Venezuela quake: Devastation is urgent warning for California

The devastation wrought by two massive earthquakes that hit Venezuela on Wednesday offers a sobering warning for California and other seismically sensitive regions that catastrophic tremors could wreak havoc on urban areas.

It will take days to assess the full extent of the damage. But the videos show horrific but now predictable images of entire blocks flattened and basic infrastructure in shambles.

Images of the most serious damage in Venezuela appear to involve the collapse of “non-ductile concrete buildings,” a type of building construction also present in California, according to Maria Mohammed, president of the Structural Engineers Assn. Southern California.

“When we look at the photos from the news, it seems that most of the buildings we see collapsed are inflexible concrete buildings,” Mohammed said. Such concrete buildings do not have enough steel to prevent the brittle concrete in the columns from bursting when shaken in an earthquake.

The U.S. Geological Survey said non-ductile concrete buildings are one of the building types “most likely to kill people during an earthquake.”

The discovery of the fatal flaw behind non-ductile concrete buildings occurred during the 6.6 magnitude Sylmar earthquake of 1971. Among the concrete buildings that collapsed in this earthquake was the 46-year-old Veterans Administration hospital in San Fernando, where 49 people died.

More concrete buildings collapsed during the 1994 magnitude 6.7 Northridge earthquake, causing the partial collapse of the Kaiser Permanente building and Bullock’s department store.

Minimum building requirements have changed in the United States since the 1970s; The construction of non-ductile concrete buildings was banned and a better configuration of steel reinforcement to resist shaking was mandated. In the last decade, several local governments, such as those in the city and county of Los Angeles, torranceSanta Monica and West Hollywood have requested seismic reinforcing of fragile non-ductile concrete buildings, but the deadline for reinforcing them is years away.

But many other cities in California have not implemented such retrofit rules. SanFranciscoUntil now, only concrete building owners were required to submit an online screening form with information about their building’s design.

Meanwhile, flimsy concrete buildings continue to collapse in earthquakes around the world. Taiwan New Zealand in 1999, New Zealand in 2011, Mexico in 2017, Türkiye and Syria in 2023 and earlier this month. PhilippinesA viral video shows workers running away from the shaking building housing Jollibee’s fast food restaurant before it catastrophically collapsed.

It will take time to evaluate construction codes and practices in the Venezuelan cities that were devastated on Wednesday. A study published in 2020, discussed how experts might recommend reinforcing risky buildings. Another report published in 2023 made a new recommendation: offer It will be included in Venezuelan earthquake codes “to improve the safety” of buildings.

Some of the deadliest earthquake-triggered building collapses in other countries around the world have been affected by corruption, uneven application of building codes and poor quality. structure. government in new zealand investigation It was revealed that one of the engineers who designed one of the buildings that resulted in the death of 115 people worked well beyond his level of experience.

California has gradually increased earthquake safety codes for new construction over the past century after major earthquakes such as Long Beach in 1933, Sylmar in 1971, Loma Prieta in 1989, and Northridge in 1994.

However, concerns about old construction continue. While many old brick buildings in Los Angeles have been renovated, other types of buildings have not.

Engineers have warned that a major vulnerability for California is concrete buildings built to codes that existed in the 1970s or earlier and have not been updated and are likely to collapse. A notable example of this was the partial collapse of the then brand new Olive View Medical Center in Sylmar, which had opened to higher standards just months before the 1971 Sylmar earthquake; three people died.

The USGS said it was possible that about 50 low- and mid-rise old concrete buildings would collapse in a 7.8 magnitude earthquake in Southern California in 2008. In a ShakeOut scenario, there could be 800 people in fully collapsed concrete buildings and 7,000 people in partially collapsed structures, the USGS said.

The massive earthquakes that hit Venezuela on Wednesday caused buildings in the country’s capital, Caracas, to collapse, with 7.2 and 7.5 magnitude tremors occurring 39 seconds apart at 18:05 local time, according to the US Geological Survey. An estimated 20,000 people experienced “severe” shaking, as defined by the Modified Mercalli Intensity Scale, sufficient to throw buildings off their foundations and cause major damage to major buildings.

The epicenter, or point of origin, of Wednesday’s largest earthquake occurred in Yaracuy province, about 100 miles west of Caracas, but it then ruptured a long fault line to the east, sending jarring energy into Caracas. “Very strong” or “severe” tremors were felt in Caracas, according to crowdsourced data sent to the USGS.

“This is one of those very damaging earthquakes because you’ve combined a very large event with the residence of a large number of people,” Caltech research assistant seismologist Lucy Jones said on Wednesday.

Wednesday’s largest earthquake appears to be the largest Venezuela has experienced in 125 years; It was likely eclipsed by the estimated magnitude 7.7 earthquake that struck off the nation’s coast in 1900, killing 21 people, according to the USGS historical earthquake database. The closest earthquake of magnitude 6 or greater in recent memory was an earthquake near Caracas. 6.6 magnitude earthquake The incident that killed 240 people in 1967 revealed the city’s vulnerability to earthquakes.

The number of injured may increase. computerized calculations Based on the shaking area and intensity, the USGS suggests there is a 40% chance that deaths will range from 10,000 to 100,000, and a 36% chance that deaths will range from 1,000 to 10,000.

“In general, the population in this region lives in structures vulnerable to earthquake shaking,” the USGS said.

Some parts of Venezuela may have perceived the two earthquakes as a single tremor event that lasted for a very long time. Caltech geophysics professor Zhongwen Zhan, director of the Caltech Seismology Laboratory, said during the briefing that a seismic station in Venezuela observed what appeared to be a “fairly continuous event” between two earthquakes.

“This is not surprising. A magnitude 7.2 earthquake can last half a minute, so the two earthquakes basically merge, so we could potentially expect there to be a reclassification later; it may not be a separate foreshock,” Zhan said.

Caracas’ seismic risk is similar to the risk faced by Los Angeles and San Francisco, Jones said, because all three cities are near the tectonic plate boundary and “so have historically experienced larger earthquakes.” “For a geologist, this is not surprising.”

The speed at which tectonic plates slide past each other in Venezuela is similar to how quickly seismic stress accumulates on the San Andreas fault in California, Jones said.

“This is the kind of earthquake we talk about when we talk about the San Andreas risk to California,” Jones said. The similarities are striking; this earthquake was just outside Caracas, and the San Andreas fault is about 20 miles from the edges of the city of Los Angeles and “runs through the Inland Empire,” including San Bernardino.

California will likely fare better than Venezuela on Wednesday, but a magnitude 7.8 earthquake in that state could still be devastating. A USGS simulation of a hypothetical magnitude 7.8 earthquake on the San Andreas fault said 1,800 casualties were plausible and hundreds of billions of dollars in losses could occur with massive fires (perhaps 10 times the size of those in Altadena and Pacific Palisades) ravaging the region due to water shortages.

“That’s why we’re very concerned,” Jones said.

The Venezuela earthquake came about seven hours after a 5.6 magnitude earthquake struck Northern California’s Mendocino County. Jones said it was a much smaller earthquake, perhaps one-thousandth the size of the Venezuelan earthquake.

About 25 minutes after the Venezuela earthquake, a 6.9 magnitude earthquake occurred on Japan’s east coast, about 20 miles from the town of Kuji in Iwate prefecture, where “strong” shaking was felt. However, the USGS estimated that the likelihood of death or serious economic damage was low because the structures there were generally resistant to earthquake shaking. The region was heavily affected by the 9.1 magnitude earthquake and tsunami that started off the east coast of Japan in 2011, leaving more than 20,000 dead or injured.

“It was offshore and so the shaking that people are getting (the earthquake is coming to them from farther away) they’re getting lower levels of shaking,” Jones said. Additionally, “the construction in Japan was designed to handle that strong earthquake shaking and so it doesn’t look like there was significant damage there.”

Jones said there is no scientific basis to suggest that earthquakes near Venezuela, California and Japan are linked.

Here are ways people in California prepare for earthquakes, including having property owners evaluate whether renovations are necessary, even if a city ordinance doesn’t require them. Jones noted that the state is offering grants through its Earthquake Support + Bolt program to partially cover the cost of renovating older single-family homes that could slide off their foundations in an earthquake.

Many apartment buildings have a flimsy first floor supported by thin supports to accommodate parking lots, garages, or storefronts. Some cities in California have requested that these “soft-story” buildings be retrofitted, but many have not. There are also numerous cities, especially in the Inland Empire, that have old brick structures that may collapse in an earthquake, but do not need to be reinforced or demolished.

Structural engineers have also warned of the potential vulnerability of some older steel-framed skyscrapers. Torrance, Santa Monica and West Hollywood all require steel moment frame buildings to be evaluated and strengthened if necessary, but the city of Los Angeles has no such requirement.

People can also take steps to update their furniture, such as fixing televisions to walls, attaching bookcases to walls, installing earthquake-resistant latches on kitchen cabinets, and purchasing picture frame hooks from a hardware store, which can help prevent glass frames from shattering on the floor. Officials recommend storing one gallon of water per day per person for at least three days, ideally two weeks.

“The other thing I would say strongly is talk to your neighbor. Do you have a family plan? Do you have a neighborhood plan?” said Jones. “That’s what saves you from disaster, and the best earthquake plans are the ones you make with your neighborhood, your church, your school.”