- What you do the instant an earthquake hits matters a lot.

The right decision could save your life, but if you watch the first 100 videos on YouTube that capture the exact moment an earthquake hits, almost no one does the three things that authorities tell us to do.

Drop, cover, and hold on.

So we're going to talk to one of the foremost experts on earthquakes in the world, Chris Goldfinger.

In a previous episode he helped us understand why the Cascadia megaquake is likely to be the worst disaster in modern history.

He told us he's not going to follow those recommendations either.

Turns out Chris has been looking into where this idea came from, hoping to find studies that back it up.

- But there wasn't scientific literature underlying that.

That's kind of what got me started wondering how well that would work out in a real situation.

- With the Cascadia megathrust earthquake likely to hit the Northwest US in the next handful of decades, and the San Andrea's fault keeping Californians worrying about earthquake danger, it's time to figure this out.

So if you're one of nearly half of all US citizens who live in an earthquake prone area, or the millions more globally, watch this episode because not all earthquakes are the same.

Some earthquakes shake violently almost immediately, but others are created by very different forces.

And depending on where you are, they can actually give a warning that you can feel.

We're going to learn how you might identify that warning sign and what Chris plans to do if he's caught in earthquake again.

Stay with us because near the end we list the best and worst buildings to be inside.

And you definitely wanna know if you spend time in one of the worst ones.

(tense music) Okay, first off, magnitude nine earthquakes are the strongest quakes on record.

They're extremely rare, but cause absolute destruction.

Think Sumatra in 2004, Tohoku, Japan in 2011, and the Cascadia megathrust quake that's predicted to hit the Northwest US soon.

They all have something in common in addition to killing tens or hundreds of thousands of people, they are all subduction zone quakes, created when one tectonic plate is forced under another.

That's extremely bad news if you live in a place that is overdue for one of these quakes, like the Pacific Northwest.

But subduction zone earthquakes actually give us a warning because the vibrations they cause travel at different speeds.

- So an earthquake generates about half a dozen different types of waves.

P wave is just a pure pressure wave.

It's like an acoustic pulse traveling through the earth.

It travels a bit faster than all the other types of waves that are generated and it's very light.

You know, it's very light shaking.

- And that means the further away you are from the fault line when the big one hits, the more time between the P waves and the next much more destructive shaking.

- We're not gonna feel the sharp snap and suddenly wind up over there on the ground and go, "How did I get here?"

That's not gonna happen.

What we're gonna feel is this minute of light P wave shaking where we're sitting there going, "Yeah, maybe that's an earthquake."

- And that's crucial time you don't wanna waste because most of the bridges in places like Portland and Seattle will collapse.

Whole neighborhoods and industrial buildings that were built on liquefiable soil will slough into waterways.

Landslides, oil spills, explosions, it's really an apocalyptic scenario.

And what type of building you're in when the big one hits plays a big role in whether or not you survive.

- 1970, 1980 is really when we started understanding how to build structures in high seismic regions.

However, we didn't actually discover the Cascadia subduction zone until 1988.

So really, in Oregon we're concerned about any building that was built before the mid-90s.

- If you exclude wood frame houses, 70% of the built infrastructure in West Coast US cities is not up to modern standards, meaning they might collapse.

But where did this idea of drop, cover, and hold on come from?

- What I found out when I started poking around was that it came from civil defense in the 1950s.

♪ There was a turtle by the name of Bert ♪ ♪ And Bert the turtle was very alert ♪ ♪ When danger threatened him he never got hurt ♪ ♪ He knew just what to do ♪ ♪ He'd duck and cover ♪ - And so we were trained as kids to get under our desks in case of nuclear attack during the Cold War.

And along the way that get under your desk concept was just transferred from nuclear attack to just multi hazard.

So now it's now it's taught universally as the protective action for earthquakes.

- And there has to be like a better way to stay safe during an earthquake.

- In 2011, Chris was at an earthquake conference in an earthquake ready building in Japan when the most recent magnitude nine quake hit.

So he actually got to feel the warning of the P waves.

They were so subtle that the image stabilizer on the camera filming the presentation actually canceled them out.

But then the larger waves hit.

- And then one of the Japanese graduate students said "I think we should go outside."

And we all followed him outside.

So then we watched the building swaying and the flag pole swinging and all of this stuff.

- That was a subduction zone earthquake.

Now let's look at a video of a near crust earthquake.

You can see people start to feel shaking and within a few seconds things are falling off the walls.

Chris told us that if you don't have time to react it's probably a near crust quake and the best action might be to duck and cover.

But what if you do have time?

Most cities in the Northwest US are far back from the coast and the subduction zone, which means they'll be given a warning before the major shaking starts.

- So we're a hundred kilometers back from the subduction zone, which like where I was in Japan, means that I have a I have a full minute of light P wave shaking before the S waves, the damaging waves, get to Corvallis.

So a minimum of about a minute.

And so I started thinking, well, a minute's a long time, and what if the door was right there?

Maybe I should just stroll out the door.

So this one is the the geology building.

That's where my office is now.

It's the typical kind of building that pancake collapses, you know, in an earthquake.

I'm close to the door on the bottom floor and that was on purpose.

So getting out of this one is no problem at all.

I just walk right out.

- And looking at videos of buildings collapsing, it's pretty easy to understand why people choose to evacuate rather than drop, cover, and hold on.

But leaving a building during an earthquake, especially after the P waves hit, is risky too.

- The deciding factor for whether to evacuate or duck, cover, and hold is situational awareness.

First, should you run out of the building or will you just be safer drop, covering, and holding in the building you're already in?

Secondly, where are you running to?

If you're running out of a building into the street where there's a lot of unreinforced mainstream buildings, that could be potentially more dangerous than drop, cover, and hold.

- So how do you decide what you should do?

Well, one of the first parts of situational awareness is knowing what kind of building you're in.

We spoke to Erica about three common building types and how each will fare during an earthquake.

The best case scenario is that an earthquake happens at night because most people will be at home in bed and single families stick-built homes are actually pretty safe.

- They are very flexible.

And so there are very specific details that were concerned about as it pertains to life safety.

Our chimneys, we're concerned about bookshelves, we're concerned about overhead light fixtures that could fall, and we're concerned about porches.

- Because falling objects are the major concern in homes, ducking and covering might be the safest thing to do.

That said, most homes aren't bolted to their foundation.

So while you'll probably survive, your home might not.

Next we have non-ductile concrete buildings.

Ductile means that something is able to deform without losing its strength.

- Concrete is not ductile by nature.

It is very brittle.

It's like glass.

It will fail suddenly.

You'd see crushing of the concrete at the base of our columns.

We would see damage at the joints between our beams and our columns.

- And all that could add up to the building collapsing.

- The most dangerous buildings that we're concerned about are the unreinforced masonry building.

All of the timber framing for the floors are pocketed into the masonry wall.

So there's no mechanical connection.

So as the building shakes back and forth the two will separate.

The wall will fall, usually outwards onto the street.

There's nothing holding up the floors itself and those will collapse.

- And there are a lot of these unreinforced masonry buildings, or URMs for short, in our cities.

Portland has a map of all of its URM's, so make sure to look up your building if you have any doubts.

The safest buildings were built since the mid-90s or have been retrofitted to withstand an earthquake.

- A lot of these modern buildings that are located in high seismic regions are going to perform really well in an earthquake, and we're going to see that people can drop, cover, and hold and not evacuate.

And we are slowly retrofitting our older infrastructure and we've seen in these other earthquakes that those retrofits work.

- So we are in a building that was originally built in the late 1800s and it was originally an unreinforced masonry rebuilding.

But we can tell that this building has been retrofitted because we can see the steel framing members, we can see the steel columns, and beams, and girders, and slab, and metal deck, and we can see the reinforced concrete shear walls that are tied into the existing masonry facade.

So if I'm around when the earthquake happens here in Oregon, this classroom would be a great place to be in.

There's lots of desks to drop, cover, and hold onto for the students and for myself as well as just being in a modern building that has been retrofitted for an earthquake like the Cascadia subduction zone.

- And that's why in countries like Mexico, authorities direct people to evacuate if they are on lower floors of buildings.

And in Israel, newly built schools are teaching duck, cover, and hold on while students in older buildings are being taught to evacuate.

Situational awareness really comes into play if you're on the coast, because there you're not only facing the earthquake which will destroy buildings and bridges just like in cities, but a giant tsunami will follow right behind.

Knowing where high ground is and what obstacles might stand in the way could save your life.

- But I think humans are pretty smart.

We are capable of learning complicated things and learning about what to do in an earthquake is far easier than learning about how to drive a car.

You know, you have to learn how to drive a car properly or you may not survive.

And I think people have to learn how to deal with earthquakes or we may not survive either.

- So what do you think?

Is it worth exploring more complicated messaging that includes situational awareness in our earthquake survival recommendations?

Do you have a plan for when the big one hits?

Let us know in the comments.

And as always, stay safe.

(upbeat music)