TOPICS > Science

After Haiti Quake, Using Science to Build Sturdier Buildings

January 11, 2011 at 12:00 AM EST
Loading the player...
As Haiti recovers from the devastating earthquake that flattened Port-au-Prince one year ago, researchers are examining how the country can lessen the damage from another disaster using building science. Science correspondent Miles O'Brien reports.

TRANSCRIPT

JUDY WOODRUFF: Next, making buildings sturdier so they can withstand the force of an earthquake.

Tomorrow marks a year since Haiti’s devastating earthquake.

As we continue our series of reports about Haiti, NewsHour science correspondent Miles O’Brien looks at what researchers are doing to lessen the fallout from another disaster.

MILES O’BRIEN: When the ground shook beneath Port-au-Prince a year ago, structural engineer Kit Miyamoto dropped everything. And, in three days, he and his team were in Haiti trying to figure out what they could do to help.

KIT MIYAMOTO, structural engineer: It’s like almost kind of like a war zone here, isn’t it? It’s like a World War II movie here.

MILES O’BRIEN: The magnitude-7 earthquake destroyed a quarter-million homes, leaving a million people homeless — 300,000 were injured, 230,000 killed. The World War II analogy persists.

KIT MIYAMOTO: Just put in perspective, nuclear blast in Hiroshima killed 200,000 people, right, and it took the Japanese government 10, 20 years to really rebuild Hiroshima.

MILES O’BRIEN: From Japan originally, Miyamoto came to California as a teen and has been in the business of designing and retrofitting buildings to better withstand earthquakes for 20 years. We met at his most famous retrofit project, the flying saucer-like Theme Building in the middle of Los Angeles International Airport.

As an engineer, someone who has committed his life to making structures safe and earthquake-hardy, if you will, when you see that, what goes through your mind?

KIT MIYAMOTO: Oh, just incredible, because we knew there’s a risk there. All the engineers knew that. And, also, the engineers knew about how to repair those and fix, strengthen those buildings before the earthquake.

MILES O’BRIEN: Purdue University seismologist Eric Calais also came to Haiti a few days after the quake to gather some data. His efforts are featured in the new PBS NOVA program Deadliest Earthquakes.

ERIC CALAIS, seismologist, Purdue University: So, this whole area here has moved 30 centimeters to the east during that earthquake.

MILES O’BRIEN: Since 2003, Calais and his team have measured the movement of the fault that fractured beneath Port-au-Prince. As he watched the slow-motion collision of the Caribbean and North American tectonic plates, he knew a big quake was inevitable.

ERIC CALAIS: The last earthquake on that fault occurred about 250 years ago. And it’s building up elastic energy at seven millimeters per year. Seven times 250 is about 1.8 meters.

MILES O’BRIEN: One-point-eight meters, or six feet, of stored strain equates to the energy of about 100 Hiroshima bombs. In 2008, Calais foresaw a magnitude-7 earthquake.

ERIC CALAIS: What we saw was a fault being loaded just like a rubber band.

MILES O’BRIEN: He knew it would snap, but he could not say when.

ERIC CALAIS: We cannot predict earthquakes. We had no way of telling whether it was going to be today, tomorrow, in 10 years, in 100 years. So, we did not put a day on it. And it’s not that we were afraid to put a date on it. It’s that, as a scientist, we can’t.

MILES O’BRIEN: So, saving lives is more about keeping buildings intact than early warning. Structural engineers have learned a lot about this over the years by shaking buildings to see how they might fail.

I got a firsthand taste of the technique on the roof of the Millikan Library at the California Institute of Technology. Flip the switch, let the heavy disk spin, and the building starts swaying.

Holy cow. Wow. It’s an artificial earthquake. And it’s all for the good of science and good engineering, for real.

So, could you shake this building even more than this? Is that possible?

MAN: I guess like, for …

MILES O’BRIEN: Yes.

MAN: … the maximum is this amount.

MILES O’BRIEN: This is it? But you really get sense of the swaying.

Engineering seismology professor Tom Heaton presides over the shaking, not to torment the studying students below, but to understand the building’s frequency.

TOM HEATON, California Institute of Technology: So, this type of motion tells us how the building dances around an earthquake. So, for a tall building, a tall building tends to vibrate at some natural frequency, almost as if you were looking at a slow-motion picture of some sort of tuning fork that’s vibrating at some pitch.

And so, if you excite the building at the natural pitch of the building, the vibration just gets bigger and bigger.

MILES O’BRIEN: This is what happened in Mexico City during the devastating magnitude-8 earthquake of 1985. The ground didn’t move violently, but the tremor lasted a minute-and-a-half, and its frequency was just right to make the tall buildings sway more and more, until they toppled.

TOM HEATON: All the highly engineered, very well-constructed buildings were the tall buildings, which were the ones that actually collapsed. And the reason was because the ground motion was tuned to the tall buildings.

MILES O’BRIEN: So, earthquake engineers spend a lot of time thinking of clever ways to reduce the swaying.

Back at the LAX Theme Building, Kit Miyamoto and I slithered our way inside the $10 million system he designed to help the 50-year-old icon ride out a magnitude-7 earthquake.

Well, obviously, I’m not in the observation deck here. Below me is the building. Above me is 1.2 million pounds of steel equivalent to the weight of two 747s — attaching the two, eight of these giant dampers, shock absorbers, if you will. Here is how it’s supposed to work. There’s an earthquake. The building moves this way. The steel above goes that way. It’s a giant counterweight.

KIT MIYAMOTO: Having that, it reduced the motion of the structure to four inch to about two inch.

MILES O’BRIEN: But the engineering and the systems that allow building to withstand tremors do not have to be as elaborate as this.

LUCY JONES, seismologist, U.S. Geological Survey: This is the Church of the Angels in Pasadena, California.

MILES O’BRIEN: Yes. Yes.

LUCY JONES: The church was built in 1889.

I met veteran U.S. Geological Survey seismologist Lucy Jones at her church in Pasadena. In 1889, a rock and mortar wall supporting a roof probably seemed like a good idea. But it is the worst possible construction technique in an earthquake zone. In fact, it was outlawed here for new construction in 1933.

LUCY JONES: What an earthquake is, is shaking. It’s forces, just like gravity, but now they’re pushing sideways, instead of up and down.

MILES O’BRIEN: So, sideways gravity, we don’t build for, typically?

LUCY JONES: We don’t typically build for sideways gravity, but that’s exactly what you need to do for an earthquake.

MILES O’BRIEN: The church lost its bell tower during the big quake in 1971. And, more recently, Lucy Jones made sure her fellow parishioners knew how vulnerable it was to even more damage. So, they fixed it. The basic idea, make sure the roof wouldn’t have to rely on the masonry walls to stay standing.

LUCY JONES: The way this was done is that steel beams were put down through the stone walls, and then the roof was tied to those steel beams. And then, inside, we also have structural members to hold the roof together, and so that, even if all of the mortar dissolves, and the rock starts coming down, the roof should still stay up.

MILES O’BRIEN: But retrofitting a well-endowed church or a well-known landmark may seem like a luxury Haitians cannot afford. Or is it?

People see this elaborate system that you built have here, $10 million, and they think, well, it’s too expensive to build a building that will ride out a 7.0 earthquake, and certainly place like Port-au-Prince, Haiti, they can’t afford to do it. Is that true or false?

KIT MIYAMOTO: It’s a false. For example, right now, there are over 100,000 buildings being damaged, and we are spending about, average, $1,000 per house to not only repairing it, but also to provide the seismic strengthening at the same time.

MILES O’BRIEN: Engineers say it is more about mind-set than money. Three months after Port-au-Prince was devastated, a quake of the same magnitude struck a city of similar size and means, Mexicali, Mexico. But only a handful died.

Here, they are more attuned to the threat of earthquakes and distribute simple instructions on how to build with that in mind, like using rebar and metal straps, which were not commonly used in Haiti.

KIT MIYAMOTO: So far, our experience is good. You guys are good engineers. I noticed that.

MILES O’BRIEN: Kit Miyamoto is trying to spur Haitian engineers and builders to think differently.

MAN: We start coming, applying new techniques, OK, and just to reinforce the wall and build them in the best way that they will not be — fall.

MILES O’BRIEN: Still, one year later, there are few obvious signs of rebuilding of any kind. But Kit Miyamoto remains optimistic.

KIT MIYAMOTO: It seems like nothing going on for a whole 12 months, because such a chaos and such a mess, you know? But, as you can see, that there is the — we understand what happened. We understand how to fix it. And we understand that — how Haitian people can repair and engineering to fix those things together.

MILES O’BRIEN: Block by reinforced block, it appears they are building better here, haunted by a natural disaster that was so much worse than it had to be.

JUDY WOODRUFF: NOVA’s program Deadliest Earthquakes airs tonight on most PBS stations.