Unearthing Proof of a Tsunami in the Northwest The threat posed to coastal areas by tsunami flooding gained new attention after the Indian Ocean catastrophe that killed 200,000. Now scientists say a huge tsunami hit the Pacific Northwest in 1700 -- and it may happen again.
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Unearthing Proof of a Tsunami in the Northwest

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Unearthing Proof of a Tsunami in the Northwest

Unearthing Proof of a Tsunami in the Northwest

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The World Health Organization holds a conference in Thailand this week on the Indian Ocean tsunami that killed 220,000 people last December. The conference will focus on emergency response to the disaster and how officials can be better prepared in the future. Half a world away, Americans are asking these same questions.

(Soundbite of people at town meeting)

MONTAGNE: About 70 people have gathered for a town meeting in a small community called Tokeland on the southern edge of Washington state. That's an impressive turnout considering fewer than 200 people live in Tokeland, a narrow finger of a peninsula that juts out into Willapa Bay on the Pacific Coast. Willapa Bay is adjacent to the Cascadia subduction zone. That's a vast underwater fault that runs from British Columbia to California. Nobody here thought much about tsunamis until the Indian Ocean disaster.

Ms. STEPHANIE FRITTS (Pacific County Emergency Management Agency): OK. I'm Stephanie Fritts. I'm with the Pacific County Emergency Management Agency. It covers all the...

MONTAGNE: Stephanie Fritts' job is to tell people what to do in an emergency. This night, she's joined by a group of scientists who say that tsunamis as powerful as the one that struck in the Indian Ocean have hit Tokeland in the past. They're certain the community will get hit again, they just can't predict when. The crowd becomes restless as Stephanie Fritts outlines the state's plan.

Ms. FRITTS: We've adopted a philosophy of some personal responsibility within neighborhoods and communities like Tokeland when we first placed...

Unidentified Man: It seems to me you're glossing over completely a warning system.

Ms. FRITTS: I haven't gotten to that issue yet, but I will.

MONTAGNE: There are many questions from the crowd: How much warning time will we have? How deep will the water be? Scientists are trying to get more information from places like this.

(Soundbite of wave)

MONTAGNE: The Newaukum River is a sleepy winding stream really of water that feeds Willapa Bay. When the tide is low early in the morning, the banks of the river are exposed and they reveal a violent past.

Mr. BRIAN ATWATER (Geologist; US Geological Survey): This is the wonderful thing about working at this very sheltered place, because anything dramatic shows up.

MONTAGNE: Brian Atwater has made many dramatic discoveries here on the Newaukum. He's a geologist with the US Geological Survey. Today, he's leading a group of scientists and students in canoes. He points out the scars left behind by earthquakes and tsunamis past, the sheer power of which seemed inconceivable until last year and the Indian Ocean tsunami.

Mr. ATWATER: I'm just going to land against the current here.

MONTAGNE: All right.

Brian Atwater docks our canoe in an area where tree roots poke through the low walls of the riverbank. These roots are evidence of ghost forest, ancient trees that used to grow here until powerful earthquakes buckled the Earth, dropping land and trees below sea level. Saltwater from the Pacific flowed in, eventually killing the forest. He wields a small hand shovel to scrape away the surface of the riverbank.

Mr. ATWATER: There you have the soil that the tree roots are in, right?


Mr. ATWATER: And then above it, gray mud. The land dropped and the mud came in. It was carrying leaves. These are from a tree from about AD 400, the year 400.

MONTAGNE: That leaf we're looking at?

Mr. ATWATER: Yeah.

MONTAGNE: It looks fresh as a fresh leaf.

Mr. ATWATER: Sure. Sure.

MONTAGNE: I'll be darn.

Mr. ATWATER: So it has something to do with land being buried quickly by tide flat mud and that mud protecting the buried soil. So that gives you some idea that you went from a forest to a bare tide flat.

MONTAGNE: To go from a forest to these tidal flats, the land would have had to suddenly drop about three to six feet. Further down the river, Brian Atwater hacks away at a wall of gray mud and reveals one of his most remarkable discoveries.

(Soundbite of shoveling)

Mr. ATWATER: Now another thing that shows up here is the start of evidence of the tsunami. Can you see it?

MONTAGNE: That little thin black-gray line?

Mr. ATWATER: That's right, running along the base.

MONTAGNE: That dark gray line is only as wide as a finger. It's made of beach sand washed inland by a powerful tsunami, a tsunami that struck before any written records were kept in the Pacific Northwest. Brian Atwater combines science and some detective work to figure out exactly when the tsunami hit. After carbon dating put the event somewhere around 1700, he contacted scientists in a place that would have had written records during that time: Japan. Sure enough, Japanese researchers had accounts of an orphan tsunami, a tsunami that hit the Japanese coast without anyone feeling the tremors of an earthquake. They concluded that the tsunami was triggered by a powerful earthquake off the coast of Washington and they were able to pinpoint the exact date that Brian Atwater's line of sand appeared.

Mr. ATWATER: At this position here, you're in the evening of the 26th of January, a Tuesday, 1700.

MONTAGNE: The exact time: 9 PM. Scientists cannot be as precise about what happened to the native people who lived along the river back then, but there are clues.

Mr. ALEX BORDEAU (Archaeologist): That's beautiful. See how that rock is bright red? That's because it was so hot.

MONTAGNE: Hot meaning fire. Archaeologist Alex Bordeau has dug out from the riverbank something called a fire-cracked rock, a rock that would have been used in fires made along these banks by Native Americans who used this site for hundreds of years.

Mr. BORDEAU: Fire-cracked rocks, I think, tell us this particular site was something where some very important things were going on.

MONTAGNE: Archaeologists believe this site was used by Native-American fishermen. There are fragments of baskets and fish bones preserved in the riverbank. Just above those remains, the thin gray line of beach sand, evidence that this site was wiped out by the tsunami in 1700. But were the people wiped out as well?

Mr. BORDEAU: We don't know.

Mr. ATWATER: They had high ground.

MONTAGNE: The people could have...

Mr. BORDEAU: Yeah, they could get away in a big hurry. Clearly, these people here would have felt the earthquake more than likely.

MONTAGNE: Everyone here agrees that Indian fishing sites like this one typically were used only in the spring and summer. The tsunami hit in January. These days, of course, people live in Tokeland all year round. They've always known earthquakes are a possibility, but even scientists were skeptical the Cascadia Subduction Zone could create an earthquake powerful enough to trigger a tsunami.

Mr. ATWATER: Twenty years ago, most scientists would have laughed at the idea. Through the '70s, the Subduction Zone was thought to be locked up permanently so that it couldn't produce very big earthquakes. Then in the early '80s, geophysicists said maybe it can produce very big earthquakes. In the late '80s, geologists found out that it had.

MONTAGNE: Brian Atwater's research shows just how extensive damage from tsunamis triggered by such earthquakes could be. His findings, along with the work of other geologists, are being used to created inundation maps that show how much land would be flooded by a tsunami. Washington state is using the maps to help formulate emergency plans. One result, a common site along coastal roads nowadays are blue and white signs depicting a giant curling wave chasing a silhouetted figure up a hill to higher ground. The words above: `Tsunami Hazard Zone.'

You can see snapshots of our trip with geologist Brian Atwater down the Newaukum River at npr.org.

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