JUDY WOODRUFF: And to a very different kind of science story: how researchers in Japan are trying to limit the most catastrophic damage from a tsunami.
NewsHour science correspondent Miles O'Brien files the last of three reports from Japan.
MILES O'BRIEN: Yoshiko Kiuchi (ph) remembers March 11, 2011, as if it were yesterday.
"We got a warning that tsunami would come in two minutes," she told me. "So, we escaped by car in a rush, literally with little more than the clothes on our back."
Her home and her neighborhood in the coastal town of Arahama are gone, pressure-washed by the epic tsunami. She lives in temporary housing now, but comes back here regularly to gather what she can out of what remains of her garden.
"I will take these flowers to my temporary house," she said. "I will plant them in the planter there."
Nearby, there is plenty of evidence the Japanese are working hard to clean up and rebuild. But how? The tsunami, not the earthquake, is linked to nearly all the 20,000 deaths here. And building coastal towns that can repel giant waves is not easy or cheap.
That is what they are working on here at the Port and Airport Research Institute about fifty miles south of Tokyo. It was open house day when we were here, a chance for people to see and feel how powerful even a scaled-down version of a tsunami can be. But it is not just for show.
TARO ARIKAWA, marine engineer: All right, go.
MILES O'BRIEN: Taro Arikawa is an engineer here. When he is not drenching the public, he is working on a pneumatic breakwater system, hollow steel pylons buried in the seafloor that telescope when air is pumped in.
How quickly do they come up?
TARO ARIKAWA: Three minutes.
MILES O'BRIEN: Wow.
In Wakayama Harbor, they tested the idea in rough seas. Once they popped above the surface, the pylons reduced the size of the waves by half.
So it is possible to conceive of someday a tsunami barrier for Japan?
TARO ARIKAWA: Yes, maybe.
MILES O'BRIEN: Really?
TARO ARIKAWA: And I will -- I will continue to study the purpose, withstand the tsunami. So, I -- we will succeed to construct the tsunami barrier for the future.
MILES O'BRIEN: But at no small cost. Arikawa says a system to protect the entire harbor would cost 10 billion yen, or $130 million, but it might be worth the money.
Coastal engineering professor Akio Okayasu is working on tsunami protection ideas at the Tokyo University of Marine Science and Technology. He is creating a detailed database of the inundation from the great tsunami using volunteers to chart the flotsam from the high water marks up and down the east coast of Japan. With 5,000 readings and counting, he has found some clear-cut evidence that breakwaters do indeed work.
Kamaishi Bay was protected with a breakwater that apparently reduced the wave height by nearly two-thirds.
AKIO OKAYASU, Tokyo University of Marine Science and Technology: We believe it did help reduce the height of the tsunami inside of the bay.
MILES O'BRIEN: It took a little bit of the power out of it?
AKIO OKAYASU: Yes, we say energy.
MILES O'BRIEN: But he says breakwaters and seawalls are just part of a system. After all, they cannot build a huge concrete wall all around Japan. The system, says Professor Okayasu, must include the people.
AKIO OKAYASU: If the people don't evacuate, the system doesn't work anyway. So we need to prepare. How can we make the people feel easy to evacuate?
MILES O'BRIEN: That is what they are studying here at Oregon State University's Hinsdale Wave Lab.
Dan Cox is the director.
DAN COX, Hinsdale Wave Research Laboratory, Oregon State University: One thing that our research is looking at is the role of vertical evacuation. So this means going up into a building or onto an earthen mound that is still within the inundation zone, still -- you're still going to be in the flooded zone, but you are much safer just by going up.
MILES O'BRIEN: They created a scale model of Seaside, Ore., population 6,400, watched what happened when big waves rolled in, then fed the data into a computer model.
DAN COX: And the current strategy is only to go up into the hills.
MILES O'BRIEN: And if everyone in Seaside did that, Cox predicts 1,700 people would perish because they would be unable to get to high ground in time.
DAN COX: But if we adopt the strategy of vertical evacuation, then those numbers could change.
MILES O'BRIEN: If the town had some strategically located earthquake and wave-hardened towers in the inundation zone, the predicted casualty count drops to 200. Cox believes it is time to write a tsunami building code in Oregon that embraces vertical evacuation.
DAN COX: Part of it could be either retrofitting old buildings. So, it still has to withstand the earthquake from the subduction zone. And it could be building new buildings that are specifically purposed for vertical evacuation. Or it could be modifying plans for future buildings.
MILES O'BRIEN: Ten miles south of Seaside, in the town of Cannon Beach, they want to do just that. The $4 million city hall they would like to build would double as a tsunami evacuation building.
In Japan, they have about a dozen vertical evacuation structures in tsunami zones. And they have invested much time and money into ensuring their high-rise buildings do not fall during an earthquake. I went to the place they call E-Defense outside Kobe. It is home to the largest seismic shake table in the world.
Engineer Takuya Nagae gave me a fascinating tour deep in the bowels of this massive $400 million facility.
TAKUYA NAGAE, seismic engineer: Twelve pistons support vertically, and five pistons, you know, moves horizontally for each direction.
MILES O'BRIEN: During my visit, they were getting ready for another test. About once a month, big structures are built, furnished and then shaken violently to see what happens.
TAKUYA NAGAE: We have to break that specimen to find the capacity, not just, oh, it's safe, so we can stop. No, we have to continue to see the real capacity.
MILES O'BRIEN: Nagae showed me a stark example of what they have learned here. This reinforced concrete school building failed during its shake test, but this one fared much better. It had been retrofitted with steel beams.
TAKUYA NAGAE: So we have to promote retrofitting as much as possible. And we have to enhance the seismic capacity of cities. And it's very important to retrofit all type of buildings designed by old code.
MILES O'BRIEN: But there is another code here, one that is etched in stone, which I saw in the remote fishing village of Aneyoshi.
The warning on the stone is clear. It says don't build your homes below this point. As matter of fact, high water mark for this latest tsunami is about 300 feet down this road. These stones -- and there are hundreds of them all throughout Japan -- are warnings from the ancestors, letting people know and reminding them of the force of nature. Mostly, they are ignored or forgotten. In this case, this town listened.
No one in this town built a home below the old stone after the last big tsunami in 1933.
Teruo Kimura (ph) was born in this house and now watches his grandchildren play in the driveway.
"Before the tsunami, villagers were living on the shore," he told me. "Because the houses were all washed out, villagers built their houses along this street. So, we are lucky to have houses up here. I haven't heard anyone want to live down there."
Of course, Aneyoshi is the exception. People in Japan will return to their homes in the lowlands by the sea, but not Yoshiko Kiuchi (ph). She lost too many friends and neighbors. Her garden, her flowers represent a good memory, but not a longing to return.
"No, I was living a happy life," she said. "This was a very beautiful place. I do not want to live here anymore."
For many here, no amount of engineering will be enough to wall off the sadness and the fear.
JEFFREY BROWN: It's Science Thursday on our website.
You will find Hari Sreenivasan's interview there with a chemistry professor who writes poems about thermodynamics, kinetics and atomic reactions. You will also -- you also can watch Miles' previous stories from Japan.