- Veronica Cedillos and Gerardo Suarez debunk 13 myths about earthquakes and earthquake safety.
- They explain why doorways aren’t safe, and why the “Triangle of Life” is actually dangerous.
- They also explain how seismologists and experts work together to prepare for earthquakes.
- Visit the Business section of Insider for more stories.
Following is a transcript of the video.
Gerardo Suárez: “The ground can open up during an earthquake.” Everything disappears in the earth. Earthquakes don’t operate like that. “You should always try to get outside” when an earthquake occurs.
Veronica Cedillos: In the midst of running, you can get seriously injured.
Suárez: “California will fall into the ocean.” Well, the answer is of course not.
Hello, I’m Veronica Cedillos. I am a structural engineer by training. I am currently president at GeoHazards International.
My name is Gerardo Suárez. I am a senior scientist at the Institute of Geophysics at the National University of Mexico. Today, we are debunking myths about earthquakes and earthquake safety.
Suárez: These are myths from social media. “Doorways are a safe place to take cover during an earthquake.” And, Veronica, I think you’re better prepared than I am.
Cedillos: Yeah. This is definitely a myth. Something we’ve heard from, I think, past, very old construction. And that was when the frame around doors was actually part of the skeleton of the building that really kept up the building, so it was a really strong part of the structure. Modern construction does not have that. In fact, the doors are not in any way stronger, so they’re really not helpful or very protective during earthquake shaking. And, in fact, I would say that holding onto a doorframe, if you have a swinging door during strong earthquakes, you can actually get quite injured.
Suárez: There’s no universal recipe to be safe. It depends on how your house, your apartment building is built and where you live, even in what part of the city you live in.
Cedillos: The work has to happen before the earthquake in terms of finding a safe place. Create a safe place. So, trying to figure out, OK, if there was shaking, looking up in your own home and seeing what could fall over or topple that can be heavy.
Suárez: This question is about the “Triangle of Life.” Will it save you?
Cedillos: You can see some of these voids after the shaking has happened, but what you don’t see is what happened in between. And so it may have been that this very dense object, with strong shaking, might’ve moved quite a distance, or those objects can actually topple, and in many cases it can actually be way more dangerous to be there. If you could get under a sturdy table, that would probably be best. Protecting your head and neck are really important.
Suárez: But yes, there may be some cases where people were saved because they accidentally were trapped between a very strong object and perhaps a beam or something that fell down. But I think it is more circumstantial evidence than anything else.
Cedillos: “Earthquake-proof buildings are indestructible.” I want to make a distinction between earthquake-proof and earthquake-resistant. So, in practice, we don’t usually design or build earthquake-proof buildings. So, a similarity might be waterproof versus water-resistant. And I think for a very long time we went from really trying to ensure that our designs were life-safe. So they really were protecting the occupants inside the building. Now, what we’ve learned as we’ve seen earthquakes in other parts of the world, that doesn’t mean that you’re not going to have damage to a building. And so it may be that after an earthquake, your building no longer functions and you can no longer stay in it. And if that happens on a grand scale, all of a sudden you have an entire city that can’t be housed or buildings that can’t be used for businesses. And so it really affects the economy and the community as a whole. And now there’s a big movement to try to move towards designing not just for life safety but actually what’s called “functional recovery,” with the idea that you can recover in a shorter time span.
“Small earthquakes prevent bigger ones from happening.”
Suárez: Well, I bear bad news for people who believe in this, because people do say, “Oh, it’s been very active, lots of small earthquakes, so they’re taking up the energy that’s concentrated on the fault.” And indeed, yes, they’re releasing some energy. And that happens in places that we call subduction zones, where one tectonic plate goes under another one, that there are dozens, literally hundreds of small earthquakes in a certain time frame in a certain place. But, eventually, in these active faults you will have a major earthquake. And by major, I would just say larger than magnitude 7.5. That is required to release the energy that has been accumulated.
Cedillos: I think there’s a misconception that it’s only the very big one that’s going to be the most dangerous. But, in fact, what we see is that even with moderate earthquakes, there can be a lot of actually injuries and death, even. Unreinforced chimneys, we know, are very vulnerable to collapse under very low levels of shaking. And those falling into a household, for example, can be very dangerous.
Suárez: “We are overdue for a major earthquake.” So, when we say “overdue,” we imply that we know the earthquake should have occurred before, and it hasn’t. And this is something that we simply do not know.
Cedillos: Prediction versus forecasting. I think that’s where we get a little bit of a misunderstanding, because we can forecast, usually in probabilities, and say there’s a probability that there’ll be this size of earthquake within this region. And so we really can’t predict specifically where and when an earthquake will occur.
Suárez: Everyone who lives in a seismic area should be aware. Everyone should have a kit at home. You need to have some water, you need to have a lamp light, and so on and so forth.
OK. These are myths from pop culture.
“You should always try to get outside” when an earthquake occurs.
Cedillos: For the most part, this is probably not a very safe practice, to run outside during earthquake shaking, especially because many times things can fall outward. In the midst of running, you can get seriously injured. In the one situation where it is a good idea, and that’s in an adobe, earthen building that is not strengthened or reinforced in some way. Those buildings are particularly dangerous when you have a heavy roof. If you’re on the ground floor of one of these buildings, you do want to try to run out, assuming you’re running out into a space that’s open. But if you’re already outside, stay outside. You want to try to get away from building facades, because there can be bricks falling. You want to be very careful about that.
Suárez: “The ground can open up during an earthquake.” It is a myth that has to be debunked. This myth comes very much from earthquake movies, where you see that during the earthquake, there is a big crack that opens, and it swallows buildings and people and cars. And then it just, boom, it shuts tight, and everything disappears in the earth. And this doesn’t happen. Earthquakes don’t operate like that. In certain types of soils, cracks are formed because of the very strong shaking, but these are relatively shallow cracks. I mean, they wouldn’t swallow, not even a small cat. And probably that image was extrapolated into this fantastic idea of these huge mouths as swallowing everything in its surroundings. So, no. The answer is definitely not.
“In the US, a big enough earthquake on the West Coast could be felt on the East Coast.”
It will be so big that even though it’s happening here in California, you will feel it on the East Coast.
Cedillos: No, that is not what we expect! It’s just a big enough distance that we don’t expect for anyone to feel any significant shaking on the East Coast from a large earthquake on the West Coast. The plates and the type of rock that we have on the East Coast versus the West Coast, they are different. And so what happens is that the type of rock that we have in the East Coast, the earthquake waves, seismic waves can actually travel much further. So what happens is that in the East Coast, you’ll be able to perceive or feel significant shaking actually much further distances from the epicenter, or the origin of where the earthquake shaking started. As opposed to the West Coast, where those seismic waves, actually that energy is absorbed much quicker, and so it doesn’t travel as much of a far distance.
“We are able to predict earthquakes.”
Suárez: This is a very simple answer. It is no. No, we cannot yet predict earthquakes. And I added the word “yet.” I wouldn’t say that now it continues to be the goal of seismology to be able to predict earthquakes. I believe the goal of everyone who works in seismology or in engineering seismology, it is not to predict earthquakes, but to be prepared for major earthquakes, to understand the phenomenon.
Cedillos: There are use of what we call “earthquake scenarios,” and what those are, they’re not predictions, but they’re incredibly useful in the sense that many times we don’t see changes in codes or anything until after there’s an earthquake and we learned everything that went wrong. We use the tool of an earthquake scenario – so, we choose a believable earthquake that could happen in a certain area to try to understand what may be some of the key vulnerabilities around that particular city or area, whether it’s the water system or the housing or the hospitals, to try to get ahead and try to instill safer practices or actions that will help us address those vulnerabilities before an earthquake occurs.
Myths experts hear the most.
Suárez: So, “In tall buildings, it is always safer to be on a lower floor.”
Cedillos: If you’re in a tall building, especially in a place where the codes are usually followed, it’s likely that they’re actually under even higher requirements in terms of design, and so, as long as the building is safe, it doesn’t matter too much where you are. That being said, if there is more movement, that’s when it is really, really important to make sure that the contents within your house, or whatever, your office building, are secured and that they can’t fall over and topple over and hurt you.
Suárez: “California will fall into the ocean.” Well, the answer is of course not. You know, California would not fall into the ocean. Part of California, the westernmost sliver of California, it sits on the Pacific Plate, whereas the rest of California sits on the North American Plate. And these two plates move one relative to one another at a rate of about 5 to 6 centimeters per year. So, yes, when people say Los Angeles is going to end up near Anchorage, well, yes, eventually, but in many millions of years.
OK. “There’s such thing as earthquake weather.” But no. There is no season for earthquakes, there is no weather for earthquakes, and there’s no specific time for earthquakes. You might be thinking of a very convenient time that an earthquake would happen. It might be very inconvenient.
Cedillos: When you think about earthquake shaking, you have to think about different times of the year and different times of the day. You might be sleeping, or it might be winter. It might be raining. And so the danger is that you’re not thinking of all these scenarios.
“Bigger earthquakes happen under full moons.”
Suárez: People connect that to the pull of tides. And it’s true. We are very used to the ocean being deformed and the water level changing due to the tides depending on the cycles of the moon. And this also happens in the earth. The earth itself, the continents themselves are deformed because of this rotation of the moon. The deformation is not large enough to produce earthquakes. And people have looked at statistics to see, and there has been absolutely no correlation at all.
Cedillos: A lot of the actions that you need to take to really protect communities and protect people need to be taken years before the earthquake actually arrives.