Before Venezuela earthquakes, engineers worried buildings could collapse
CARACAS, Venezuela — Engineers analyzing Venezuela’s construction patterns have expressed a major concern for years: That the country’s unstable combination of soft subsoil and tall concrete structures (many of which lack adequate seismic reinforcement) could lead to catastrophic destruction when a major earthquake strikes.
This doomsday scenario played out in devastating fashion on Wednesday, as two back-to-back massive earthquakes damaged or collapsed scores of buildings, leaving at least 1,430 dead, more than 3,200 injured, and setting off a desperate search for survivors beneath the rubble. Hundreds of them are still missing.
“The risk was known,” said Eduardo Núñez Castellanos, a Venezuelan structural engineer who works as an associate 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 the capital Caracas to the coast and elsewhere. The death toll is on track to be Venezuela’s deadliest in more than a century, surpassing an estimated body count of 1,600. magnitude 6.7 1929 Cumaná earthquake and tsunami.
Michael Schmitz, a professor of geophysics at Simón Bolívar University and the Central University of Venezuela, said he feared losses could reach 50,000 people. That’s the midpoint of the most likely range estimated by the U.S. Geological Survey, which estimates there’s a 44% chance the death toll will be between 10,000 and 100,000.
It is too early to draw firm conclusions as to why the damage and death toll were so high. But Núñez said initial photos showed collapsed buildings “in some cases higher than 15 stories, with significant construction deficiencies and poor supervision during the construction phase.”
One likely contributing factor: an emphasis on profit over safety.
Núñez said the widespread damage likely reflected “building construction tailored to investors’ needs rather than structures designed and constructed in compliance with earthquake code requirements.” “Unfortunately, this is a common problem in Latin America.”
Núñez co-authored a book to work We reviewed one type of concrete building, published in Buildings magazine in 2023, that was more than 20 stories high and built to minimum Venezuelan code requirements. The research found that buildings built on soft ground have a greater than 80% chance of collapsing if shaken by a strong earthquake.
“The situation may be even more critical in buildings designed according to the old rules,” Núñez said.
But outdated safety standards and a mindset of building cheaply are among several factors that explain why so many buildings collapsed in Venezuela this week, the biggest earthquakes to hit the country in more than 125 years.
Contributing factors include concrete buildings designed without consideration of local soft soil conditions, the use of some form of structural system in buildings taller than 10 stories that are vulnerable to earthquakes, and “most importantly, inadequate oversight of the construction process due to weakened institutional control.” said Núñez.
“Such institutional control existed in the past, but has deteriorated under the current governing authorities,” Núñez said.
“The problem is the lack of control in building standards,” Alejandro Giuliano, former director of Venezuela’s National Institute of Seismic Prevention, told Venezuelan broadcaster Radio Mil20 a day after the twin earthquakes. “It is essential to comply with earthquake-resistant construction norms.”
The fact that the country had not experienced a mass-casualty earthquake in more than a quarter of a century was no excuse.
“It is impossible to be surprised by this incident,” Giuliano said. “Venezuela has a history of major earthquakes.”
Ramón Mata Lemus, lead author of the 2023 report, said much of the worst damage was caused by old concrete-framed buildings, as well as masonry buildings and informal hillside construction. to work and an assistant professor specializing in seismic behavior at Universidad San Sebastián in Chile.
Another flaw is “soft-storey” buildings, where the ground floor is less durable than the upper floors, making it easier to topple over in an earthquake.
“The most serious cases involved full or partial building collapses, often associated with soft floor mechanisms in buildings with open ground floors, as well as floor and balcony failures in multi-storey residential structures,” Mata said, adding that ceilings and floors collapsed in public and residential areas, pavement was torn, masonry walls cracked and building facades fell.
Although it is unpredictable when earthquakes will occur, it has long been known that Venezuela is vulnerable.
The country lies on the edge of a giant east-west fault, the boundary between the Caribbean and South American tectonic plates.
But international researchers have focused less on the southern edge of the Caribbean plate and the potential seismic consequences for Venezuela, a population of 28 million, than on the dangers at the plate’s northern edge. Movement at the northern edge of the Caribbean plate caused the magnitude 7 earthquake in Haiti in 2010, killing 316,000 people; This is one of the worst natural disasters in modern history.
The last major earthquake to dramatically shake Caracas occurred in 1967. magnitude 6.6 It caused the death of 240 people. There was also a magnitude 6.4 earthquake in 2009, but the offshore epicenter was further away from the city.
Other significant earthquakes occurred further east. A. size 7 An earthquake farther east in 1997 hit the cities of Cumaná and Carupano, resulting in 81 deaths, according to the USGS.
The devastating earthquake of 1812, estimated at magnitude 7.7, may have killed more than 15,000 people. Schmitz said estimates show that a quarter of the population of Caracas died in this earthquake.
Wednesday’s 7.5-magnitude earthquake – the second of two earthquakes that occurred 39 seconds after the first began – is thought to have ruptured about 100 miles of fault, according to the USGS.
The first fault to rupture is believed to be in the Boconó system, about 40 kilometers from the coast, Schmitz said. Schmitz said the rupture moved rapidly from the valley towards the sea, where the movement was transferred to the San Sebastián fault, which separates the Caribbean plate from the South American plate.
“It appears that this rupture was directed from southwest to northeast and then completely eastward,” Schmitz said, standing just near the port city of La Guaira, north of Caracas. According to USGS tremor intensity maps, the earthquake rupture sent tremor energy directly to the heavily damaged international airport and from there to the port city.
“This probably caused very heavy damage in La Guaira, causing as many as 100 buildings to collapse,” Schmitz said.
Old buildings are particularly vulnerable.
He added that buildings built before the early 1980s, especially those built before the 1967 earthquake, “did not have much earthquake-resistant engineering features.”
Still, there are many questions about why La Guaira was hit so hard. Feliciano De Santis, president of the Venezuelan Geological Society, said La Guaira will be the focus of scientists “because the fact that so many buildings in that area have collapsed is really abnormal.”
De Santis said factors include “older buildings that do not meet modern seismic standards, as well as hidden defects or structural vulnerabilities.”
Other issues that will likely attract attention are the construction of buildings, from low-income housing to luxury condominiums, with cheap materials and without proper permits. Lack of building maintenance, water leaks, structural overloading, corruption in the issuance of permits and the general chaotic situation in much of the government may also play a role.
Venezuela has been in economic and political turmoil for more than a decade. Yet providing affordable housing to poor and working-class Venezuelans (the basis of the ruling party’s long-standing support) remained a central tenet of socialist rule for more than a quarter-century.
Schmitz said some of the collapsed buildings were built through government programs in La Guaira and “we always had some doubts about the reliability of the structures.”
First responders gathered at a collapsed building in the Los Palos Grandes district of Caracas, Venezuela, after powerful earthquakes hit Venezuela and other parts of the Caribbean on Wednesday.
(Jesus Vargas/Getty Images)
Schmitz conducted a study to workIt was published in 2020 to help identify areas around Caracas and prioritize buildings that need retrofitting. Heavily damaged neighborhoods would be such high priority areas.
Installing seismic protections has not been a priority for a government in economic freefall.
Schmitz proposed a similar seismic study for La Guaira. “I’ve been asking for financing for about six or seven years, but I haven’t been able to get it,” Schmitz said.
Lin reported from San Francisco and McDonnell from Mexico City. Mogollón, a special correspondent, reported from Caracas.
