Before the earthquake in Venezuela, engineers did not worry that buildings would collapse

CARACAS, Venezuela — For years, engineers analyzing building patterns in Venezuela have expressed a serious concern: That the country’s strong combination of soft soil and tall concrete buildings – many without adequate seismic reinforcement – could lead to catastrophic destruction when a major earthquake strikes.

That doomsday scenario tragically unfolded on Wednesday, when a series of massive aftershocks damaged or collapsed scores of buildings, leaving at least 1,430 people dead, more than 3,200 injured and prompting a search for survivors buried under the rubble. Hundreds remained missing.

“The danger was known,” said Eduardo Núñez Castellanos, a Venezuelan civil engineer who works as a professor and head of the Department of Civil Engineering at the Universidad Católica de la Santísima Concepción in Chile.

The twin earthquakes left a path of destruction from Caracas, the capital, to the coast and elsewhere. The death toll is the highest in Venezuela in more than a century, surpassing the estimated 1,600 in the 6.7 Cumaná earthquake and tsunami of 1929.

Michael Schmitz, professor of geophysics at Simón Bolívar University and the Central University of Venezuela, said he feared that the injured could reach 50,000 people. That’s in the middle of the most likely range estimated by the US Geological Survey, which estimates a 44% chance that the death toll would be 10,000 to 100,000.

It is too early to draw definitive conclusions as to why the damage, and the death toll, was so high. But the first images seem to show collapsed buildings “in some cases higher than 15 stories, with serious structural deficiencies and poor supervision during construction,” Núñez said.

A likely contributing factor: an emphasis on profit over safety.

The widespread damage probably reflects the construction of buildings “in line with the needs of investors rather than buildings that are well designed and built in accordance with the requirements of the earthquake code,” said Núñez. “Unfortunately, this is a common problem in Latin America.”

Núñez was a co-author of a study published in 2023 in the journal Architecture that examined the type of concrete building over 20 stories and built to the minimum requirements of the Venezuelan code. The study found that those structures placed on soft ground had a greater than 80% chance of collapsing when shaken by the force of an earthquake.

“The situation may be more serious in buildings designed according to old codes,” said Núñez.

But outdated safety standards and cheap building codes are likely among the various factors that explain why so many buildings across Venezuela collapsed in this week’s earthquake, the largest to hit the country in more than 125 years.

Contributing factors include concrete buildings designed without taking into account the soft soil conditions of the area, using a type of structural system in buildings taller than 10 stories that are vulnerable to earthquakes, and, “most importantly, insufficient supervision during the construction process due to the weak supervision of the institution,” said Núñez.

“Such institutional control existed in the past, but it has deteriorated under the ruling authorities,” said Núñez.

“The problem is the lack of control over building levels,” Alejandro Giuliano, former director of Venezuela’s National Institute of Seismic Prevention, told Venezuelan broadcaster Radio Mil20 a day after the twin quakes. “It is important to respect the principles of building earthquake resistance.”

The fact that the country had not experienced a deadly earthquake in more than half a century was no excuse.

“One will not be surprised by this event,” said Giuliano. “Venezuela has a history of major earthquakes.”

Most of the worst damage appears to have hit old concrete frame buildings, as well as stone buildings and informal hillside construction, said Ramón Mata Lemus, lead author of the 2023 study and an assistant professor specializing in earthquake behavior at Universidad San Sebastián in Chile.

Another flaw: “soft-floor” buildings, where the lower floor is weaker than the upper floor, making it easier for them to collapse in an earthquake.

“The most serious cases involve the collapse of a complete or partial building, which is often associated with soft-floored methods in open-floor buildings, as well as slab and balcony failure in multi-storey residential buildings,” said Mata, adding that roofs and slabs have fallen in public and residential areas, the road has exploded, stone walls have cracked and buildings have collapsed.

Although the timing of earthquakes is notoriously unpredictable, Venezuela has long been known to be vulnerable.

The country sits on the edge of a major east-west fault that forms the boundary between the Caribbean and South American tectonic plates.

However, international researchers have focused less on the southern edge of the Caribbean plate and the possible consequences of an earthquake in Venezuela, a country of 28 million people, than on the dangers of the northern edge of the plate. Movement along the northern edge of the Caribbean plate caused 7 earthquakes in 2010 in Haiti that killed 316,000 people, one of the worst natural disasters in modern history.

The last major earthquake that shook Caracas so dramatically occurred in 1967, when a magnitude of 6.6 left 240 people dead. There was also a 6.4 magnitude earthquake in 2009, but the epicenter was far from the city.

Another significant earthquake occurred farther to the east. 7 earthquakes in 1997 farther east resulted in 81 deaths, hitting the cities of Cumaná and Carupano, according to the USGS.

A catastrophic earthquake in 1812, with an estimated magnitude of 7.7, may have killed more than 15,000 people. Estimates indicate that a quarter of the population of Caracas died in the quake, Schmitz said.

Wednesday’s 7.5-magnitude earthquake — the second of two earthquakes that struck 39 seconds after the first — is thought to have ruptured a 100-kilometer fault, according to the USGS.

The first fault to break is believed to be in the Boconó system, which is about 25 miles offshore, Schmitz said. The eruption, Schmitz said, moved up the valley and down into the ocean, where the movement was transmitted by the San Sebastián fault, which separates the Caribbean plate from the South American plate.

“It looks like this outbreak was directed from the southwest to the northeast, then completely east,” it said, stopping near the port city of La Guaira, north of Caracas, Schmitz said. According to USGS seismic maps, the earthquake blast sent seismic energy directly through the international airport, which was heavily damaged, and into the port city.

“This may have caused the most damage we have in La Guaira, where up to 100 buildings may have collapsed,” Schmitz said.

Older buildings are more vulnerable.

Buildings built before the early 1980s, and especially those built before the 1967 earthquake, “do not have a lot of earthquake resistance engineering,” he added.

Still, many questions remain about why La Guaira was hit so hard. Feliciano De Santis, president of the Venezuelan Geological Society, said that La Guaira will be the focus of scientists “because the fact that so many buildings have collapsed in that area is really unusual.”

The factors include “old buildings that do not meet modern seismic standards, and hidden faults or structural weaknesses,” De Santis said.

Other issues that may be faced are the construction of buildings – from low-income housing to luxury – with cheap materials and without proper permits. Lack of building maintenance, water leaks, overcrowding, corruption in permitting, and a chaotic state in most governments may also play a role.

Venezuela has been mired in economic and political turmoil for more than a decade. Even so, providing affordable housing to poor and working-class Venezuelans — a longtime bastion of support for the ruling party — remained a central goal of the century-long socialist regime.

Some of the collapsed buildings were built through government programs in La Guaira, and “we always had some doubts about the reliability of the buildings,” Schmitz said.

First responders gathered at a damaged building in the Los Palos Grandes district of Caracas, Venezuela, after a powerful earthquake hit Venezuela and other regions in the Caribbean on Wednesday.

(Jesus Vargas / Getty Images)

Schmitz conducted a study, published in 2020, to help identify areas around Caracas to prioritize buildings that should be retrofitted. The neighborhoods that suffered the most damage would be the most important areas.

Installing earthquake protection has not been a priority for the government in the recession.

Schmitz proposed a similar earthquake study of La Guaira. “I was asking for funding for about six or seven years, but I got it,” said Schmitz.

Lin reported from San Francisco and McDonnell from Mexico City. Mogollon, special correspondent, reported from Caracas.