calculation is based on GEM’s exposure model, a database containing information on 9.84 million buildings in Colombia. The figure does not mean that three out of every four buildings will necessarily collapse during an earthquake, but rather that they were built without applying the earthquake-resistant code currently in force.
The difference is significant in a country exposed to considerable seismic hazards and that has spent more than four decades updating its standards to reduce the risk of loss of human life.
Three in four buildings in Colombia are not earthquake-resistant
The first Colombian Earthquake-Resistant Building Code was issued in 1984, one year after the Popayan earthquake, which occurred on March 31, 1983.
The earthquake, with a magnitude of around 5.5, caused numerous buildings to collapse and left more than 260 people dead. The disaster became one of the main precedents for the country to establish specific regulations on the design and construction of structures in response to seismic movements.
Fourteen years later came the first comprehensive update. In 1998, through Decree 33, the Government issued the Colombian Earthquake-Resistant Construction Regulations NSR-98, which incorporated new technical criteria and updated the parameters related to seismic hazards. The reform was driven by advances in earthquake engineering and by the experience accumulated in the country.
The next major update took place in 2010. Through Decree 926 of that year, the NSR-10 — one of the most stringent in the region — was adopted. It entered into force on July 15, 2010, replacing the previous regulations.
The regulation incorporated new seismic hazard maps, information on thousands of earthquakes recorded in Colombia, and design criteria based on international advances in earthquake engineering.
A standard designed to save lives
NSR-10 does not seek to guarantee that a building will remain intact after an earthquake. Its main objective is much more specific: to minimize the risk of loss of human life and, secondarily, to protect property as much as possible.
The regulation establishes that a building designed in accordance with its requirements must withstand low-intensity earthquakes without damage and moderate movements without structural damage. In the event of a strong earthquake, it may suffer both structural and non-structural damage, but the objective is for it not to collapse.
That principle explains a fundamental difference between structural safety and the preservation of property. A structure may be seriously damaged after an earthquake and still have fulfilled the essential purpose of the standard if it prevents collapse and allows its occupants to survive. The protection of property is an additional benefit, not the primary objective.
NSR-10 regulates aspects ranging from loads and materials to structural design, geotechnical studies, and technical supervision. It also includes procedures for assessing and strengthening buildings constructed before the regulation came into force.
Schools and hospitals have stricter requirements
Regulations impose greater requirements when a building serves a critical function for society. NSR-10 classifies buildings according to their use and assigns higher levels of importance to those that must continue operating during or immediately after an earthquake.
Hospitals and health centers with services such as surgery, intensive care, neonatal care, or emergency services are part of the group of essential buildings. In these cases, the standard establishes special requirements to reduce the possibility that an earthquake will prevent them from operating.
Schools, universities, and other educational institutions also have a special classification. They are included among buildings intended to serve the community because they may be needed to protect people’s safety after an emergency. For that reason, their earthquake-resistant design criteria are more stringent than those applicable to a building with normal occupancy.
The 74.9% figure does not mean that three out of every four buildings will necessarily collapse during an earthquake. According to the GEM-based analysis, the figure reflects that these buildings were constructed without the code currently in force. This is an important distinction: the age of a building relative to a standard alone does not make it possible to determine how a structure will behave during an earthquake.
The challenge for Colombia, therefore, does not end with maintaining one of the region’s most stringent earthquake-resistant regulations. It also involves identifying, assessing, and, when necessary, strengthening the enormous stock of buildings that were constructed before 2010 and therefore before the current standards.
The standard can establish how the country should be built; the more complex problem is what to do with everything that has already been built, which is now a matter for reflection following the effects of the earthquake last August, which has now claimed 334 lives. Its epicenter was in the department of Choco, the country’s poorest region, which also has the highest number of vulnerable buildings in all of Colombia.