NGDIR News Section-- What should be done when an earthquake hits? Run outside? Or drop, cover and hold on?
It's a question that many instantly must make a reaction to when an earthquake strikes. Californians born in this state might instinctively drop under a table, cover their head and hold tight. Out-of-staters might feel an urge to flee out the door.
As Californians heard as they participated in the global ShakeOut drill at 10:19 a.m. Thursday, a common refrain for many in the United States is to drop, cover and hold on.
There's a reason for that. Many deaths in California's past earthquakes have come from moving objects inside a room- like a loose television or a falling microwave.
The last person to die in a California earthquake, during the 2014 Napa temblor, was a woman who was struck in the head by a television that hadn't been strapped down.
Another big rationale: The most vulnerable part of a building can be the facade. That means that while a building may basically continue standing after an earthquake, the first thing to collapse will be part of its outer wall- posing a deadly hazard for anyone trying to escape.
Before the Napa earthquake, the last two people who died in a California earthquake ran out of an unretrofitted brick building when a temblor struck Paso Robles in 2003. A wall came tumbling down on them, the sidewalk and the street as they exited the building, killing them and covering the sidewalk and street in fallen brick. Experts say had they stayed inside, they would have survived.
Something similar happened during the Sept. 19 Mexico earthquake. In the town of Jojutla in the state of Morelos, about a two-hour drive south of Mexico City, three people died when they fled the historic town hall: as they ran out, parts of the unretrofitted brick building fell, crushing them.
"As they escaped from the building, that bell tower fell and killed the people right on the spot there. So sometimes, it's really dangerous to just run out," said California seismic safety commissioner Kit Miyamoto, who recently visited Mexico.
In California, generally speaking, you're better off staying in the building, said Miyamoto, a structural engineer.
"Chances are, you'll get hit by something on the street," Miyamoto said.
Brick buildings, in particular, tend to fall outward, Miyamoto said, making it generally a bad idea to run out of a brick structure. Miyamoto said he'd also stay inside a steel frame building, as the probability of a steel building collapse is thought to be relatively small.
But for Miyamoto, there are exceptions. One of them is being in an older, brittle concrete building.
Videos taken during the recent Mexico earthquake showed instances where collapses of brittle concrete buildings did not happen immediately. That potentially gave some occupants precious seconds to run outside before a building collapsed.
Brittle concrete buildings have been known to be a design flaw worldwide since the 1971 Sylmar earthquake, but most local governments around the world have done nothing to require owners to go back and strengthen those buildings. The city of Los Angeles in 2015 passed a law requiring those buildings to be retrofitted, but gave owners a 25-year deadline to do it once they are given an order to seismically evaluate the building. The city is still working on preparing its list.
The deadly potential of brittle concrete buildings is well established. Just last month, the seven-story brittle concrete building at Avenida Alvaro Obregon 286 in Mexico City suffered a catastrophic collapse, where columns exploded. Forty-nine people died in that building- the highest death toll of any single site during the Sept. 19 earthquake.
But others in that building escaped death by running to a steel exterior stairwell that had a separate structural system than that of the concrete building. Those that made it to the stairwell survived, said Miyamoto, who consulted with local engineers on the recovery effort at that building.
So, even in the United States, if Miyamoto knows he is in a brittle concrete building, "I [would] probably run out if I was on the ground floor. I know how these buildings are extremely dangerous firsthand," he said.
But he added that being struck by falling objects is still a high risk. "So I would be very careful," he said.
Miyamoto said that if he were in a wooden apartment building with flimsy supports on the ground floor- like to hold up a carport, garage or storefront, known as a "soft-story" building- he would run out if he was on the ground floor, but stay inside if he were upstairs.
So what are you supposed to do in California if you don't have that technical knowledge of knowing what kind of building you're in?
The reality is: You're in a bad situation if you have to make that decision.
Ideally, the owner would have seismically retrofitted the building so occupants can safely drop, cover and hold on without fearing a collapse.
But if you have to make a decision, and you don't know what type of building you're in, Miyamoto advises: "Stay in." He stressed that many people can die from falling walls and objects.
Other experts agree that staying inside is a safer bet in California.
"I would not like to be in a bad building where I would have to make that choice," seismologist Lucy Jones said. "I really can't say, 'Run outside,' if they're in a bad building. I have seen too many situations where people run out of a bad building and the building collapses on them as they ran outside."
Besides the Paso Robles example, Jones cited another example from the 2011 New Zealand earthquake, in which a man in a restaurant in an unretrofitted brick building sits by the window and has to make a split-second decision: Does he run outside, or duck under the table?
Jones said the man decided to drop under the table, where he saw the wall of the building collapsing directly on top of the area where he would've fled.
Running in a strong earthquake poses many hazards, and itself can cause a number of injuries, such as broken legs and ankle sprains.
Jones said in the United States, "I am certain I would drop, cover, hold on. It is not a guarantee. But I think the odds are better," given that she knows of too many situations where people fleeing outside were hit as the building collapsed outward.
"I know it goes against every emotional reaction a human being has to earthquakes," Jones said. But, she added, "I know it's the safest thing here."
"If I thought it was a very bad building, I would try harder to get to a sturdy table," she said.
Jones pointed out to a photo of a collapsed building during the 1985 Mexico earthquake. On a couple of floors, desks can be seen still intact, appearing to prop up the ceiling.
L.A., Santa Monica and West Hollywood have passed laws requiring owners of brittle concrete buildings to retrofit them. But most other local governments in California have not done so.
Mark Benthien, director of outreach for the Southern California Earthquake Center and global coordinator of ShakeOut, suggested that a blanket recommendation to flee buildings in California when an earthquake hits is a bad idea. Even in Mexico, Benthien said, there were videos of the facades of buildings falling: "If people had been running out of the building, they would've been hit."
The big problem is not knowing what will happen.
"If you know your building is going to collapse, and you know you have time to get out, like if you're on the first floor, then maybe get out," Benthien said. "But unfortunately, you might not know if you're going to get out."
If you can't get out, then a better bet out of many terrible options may be to get under a sturdy desk and hope that you'll be in a "survivable void space" in which you'll be able to survive and get rescued.
"But if everybody runs outside, or is running, you're going to have a lot of people who get injured," Benthien said.
For every building that catastrophically collapses, there are far more buildings in which objects or just the facade of the building falls, and in which running would be far more potentially deadly than getting under a desk.
"The general advice for people is that they're going to be safer if they don't run outside. Because things fall off a building before things fall down," Benthien said.
By LOS Angeles Times