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♪ [ominous theme music]

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(male narrator) Boxing Day, 2004.

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The world was shocked

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by one of the worst natural[br]disasters of all time.

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Over 250,000 people died.

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The cause of this devastation

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was the most powerful kind[br]of earthquake on the planet,

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called a mega thrust.

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This event made us realize[br]how poorly prepared we are

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to face these huge geological catastrophes.

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And scientists are now[br]trying to work out

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where else is at risk.

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They have discovered

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that a megathrust as large[br]as the Sumatra quake

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could hit North America.

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♪ [music playing]

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Everyone knows that America[br]is going to be struck

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by a devastating earthquake.

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For years, the people of California[br]have been waiting for the day

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when the San Andreas Fault[br]unleashes the big one.

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But all the time

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an even more powerful hazard[br]has lain undiscovered.

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A giant megathrust earthquake[br]just like the one that hit Indonesia

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threatens America's Pacific Northwest.

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A huge area from northern California

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all the way to Canada is at risk,

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including major cities[br]like Seattle and Vancouver.

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(scientist) It's a major earthquake.

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(emergency worker) We were just[br]coordinating

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an emergency response that's going out.

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(narrator) The authorities have[br]started to prepare for this catastrophe.

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Rehearsals like this one help[br]to train the emergency services

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to deal with such an event.

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[screaming]

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(narrator) Children are now[br]being taught lessons in survival

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that could mean the difference[br]between life and death.

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The source of all this danger,

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lying underwater off[br]the Pacific Northwest coast,

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is a huge gash in the earth's crust,

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a subduction zone.

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The earth's crust is made up[br]of huge plates of rock

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that are constantly in motion.

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Where two of these giant[br]plates meet head to head,

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one of them can get pushed[br]down under the other.

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This is a subduction zone.

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It was a subduction zone[br]off the coast of Sumatra

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that caused the Boxing Day earthquake.

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And worldwide there are[br]many other similar faults.

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(Prof. Bill McGuire) There are[br]subduction zones all over the planet,

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but mainly they occur[br]around the rim of the Pacific,

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the so-called "Ring of Fire" and[br]lots of big earthquake occur there,

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most of the world's really[br]destructive earthquakes.

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(narrator) Subduction zones[br]cause earthquakes

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when the plate that's being[br]pushed down gets stuck.

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As it pushes, the upper plate[br]gets squeezed and distorted.

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Eventually the strain becomes too much.

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The upper plate slips creating[br]a megathrust earthquake.

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(Tim Walsh) A megathrust earthquake[br]happens when the subducting slab,

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which is diving under[br]the overriding plate,

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is locked and causes the overriding[br]plate to bulge upward.

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And then when that becomes unlocked,

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it slides suddenly creating[br]a huge earthquake.

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Worldwide, these are[br]the biggest earthquakes.

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They range in magnitude[br]up to nine and a half.

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(Prof. Bill McGuire) Generally speaking,[br]if you have two great masses of rock

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and you're scraping them,

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one underneath the other,

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they're not going to move very easily

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and you're going to get [br]a lot of friction there.

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And I liken it to sort of two cheese[br]graters pushing past one another,

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very, very difficult to get any[br]smooth sort of movement there.

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(narrator) But as the 26th[br]of December showed,

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megathrust earthquakes have[br]another devastating consequence.

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(Prof. McGuire) In the case[br]of a megathrust earthquake,

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the overlying plate,

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which has been bent,

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pins back upwards into position.

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And it's that sort of pinning motion

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that transmits an enormous amount[br]of energy to the sea bed.

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That energy is then transmitted[br]to the water above it

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which oscillates up and down

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and then moves out [br]as a series of huge ripples.

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And that, in a sense, [br]is what a tsunami is.

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(narrator) A tsunami is very[br]different from a normal wave.

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In normal waves, only the water[br]on the surface is moving.

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But a tsunami involves the movement[br]of the whole water column,

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millions of tons of water.

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(Prof. McGuire) Normal wind driven[br]waves have very small wavelengths,

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that's from crest to crest.

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So it maybe a few tens of meters

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and the wave has crashed[br]and it's gone.

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Tsunami have a wavelength that[br]could be hundreds of kilometers long.

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So when that initial wave comes in,

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the water behind it is pretty much [br]at the same level.

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And that can keep coming for five[br]or ten minutes as a huge flood.

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And that's why they're so destructive.

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It's not a simple wave that you can[br]hold your breath under and survive.

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(narrator) The combination of[br]massive earthquakes and tsunamis

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makes subduction zones[br]a deadly geological hazard.

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And so it should have been[br]a cause for concern

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that the Cascadia subduction zone,

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a 600 mile long fault,

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lies right off the Pacific Northwest coast.

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The strange thing was [br]Cascadia didn't seem to be a danger at all.

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For years, scientists have been[br]monitoring seismic activity

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along the Cascadia subduction zone.

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They found that unlike[br]other subduction zones,

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it was virtually silent.

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(Robert) People saw that Cascadia had[br]many of the features of a subduction zone.

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It had an oceanic trench.

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It had a line of volcanoes[br]above the subduction zone.

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It simply didn't seem to[br]have big earthquakes

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and so they put it in a category of its own,

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the subduction zone that[br]doesn't have big earthquakes.

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(narrator) And there was[br]a simple explanation

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for why Cascadia wasn't creating earthquakes.

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If the plates were moving[br]smoothly past each other,

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there would be no strain being built up[br]and no earthquakes.

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♪ [music playing]

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This theory was backed up by[br]over 200 years of historical record.

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For as long as the Europeans[br]have lived here,

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there's no record of any significant[br]earthquakes from Cascadia.

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But in this region,

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there is another kind of history,

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a kind that isn't written down.

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For centuries before the Europeans arrived,

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this land was home to native peoples.

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Viola Riebe is a member of the Ho nation[br]on the northern Washington coast.

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As a child she was taught the legend[br]of the Thunderbird.

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(Viola Riebe) The Thunderbird[br]lives in the glacier

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at the headwaters of the Ho River.

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When he comes out,

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the ground would start to shake

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and he would even make[br]the waters troubled.

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(narrator) Could this legend[br]be describing a real event,

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a megathrust earthquake[br]that occurred long ago?

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Most geologists have no time[br]for such speculation.

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But one decided to take a closer look.

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♪ [guitar music]

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(narrator) Brian Atwater wondered whether[br]the native legends might be a warning

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that the Pacific Northwest could[br]be at risk from giant earthquakes.

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So he took to his canoe

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and started exploring the marshes[br]and rivers of the Washington coast.

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He was hoping that[br]the layers of mud here,

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laid down over centuries

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might provide a clue[br]to the events of the past.

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And buried in the marsh,

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he did find evidence[br]of an unusual event.

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(Brian Atwater) We're on[br]an ordinary coast,

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standing on a salt marsh like this one.

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Underneath we find salt marsh deposits,

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salt marsh deposits,

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salt marsh deposits,

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just steadily on.

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But here we have something[br]completely different.

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We've got a spruce forest here,

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underneath the salt marsh.

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We can dig out here

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the bark,

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the bark of Cyprus spruce.

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(narrator) These trees can[br]only grow on dry land.

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Yet this layer of trees[br]was covered with mud

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that must have been deposited by water.

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So the land here must once have been[br]higher and then at some point,

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it dropped down,

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plunging the forest underwater.

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(Brian Atwater) At the time that[br]the spruce forest dropped down,

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sand was laid down.

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It's the first thing that covers[br]the peat is a little skin of sand.

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So that's the mystery.[br]How did that happen?

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(narrator) Since there's no sand nearby,

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there must have been [br]a sudden rush of seawater

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that carried the sand in with it.

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This was no gradual change in land level.

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It must have been a violent collapse.

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(Brian Atwater) The easiest[br]explanation for that

0:11:24.480,0:11:26.960
is that you had an earthquake

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that caused the land here to drop

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and also warped the sea floor.

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That warping of the sea floor set off a tsunami,

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and the tsunami then lays down the sand

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on the freshly down-dropped land surface.

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(narrator) Carbon dating[br]of the buried trees

0:11:45.840,0:11:50.800
showed that this event had occurred[br]roughly 300 years ago,

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before Europeans had arrived.

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So the native legends might[br]indeed be about a real event.

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But it would need more than[br]just layers of mud

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to prove that there had been[br]a devastating earthquake here.

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The next piece of evidence was to[br]come from thousands of miles away.

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As the Indonesia earthquake has shown,

0:12:29.240,0:12:33.200
megathrust earthquakes cause [br]damage at astonishing distances

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because they create tsunamis.

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If such an earthquake really[br]had occurred in Cascadia,

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it should have created a tsunami capable[br]of traveling right across the Pacific

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to countries like Japan.

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Kenji Satake is a geologist who[br]studies earthquakes and tsunamis.

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When Satake heard about[br]Brian Atwater's theory,

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he realized Japan could hold the answer.

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(Kenji Satake) 300 years ago[br]is prehistoric time for Americans,

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but in Japan, we have documents

0:13:19.800,0:13:25.680
that would record the tsunami[br]from Cascadia 300 years ago.

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So that's why we started[br]looking for the records.

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(narrator) What Satake was looking for

0:13:32.280,0:13:36.840
was a very special kind of tsunami.

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Most tsunamis in Japan are[br]caused by nearby earthquakes,

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so they're accompanied[br]by shaking of the ground.

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But a few tsunamis arrive[br]without shaking

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because the parent earthquake is far away.

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When there's no known earthquake[br]that could have caused the wave,

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it's called an orphan tsunami.

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So Satake started hunting for[br]records of an orphan tsunami

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that could have come[br]from the Pacific Northwest.

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And in the coastal town of Miho,[br]southwest of Tokyo,

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there's a document that[br]describes just such a tsunami.

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(Kenji Satake) This page describes[br]a tsunami on January 28th of 1700.

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On that day, from morning,[br]tsunami arrived at this town,

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like a high tide,

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and the receding wave was like big river

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and it continued seven times[br]until the noon of that day.

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(narrator) The account told how[br]the villagers took refuge in a shrine

0:14:57.160,0:15:01.920
that still exists today.

0:15:01.920,0:15:03.760
The author also recorded

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that this tsunami was unlike any[br]that he had experienced before.

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(Kenji Satake) Writer note that[br]there was no earthquake

0:15:14.080,0:15:15.480
but the tsunami arrived.

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So he was surprised.

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And he said such a strange thing

0:15:19.720,0:15:24.640
should be passed [br]to the future generation.

0:15:24.640,0:15:28.880
(narrator) Crucially, the same tsunami[br]was recorded in four other accounts

0:15:28.880,0:15:31.960
from different parts of Japan.

0:15:31.960,0:15:36.160
So this couldn't be a local event.

0:15:36.160,0:15:37.560
Satake thought this tsunami

0:15:37.560,0:15:41.240
might indeed have come from[br]a huge megathrust earthquake

0:15:41.240,0:15:44.480
5000 miles away in Cascadia.

0:15:49.000,0:15:50.520
But still there was no proof

0:15:50.520,0:15:53.840
that the tsunami had come [br]from North America.

0:15:53.840,0:15:55.800
The carbon dating only showed that

0:15:55.800,0:15:59.440
the Cascadia event had happened [br]at roughly the same time

0:15:59.440,0:16:01.080
as the orphan tsunami.

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The final piece of evidence would[br]be found in a mysterious corner

0:16:08.000,0:16:10.360
of the Pacific Northwest.

0:16:20.800,0:16:23.400
A hundred miles southwest of Seattle,

0:16:23.400,0:16:26.360
in a remote area of the Washington coast,

0:16:26.360,0:16:29.360
is the ghost forest.

0:16:29.360,0:16:32.720
These are trees that died[br]hundreds of years ago

0:16:32.720,0:16:36.720
that remain standing to this day.

0:16:36.720,0:16:37.800
(David Yumaguchi) Sometime in the past,

0:16:37.800,0:16:42.200
this would have been an[br]in intact red cedar forest,

0:16:42.200,0:16:46.680
large trees standing 100 feet[br]or more in the air

0:16:46.680,0:16:50.760
and this landscape was filled with them

0:16:50.760,0:16:55.280
and then one day, something[br]killed the trees here in place.

0:16:55.280,0:16:59.120
And the mystery is,[br]"What killed them?"

0:16:59.120,0:17:02.880
you know, what could kill an entire forest

0:17:02.880,0:17:08.520
along 60 miles of Washington coast[br]just like this?

0:17:08.520,0:17:11.400
[chainsaw starts up]

0:17:11.400,0:17:14.480
(narrator) Tree specialist David[br]Yumaguchi has spent years

0:17:14.480,0:17:19.440
trying to solve the mystery of[br]what happened to the trees.

0:17:19.440,0:17:22.200
He wanted to work out[br]when they had died

0:17:22.200,0:17:23.960
by looking at their tree rings.

0:17:26.839,0:17:29.320
(David Yumaguchi) Most people[br]know that trees have annual rings.

0:17:29.320,0:17:32.280
So depending on the climate[br]from year to year,

0:17:32.280,0:17:36.720
the tree rings are either wide[br]or narrow or wide or narrow.

0:17:36.720,0:17:40.640
And so the developing of bar code[br]going back in time,

0:17:40.640,0:17:42.920
it's unique in time.

0:17:42.920,0:17:44.680
(narrator) Using this pattern,

0:17:44.680,0:17:49.440
David was able to work out exactly [br]when the trees had died.

0:17:49.440,0:17:51.720
And he found out that all of them

0:17:51.720,0:17:56.560
had died around the early months of 1700.

0:18:05.320,0:18:09.360
(David Yumaguchi) The summer[br]before the tsunami hit Japan,

0:18:09.360,0:18:12.360
these trees were just growing[br]happily in the forest here.

0:18:12.360,0:18:14.200
Then the winter came along

0:18:14.200,0:18:15.880
and by the following summer,

0:18:15.880,0:18:17.920
they were all dead.

0:18:17.920,0:18:24.040
And so the tree ring story matched[br]the Japanese tsunami records perfectly.

0:18:28.360,0:18:29.840
(narrator) There was now no doubt

0:18:29.840,0:18:33.120
that the same catastrophe [br]that had killed the ghost forest

0:18:33.120,0:18:37.080
had also sent the tsunami across to Japan.

0:18:37.080,0:18:39.240
And from the Japanese records,

0:18:39.240,0:18:44.080
Kenji Satake could work out exactly [br]when it had happened,

0:18:44.080,0:18:52.440
on the 26th of January, 1700, at 9 p.m.

0:18:52.440,0:18:54.080
On that winter's night,

0:18:54.080,0:18:59.360
a megathrust earthquake just like[br]the Boxing Day earthquake of 2004,

0:18:59.360,0:19:04.320
struck the Pacific Northwest.

0:19:04.320,0:19:09.600
It drowned forests[br]and turned land into sea.

0:19:09.600,0:19:13.400
It sent a tsunami hurtling[br]across the Pacific.

0:19:13.400,0:19:15.520
And it spawned a legend

0:19:15.520,0:19:19.400
that would be passed down[br]to a dozen generations.

0:19:27.360,0:19:31.240
The scientists knew that[br]if it had happened here once,

0:19:31.240,0:19:34.520
it would happen again.

0:19:34.520,0:19:41.320
One day the people of the Pacific[br]Northwest will face a megathrust earthquake.

0:19:41.320,0:19:44.000
So how big will it be?

0:19:44.000,0:19:47.600
What damage will it cause?

0:19:47.600,0:19:49.440
And when will it happen?

0:19:56.480,0:20:01.240
The first question is, [br]"How large will the earthquake be?"

0:20:01.240,0:20:05.960
The power of an earthquake depends[br]on the size of the fault that breaks.

0:20:05.960,0:20:08.480
In the case of the Boxing Day earthquake,

0:20:08.480,0:20:10.840
it was huge,

0:20:10.840,0:20:15.440
over 600 miles of fault ruptured.

0:20:15.440,0:20:20.280
The Cascadia subduction zone [br]is almost exactly the same length.

0:20:20.280,0:20:25.880
So it's likely that it will create[br]an equally powerful earthquake.

0:20:25.880,0:20:26.960
(Robert Muir-Wood) Now[br]we do not know exactly

0:20:26.960,0:20:29.600
where the next Cascadia[br]earthquake is going to occur,

0:20:29.600,0:20:30.440
but we do know that

0:20:30.440,0:20:33.800
the impact of that earthquake[br]in terms of the ground shaking,

0:20:33.800,0:20:36.360
the huge area impacted,

0:20:36.360,0:20:39.080
the extent of land level changes,

0:20:39.080,0:20:41.560
the size of the tsunami [br]which will be generated,

0:20:41.560,0:20:42.920
will be very comparable

0:20:42.920,0:20:48.120
to that which was seen[br]on December the 26th in 2004.

0:20:48.120,0:20:51.600
(narrator) Scientists believe[br]the next Cascadia earthquake

0:20:51.600,0:20:54.720
will be one of the largest on the planet,

0:20:54.720,0:20:57.080
up to magnitude 9.

0:20:59.760,0:21:03.400
The Kobe earthquake[br]which killed 6000 people

0:21:03.400,0:21:10.400
and devastated the Japanese[br]economy was a magnitude 6.8.

0:21:10.400,0:21:12.960
The terrible Mexico City earthquake

0:21:12.960,0:21:20.160
which killed over 10,000 people was 8.1.

0:21:20.160,0:21:27.120
But a magnitude 9 releases many[br]times more energy than those.

0:21:27.120,0:21:29.200
(Tim Walsh) The magnitude[br]scale is logarithmic,

0:21:29.200,0:21:32.600
that is each one is 10 times bigger[br]than the previous number.

0:21:32.600,0:21:34.760
But that's the amount of displacement.

0:21:34.760,0:21:37.640
When you do that [br]in terms of energy release,

0:21:37.640,0:21:41.080
each one is 30 to 40 times[br]bigger than the previous one.

0:21:41.080,0:21:46.640
So a magnitude 9 has 1000 times[br]more energy released

0:21:46.640,0:21:48.320
than does a magnitude 7,

0:21:48.320,0:21:50.760
30,000 more than a magnitude 6.

0:21:50.760,0:21:53.320
So to put that in perspective,

0:21:53.320,0:21:57.240
the Kobe earthquake that[br]was so damaging in Japan,

0:21:57.240,0:21:59.640
was about a magnitude 6.8.

0:21:59.640,0:22:03.200
So a Cascadia event that[br]would reach magnitude 9

0:22:03.200,0:22:05.400
is more than 1000 times[br]bigger than that one.

0:22:09.920,0:22:12.360
(narrator) Just as happened[br]in the Indian Ocean,

0:22:12.360,0:22:17.200
this huge earthquake will cause[br]a sudden uplift of the sea floor.

0:22:17.200,0:22:21.240
And that will create a tsunami.

0:22:21.240,0:22:22.680
The Boxing Day tsunami

0:22:22.680,0:22:27.360
devastated the densely populated[br]northwest coast of Sumatra,

0:22:27.360,0:22:32.240
and almost totally destroyed[br]the town of Banda Aceh.

0:22:32.240,0:22:35.600
The cities of Seattle, Portland,[br]and Vancouver

0:22:35.600,0:22:40.160
will at least be spared that fate.

0:22:40.160,0:22:42.000
(Robert Muir-Wood) One of the[br]fortunate things about Cascadia

0:22:42.000,0:22:46.520
in comparison with northern Sumatra[br]is that the big towns and cities

0:22:46.520,0:22:53.000
aren't located right out[br]on the open ocean coast.

0:22:53.000,0:22:57.360
The complex of waterways in Washington[br]State means that the big ports

0:22:57.360,0:23:02.120
are actually located someway inland.

0:23:02.120,0:23:04.360
(narrator) However,[br]thousands of people do live

0:23:04.360,0:23:07.040
on the Pacific Northwest coast.

0:23:07.040,0:23:11.760
And in summer, the beaches[br]are a major draw to tourists.

0:23:11.760,0:23:16.920
(Tim Walsh) A lot of the population[br]on the Washington coast is vacationers.

0:23:16.920,0:23:21.040
The population can grow from just a[br]few thousand permanent population

0:23:21.040,0:23:24.080
to tens of thousands of visitors.

0:23:24.080,0:23:28.240
And if we have a Cascadia[br]subduction zone earthquake and tsunami

0:23:28.240,0:23:31.920
the wave crest would arrive[br]at Ocean Shores and Long Beach

0:23:31.920,0:23:33.760
within about a half hour

0:23:33.760,0:23:36.320
and that's a very short period of time

0:23:36.320,0:23:39.880
to be able to move a lot of people off[br]those peninsulas to high ground.

0:23:41.840,0:23:45.480
(narrator) So even though there are[br]no major cities on the coast,

0:23:45.480,0:23:50.800
there will still be many thousands[br]of people at risk from the tsunami.

0:23:50.800,0:23:56.480
But far more people will be[br]affected by the earthquake itself.

0:23:58.000,0:24:02.080
All the major cities in Washington,[br]Oregon, and British Colombia

0:24:02.080,0:24:06.000
are going to experience[br]strong ground shaking.

0:24:06.000,0:24:12.400
And this megathrust earthquake will[br]be very different from a normal quake.

0:24:12.400,0:24:16.320
(Robert Muir-Wood) Magnitude 9[br]earthquakes have these special characteristics.

0:24:16.320,0:24:19.600
One of them is that it takes[br]several minutes

0:24:19.600,0:24:22.600
for the fault to break [br]from one end to the other.

0:24:22.600,0:24:25.960
The fault rupture spreads out[br]a few kilometers a second,

0:24:25.960,0:24:29.120
but it still may take two or three minutes[br]to get from one end to the other.

0:24:29.120,0:24:31.320
And that means the earthquake[br]shaking goes on

0:24:31.320,0:24:35.400
for a very long period of time.

0:24:35.400,0:24:40.720
(narrator) If the full 600 mile length[br]of the Cascadia subduction zone ruptures,

0:24:40.720,0:24:44.600
it will mean the earthquake will[br]continue for as long as five minutes,

0:24:44.600,0:24:48.640
just like the Indonesian earthquake did.

0:24:48.640,0:24:52.000
(Prof. McGuire) The duration[br]of the event is very unusual

0:24:52.000,0:24:55.200
and in that sense alone [br]it can cause more damage.

0:24:55.200,0:24:56.840
An earthquake that goes on for longer

0:24:56.840,0:25:00.400
causes more damage generally than one[br]that is over within 10 or 20 seconds.

0:25:02.920,0:25:06.880
(narrator) So what damage will[br]several minutes of shaking do

0:25:06.880,0:25:08.560
to cities like Seattle?

0:25:13.440,0:25:17.480
Even though the Boxing Day earthquake[br]and the next Cascadia earthquake

0:25:17.480,0:25:19.920
may be very similar,

0:25:19.920,0:25:23.160
they could have very different effects.

0:25:23.160,0:25:27.640
In Indonesia, most of the damage[br]was caused by the tsunami

0:25:27.640,0:25:29.840
not the earthquake itself.

0:25:31.800,0:25:34.360
(Robert Muir-Wood) Most people's[br]houses are built out of wood.

0:25:34.360,0:25:38.640
There's some more modern[br]concrete construction,

0:25:38.640,0:25:41.160
but typically only one or two story buildings,

0:25:41.160,0:25:43.760
so these buildings are not sensitive

0:25:43.760,0:25:46.560
to the very long period ground motions

0:25:46.560,0:25:49.680
we can expect from [br]a magnitude 9 earthquake.

0:25:51.560,0:25:55.320
(narrator) But the modern high-rise[br]structures of the Pacific Northwest

0:25:55.320,0:25:58.200
may react very differently.

0:25:58.200,0:26:05.800
♪ [piano music]

0:26:05.800,0:26:10.840
Tom Heaton is an earthquake[br]engineer from California.

0:26:10.840,0:26:14.880
He was brought in to advise on the[br]construction of a nuclear power station

0:26:14.880,0:26:17.560
near the Washington coast.

0:26:17.560,0:26:23.880
In the end, the project ran out of[br]money and was never completed.

0:26:23.880,0:26:27.120
But ever since, [br]Heaton has been concerned

0:26:27.120,0:26:31.560
by the question of what damage[br]a Cascadia earthquake could do,

0:26:31.560,0:26:34.680
particularly to skyscrapers.

0:26:35.920,0:26:40.080
(Tom Heaton) My fear is that in[br]a Cascadia event these buildings

0:26:40.080,0:26:42.240
may sway some large distance

0:26:42.240,0:26:45.600
as we get a very long[br]duration of shaking

0:26:45.600,0:26:49.600
that the swaying may grow in intensity

0:26:49.600,0:26:52.480
and the buildings may begin to be damaged.

0:26:54.600,0:26:58.800
(narrator) But not everyone agrees.

0:26:58.800,0:27:01.000
John Hooper is a buildings engineer

0:27:01.000,0:27:05.240
who has worked on many[br]of Seattle's tallest buildings.

0:27:05.240,0:27:08.440
He believes that the modern[br]skyscrapers, at least,

0:27:08.440,0:27:12.200
should be strong enough[br]to avoid serious damage.

0:27:12.200,0:27:13.720
(John Hooper) The majority[br]of the high-rises here,

0:27:13.720,0:27:14.600
they'll move.

0:27:14.600,0:27:15.840
And they'll move a lot.

0:27:15.840,0:27:19.760
But they're designed to withstand[br]that motion and that energy absorption

0:27:19.760,0:27:23.680
and they go through that[br]8 or 10 foot drift, back and forth

0:27:23.680,0:27:25.520
during the earthquake for several minutes,

0:27:25.520,0:27:27.040
scaring a lot of people probably,

0:27:27.040,0:27:30.560
but the damage should be related[br]mainly to the nonstructural components

0:27:30.560,0:27:33.440
and not to the major structural[br]elements themselves.

0:27:34.920,0:27:36.560
(narrator) The reality is,

0:27:36.560,0:27:39.160
no one knows for sure.

0:27:39.160,0:27:42.000
Because there has never been[br]a megathrust earthquake

0:27:42.000,0:27:45.480
near a modern high-rise city.

0:27:45.480,0:27:48.320
(Tom Heaton) These very large[br]earthquakes don't happen often

0:27:48.320,0:27:52.760
and for us to understand what it is[br]we need to do in the first place

0:27:52.760,0:27:55.760
so the building codes have[br]never really been tested

0:27:55.760,0:27:58.000
by an earthquake of this nature,

0:27:58.000,0:28:00.480
at least not for tall buildings.

0:28:00.480,0:28:03.480
The lessons haven't been learned yet.

0:28:03.480,0:28:06.080
So what concerns me is that

0:28:06.080,0:28:08.600
we may learn the lesson[br]in a very difficult way.

0:28:13.080,0:28:17.320
(narrator) But there is a type of building[br]that everyone agrees will be at risk.

0:28:21.080,0:28:27.960
The older brick buildings known as[br]unreinforced masonry, or URMs.

0:28:29.240,0:28:31.400
(John Hooper) These buildings we see[br]around here in [inaudible]Square

0:28:31.400,0:28:33.280
are like many cities on the west coast.

0:28:33.280,0:28:36.320
They are constructed of[br]unreinforced masonry,

0:28:36.320,0:28:38.720
brick stacked upon brick,[br]separated by mortar

0:28:38.720,0:28:40.800
and so if an earthquake shaking happens,

0:28:40.800,0:28:44.080
those brick end up sliding[br]past one another,

0:28:44.080,0:28:47.080
they lift apart.

0:28:47.080,0:28:50.920
(narrator) URM buildings are[br]very weak and very brittle.

0:28:50.920,0:28:55.200
So the long duration of shaking that[br]a megathrust earthquake will produce

0:28:55.200,0:28:58.600
could cause many to collapse.

0:28:58.600,0:29:02.880
(John Hooper) URM buildings have[br]been noticeably not very resistant

0:29:02.880,0:29:04.520
to earthquakes in general.

0:29:04.520,0:29:06.200
And if you don't do some renovations

0:29:06.200,0:29:07.720
and start connecting the pieces together,

0:29:07.720,0:29:09.160
they're very susceptible to damage,

0:29:09.160,0:29:12.560
especially during a long event[br]like the Cascadia.

0:29:12.560,0:29:15.560
And so even those that do have some[br]improvements made to them,

0:29:15.560,0:29:17.000
they still might be challenged.

0:29:17.000,0:29:18.760
But those that don't' have any,

0:29:18.760,0:29:21.560
their chances of surviving[br]is probably fairly limited.

0:29:24.160,0:29:27.280
(narrator) There are thousands of[br]these unreinforced masonry buildings

0:29:27.280,0:29:29.560
in the earthquake zone.

0:29:29.560,0:29:35.400
They are used as homes,[br]offices, and schools.

0:29:35.400,0:29:40.480
The collapse of such buildings is likely[br]to be a major cause of death and injury

0:29:40.480,0:29:43.480
when the next Cascadia earthquake occurs.

0:29:46.200,0:29:48.520
So the big question is,

0:29:48.520,0:29:50.360
"When will it happen?"

0:29:56.120,0:29:59.400
Predicting earthquakes is impossible.

0:29:59.400,0:30:00.520
No one could have known that

0:30:00.520,0:30:04.000
the Indonesian earthquake[br]was about to happen

0:30:04.000,0:30:08.840
and no one can say[br]when Cascadia will strike.

0:30:08.840,0:30:12.480
But it is possible to look back[br]at the geological record

0:30:12.480,0:30:18.640
and see how frequently earthquakes[br]occur on a particular fault.

0:30:18.640,0:30:20.200
Sure enough,

0:30:20.200,0:30:22.680
the Washington coast does hold traces

0:30:22.680,0:30:25.920
of several past megathrust earthquakes

0:30:25.920,0:30:29.240
from even before 1700.

0:30:29.240,0:30:32.560
(Brian Atwater) About 2,500 years[br]of earthquake history,

0:30:32.560,0:30:37.520
one, two, three, four events recorded.

0:30:37.520,0:30:39.560
Radio carbon ages show that

0:30:39.560,0:30:44.840
this event happened[br]about 600 years BC

0:30:44.840,0:30:51.000
and that this event happened[br]about AD 400.

0:30:51.000,0:30:57.000
So something about 1000 years[br]between this event and this event,

0:30:57.000,0:30:59.800
a very, very long time.

0:30:59.800,0:31:02.600
This event's from about AD 700.

0:31:02.600,0:31:07.680
There are only about three centuries[br]between this event and this event.

0:31:07.680,0:31:11.640
This is about the same amount of time[br]as between here and today.

0:31:11.640,0:31:14.440
So this is why it would not be[br]surprising if,

0:31:14.440,0:31:15.560
while we're standing here,

0:31:15.560,0:31:17.880
another one of these great[br]Cascadia earthquakes happened

0:31:17.880,0:31:19.360
and we have to run to high ground.

0:31:24.720,0:31:27.480
(narrator) And that is the problem.

0:31:27.480,0:31:32.320
The next megathrust earthquake[br]may not happen for centuries.

0:31:32.320,0:31:34.640
Or it could be imminent.

0:31:34.640,0:31:37.640
No one knows.

0:31:37.640,0:31:41.080
We don't know whether the entire[br]Cascadia fault will rupture

0:31:41.080,0:31:43.760
like it did in 1700.

0:31:43.760,0:31:47.840
We don't know how badly affected[br]the modern cities will be.

0:31:51.880,0:31:55.880
But Yumei Wang, director[br]of Geo Hazards for Oregon,

0:31:55.880,0:31:58.720
believes we must still take action.

0:31:58.720,0:32:02.320
(Yumei Wang) We know that a[br]Cascadia earthquake is inevitable.

0:32:02.320,0:32:04.280
We can't prevent earthquakes.

0:32:04.280,0:32:08.720
But one thing that we can do[br]is prevent a lot of the damage.

0:32:08.720,0:32:11.600
We can save lives if we prepare now.

0:32:15.760,0:32:19.840
(narrator) That preparation must be[br]based on our current understanding

0:32:19.840,0:32:26.040
of what the next Cascadia[br]earthquake will be like.

0:32:26.040,0:32:28.440
What follows is a reconstruction

0:32:28.440,0:32:33.320
based on the knowledge of leading [br]experts of what may happen;

0:32:33.320,0:32:39.560
what it would look and feel like to[br]experience a megathrust earthquake.

0:32:50.120,0:32:52.680
(Tim Walsh) We don't know what[br]actually sets the earthquake off.

0:32:52.680,0:32:57.880
But typically it would probably start[br]at some rough spot on the fault.

0:33:02.320,0:33:07.440
(narrator) The rupture is most[br]likely to start at one end of the fault.

0:33:07.440,0:33:13.320
It would then spread along the fault[br]at over 7000 miles per hour.

0:33:13.320,0:33:17.720
As it tears, the North American plate[br]which has been pushed inward

0:33:17.720,0:33:21.760
would spring back, releasing the strain.

0:33:21.760,0:33:25.120
(Robert Muir-Wood) There may be[br]a region 4 or 500 kilometers long

0:33:25.120,0:33:32.400
where the seafloor has suddenly[br]risen up by 2 or 3 meters.

0:33:32.400,0:33:37.560
It happens so fast that it lifts up[br]the whole body of the water on top of it.

0:33:37.560,0:33:42.520
And as a result, suddenly the sea[br]surface finds itself 2 or 3 meters higher

0:33:42.520,0:33:43.520
than it was before,

0:33:43.520,0:33:46.680
over a large area, [br]and that sets off a wave.

0:33:50.240,0:33:52.800
(narrator) This is the tsunami

0:33:52.800,0:33:56.240
which would radiate out in all directions.

0:33:56.240,0:33:59.880
Part of it would head out into the Pacific.

0:33:59.880,0:34:04.000
And part would head directly[br]for the coast of North America.

0:34:05.040,0:34:08.400
(Tim Walsh) It travels at the same[br]speed roughly as an airliner

0:34:08.400,0:34:11.440
out in the open ocean,[br]perhaps 600 miles an hour.

0:34:14.040,0:34:15.480
(narrator) Even at that speed,

0:34:15.480,0:34:19.800
it would take many hours to[br]reach the other Pacific nations.

0:34:19.800,0:34:23.080
It would take 5 hours to reach Hawaii.

0:34:23.080,0:34:27.000
And more than 10 hours to reach Japan.

0:34:27.000,0:34:30.639
Thanks to the sophisticated Pacific[br]tsunami network,

0:34:30.639,0:34:33.000
those countries would get a warning.

0:34:37.679,0:34:41.239
(Prof. McGuire) The quake will be[br]detected by a network of seismographs.

0:34:41.239,0:34:43.320
The tsunami, if they form,

0:34:43.320,0:34:48.000
will be spotted and identified[br]and tracked by seabed sensors

0:34:48.000,0:34:50.239
which will send,[br]via buoys on the surface,

0:34:50.239,0:34:52.400
a radio message, via satellite,

0:34:52.400,0:34:55.280
to the emergency authorities in[br]the countries around the Pacific Rim

0:34:55.280,0:34:56.520
who might be affected.

0:34:56.520,0:35:01.840
It's then their job to tell their populations[br]to evacuate the coastal region.

0:35:01.840,0:35:04.160
(narrator) This warning system[br]should make the distant effect

0:35:04.160,0:35:05.560
of a Cascadia earthquake

0:35:05.560,0:35:08.960
very different from[br]the events of Boxing Day.

0:35:08.960,0:35:10.560
(Prof. McGuire) I think that[br]the loss of life remote

0:35:10.560,0:35:14.680
from the actual location of the Cascadia[br]earthquake will be small

0:35:14.680,0:35:16.640
when the next big event occurs.

0:35:16.640,0:35:17.720
And this is because,

0:35:17.720,0:35:20.560
although the waves travel[br]at the speed of a jumbo jet,

0:35:20.560,0:35:23.960
maybe 8 or 900 km an hour[br]across the Pacific,

0:35:23.960,0:35:25.720
it's s huge ocean basin

0:35:25.720,0:35:29.360
and it will take many hours for the wave[br]to reach places like Hawaii, Japan,

0:35:29.360,0:35:30.920
which will probably be badly hit,

0:35:30.920,0:35:36.080
but they will have plenty of time[br]to evacuate people to safe ground.

0:35:36.080,0:35:40.800
(narrator) But the situation in the[br]Pacific Northwest would be very different.

0:35:40.800,0:35:45.320
The tsunami would arrive there[br]in half an hour.

0:35:45.320,0:35:51.160
And they'd have the earthquake[br]to deal with first.

0:35:51.160,0:35:53.640
The seismic waves[br]which carry the shaking

0:35:53.640,0:35:57.680
would be travelling through the earth[br]at over 10,000 miles per hour,

0:35:57.680,0:36:02.120
much faster than the tsunami.

0:36:02.120,0:36:07.320
In just a few seconds [br]the earthquake would reach the land.

0:36:11.480,0:36:15.440
The earthquake would be at its[br]most violent here on the coast.

0:36:15.440,0:36:17.400
(John Hooper) There right[br]at ground zero, the shaking.

0:36:17.400,0:36:20.160
So the shaking they feel will be[br]the largest of anybody

0:36:20.160,0:36:22.320
because they're nearest[br]to the fault rupture.

0:36:27.080,0:36:30.920
(narrator) But the shaking wouldn't[br]have reached the inland cities yet.

0:36:30.920,0:36:36.200
People here wouldn't even know[br]that an earthquake had started.

0:36:36.200,0:36:40.680
However news would have reached[br]the emergency services.

0:36:47.000,0:36:51.360
This is the Washington State[br]Emergency Operations Center.

0:36:51.360,0:36:54.360
It would be one of the first places[br]to receive an alert

0:36:54.360,0:36:57.720
from the tsunami warning center.

0:36:57.720,0:37:00.360
(male # 1) Magnitude 9.

0:37:00.360,0:37:05.800
(male # 2) We're activating our EOC[br]to a phase 3 for a tsunami.

0:37:05.800,0:37:08.960
(narrator) Horizon filmed them[br]rehearsing for a major earthquake.

0:37:11.920,0:37:15.880
The two on duty officers would[br]immediately activate the center

0:37:15.880,0:37:17.800
and start calling in staff.

0:37:19.600,0:37:22.760
(male #2) And what could be[br]your possible ETA to the EOC?

0:37:22.760,0:37:27.720
(narrator) Their job would be to[br]coordinate the emergency response.

0:37:27.720,0:37:30.800
But there would be no time[br]to issue a public warning

0:37:30.800,0:37:33.400
before the earthquake hits the big cities.

0:37:38.840,0:37:41.960
Up to two minutes after[br]the start of the earthquake

0:37:41.960,0:37:47.280
the seismic waves would[br]reach the city of Seattle.

0:37:47.280,0:37:48.960
Because of the distance,

0:37:48.960,0:37:52.600
the different types of seismic wave [br]would have separated out

0:37:52.600,0:37:57.360
with the faster compression waves[br]reaching the city first.

0:37:57.360,0:38:02.160
(John Hooper) The first thing you[br]sense is a vertical acceleration.

0:38:02.160,0:38:03.520
You get pushed up a little bit

0:38:03.520,0:38:06.680
and you think it's maybe [br]it's the jolt of a train going by

0:38:06.680,0:38:08.080
or something of that type.

0:38:10.400,0:38:11.480
(Tom Heaton) But then later,

0:38:11.480,0:38:15.000
maybe 20 seconds even later[br]you might feel,

0:38:15.000,0:38:19.280
start to feel the shear waves coming in[br]which are shearing motions in the earth,

0:38:19.280,0:38:21.520
the kind of motion that[br]does most of the damage.

0:38:26.640,0:38:29.880
(narrator) These shear waves would[br]move the earth from side to side

0:38:29.880,0:38:32.880
by as much as a meter.

0:38:32.880,0:38:35.320
There would also be surface waves,

0:38:35.320,0:38:38.560
like ocean waves, rippling[br]through the solid earth.

0:38:39.360,0:38:42.080
(Yumei Wang) If you are in a parking lot,

0:38:42.080,0:38:47.040
it's likely that you see waves[br]rolling across the parking lot

0:38:47.040,0:38:49.360
like if you took a carpet and shook it.

0:38:52.640,0:38:55.920
(narrator) As the shaking[br]becomes more and more intense,

0:38:55.920,0:39:00.520
people would realize that[br]this was no ordinary earthquake.

0:39:00.520,0:39:03.120
(John Hooper) That shaking[br]will continue to build.

0:39:03.120,0:39:04.760
You'll feel the first sway

0:39:04.760,0:39:06.880
and it'll start to build and build and build

0:39:06.880,0:39:08.560
and you'll wonder[br]when it's going to stop.

0:39:10.800,0:39:14.760
(narrator) Indoors, objects and[br]furniture will be hurled about the room.

0:39:14.760,0:39:17.480
Parts of the building may start to fall.

0:39:17.480,0:39:19.840
(Yumei Wang) Right when you feel[br]the earthquake shaking,

0:39:19.840,0:39:25.240
what we train people to do[br]is to duck, cover, and hold.

0:39:25.240,0:39:27.680
[children screaming]

0:39:27.680,0:39:31.600
(narrator) Schools and offices now[br]practice this life saving maneuver.

0:39:31.600,0:39:35.040
Going under a strong desk[br]and holding onto it.

0:39:37.880,0:39:40.680
(Yumei Wang) Anything that might[br]fall won't fall on you directly.

0:39:40.680,0:39:42.200
It will fall on the table

0:39:42.200,0:39:46.280
and the whole time you protect[br]your [missing audio].

0:39:46.280,0:39:47.560
(narrator) For people outside,

0:39:47.560,0:39:51.880
the major hazard will be falling[br]debris and shattering glass.

0:39:51.880,0:39:53.840
(Yumei Wang) If you're outside somewhere,

0:39:53.840,0:39:57.040
the best thing to do is to move[br]quickly into open space

0:39:57.040,0:40:01.360
such as away from a building[br]where you might have falling objects.

0:40:04.240,0:40:07.280
(narrator) Buildings would now[br]be exposed to huge forces

0:40:07.280,0:40:11.360
as they're shunted back and forth.

0:40:11.360,0:40:13.640
They unreinforced masonry buildings

0:40:13.640,0:40:17.440
would be the first to suffer damage.

0:40:17.440,0:40:21.200
(Yumei Wang) The weakest points[br]start to fail, in most cases,

0:40:21.200,0:40:23.160
because they're older structures.

0:40:23.160,0:40:24.240
It's the mortar.

0:40:24.240,0:40:25.840
(John Hooper) The elements[br]that support the building vertically,

0:40:25.840,0:40:27.000
if they start to come down,

0:40:27.000,0:40:29.680
the floors themselves[br]potentially can come down.

0:40:32.360,0:40:35.760
(narrator) Collapsing URMs[br]could cause many fatalities

0:40:35.760,0:40:41.200
throughout the region.

0:40:41.200,0:40:45.960
The shaking in Seattle would now[br]have been going on for two minutes.

0:40:45.960,0:40:49.520
But we'd only be hallway through.

0:40:49.520,0:40:51.120
(Yumei Wang) For a typical earthquake,

0:40:51.120,0:40:55.640
if a building gets damaged[br]in the first 20, 30 seconds,

0:40:55.640,0:40:58.720
it very likely can remain standing.

0:40:58.720,0:41:03.760
But if that damaged building is[br]shaken for another three minutes

0:41:03.760,0:41:07.960
then that damage can[br]propagate into collapse.

0:41:10.840,0:41:13.760
(narrator) Meanwhile, the large[br]movements of the ground

0:41:13.760,0:41:17.600
would be making skyscrapers[br]bend further and further.

0:41:17.600,0:41:22.320
(Tom Heaton) you may see the buildings[br]begin to sway more and more violently

0:41:22.320,0:41:26.520
to the point where they start[br]to perhaps lose windows.

0:41:26.520,0:41:32.240
They may, in addition, start to[br]have some fracturing of welds

0:41:32.240,0:41:35.360
in steel frame buildings.

0:41:35.360,0:41:39.360
What happens after that[br]is anybody's guess.

0:41:42.600,0:41:46.120
(narrator) The worst case scenario[br]would be the total collapse

0:41:46.120,0:41:47.880
of a high-rise building.

0:41:52.760,0:41:55.160
Meanwhile, buildings on higher ground

0:41:55.160,0:41:58.400
would be suffering their own problems.

0:41:58.400,0:42:02.360
(Tim Walsh) Earthquakes this large[br]can generate landslides at distances

0:42:02.360,0:42:07.480
of up to hundreds of miles away.

0:42:07.480,0:42:10.960
(John Hooper) The classic worst[br]case scenario where you're on a hill,

0:42:10.960,0:42:12.680
the land slides,[br]your house goes with it

0:42:12.680,0:42:14.760
and the house will obviously be destroyed.

0:42:28.880,0:42:31.240
(narrator) Five minutes after[br]the start of the earthquake

0:42:31.240,0:42:34.600
the rupture would have reached[br]the northern end of the fault.

0:42:34.600,0:42:38.720
Vancouver would still be[br]experiencing powerful shaking,

0:42:38.720,0:42:42.560
but in Seattle, the earthquake[br]would finally be subsiding.

0:42:48.720,0:42:51.920
For people in buildings that[br]have suffered structural damage,

0:42:51.920,0:42:55.120
now it would be time to evacuate.

0:42:55.120,0:42:59.160
What would have felt like the longest[br]few minutes of people's lives

0:42:59.160,0:43:01.320
will finally be over.

0:43:03.680,0:43:05.400
But on the coast,

0:43:05.400,0:43:08.480
the ordeal would have only just begun.

0:43:13.080,0:43:16.240
The tsunami unleashed[br]by the earthquake,

0:43:16.240,0:43:19.880
would be minutes away.

0:43:19.880,0:43:21.840
For the Pacific Northwest

0:43:21.840,0:43:26.800
the tsunami warning system[br]that should save lives across the world,

0:43:26.800,0:43:30.560
would be virtually useless.

0:43:30.560,0:43:33.480
(Tim Walsh) There won't be time[br]for the tsunami warning center

0:43:33.480,0:43:35.120
to detect that earthquake,

0:43:35.120,0:43:37.880
make a determination[br]whether or not it was tsunamigenic ,

0:43:37.880,0:43:41.440
then send a warning down to[br]emergency managers in Washington

0:43:41.440,0:43:43.400
who will then send it to the people.

0:43:43.400,0:43:47.680
That would waste valuable time.

0:43:47.680,0:43:50.200
People need to know that[br]when they feel strong shaking

0:43:50.200,0:43:51.440
if they're on the coast,

0:43:51.440,0:43:54.120
they need to go to high ground and/or inland.

0:43:54.120,0:43:58.200
♪ [music playing]

0:43:58.200,0:44:00.480
(narrator) The tsunami will[br]have started out as a wave

0:44:00.480,0:44:02.640
of only a meter or two high

0:44:02.640,0:44:05.600
travelling at huge speed.

0:44:05.600,0:44:07.480
But as it nears the coast,

0:44:07.480,0:44:10.320
it starts to rise up.

0:44:10.320,0:44:11.640
(Tim Walsh) Those waves can grow.

0:44:11.640,0:44:15.480
They can amplify as more and more[br]water piles up in shallow water

0:44:15.480,0:44:18.480
and all of that energy [br]then causes the wave to

0:44:18.480,0:44:20.800
slow down and grow in amplitude

0:44:20.800,0:44:25.240
and create waves that have been[br]known to be hundreds of feet high.

0:44:25.240,0:44:29.000
(Robert Muir-Wood) That first wave[br]is often simply a step in the water level

0:44:29.000,0:44:33.040
and the water level then[br]stays up high for 5 or 10 minutes

0:44:33.040,0:44:35.200
before it eventually drains away again.

0:44:38.200,0:44:40.640
(narrator) Just as happened in Indonesia,

0:44:40.640,0:44:42.840
within half an hour of the earthquake,

0:44:42.840,0:44:45.640
the tsunami would rush onto the land,

0:44:45.640,0:44:51.600
more like an ever growing tide [br]than a normal wave.

0:44:51.600,0:44:55.920
Anyone who doesn't manage to get[br]inland and to high ground in time

0:44:55.920,0:44:57.640
would be unlikely to survive.

0:45:08.040,0:45:13.640
The tsunami will devastate[br]hundreds of miles of coast.

0:45:13.640,0:45:20.280
In total, more than 50,000 square[br]miles will be affected by the earthquake.

0:45:20.280,0:45:23.040
(Yumei Wang) Unfortunately, [br]I don't think people understand

0:45:23.040,0:45:27.000
that a Cascadia earthquake[br]is going to be so very different

0:45:27.000,0:45:30.440
than the other types of earthquakes[br]that we've all experienced,

0:45:30.440,0:45:33.760
or many of us have experienced.

0:45:33.760,0:45:39.000
One of the main differences is that[br]it's going to affect such a large region.

0:45:39.000,0:45:43.280
(John Hooper) It's not just going[br]to be city of Seattle or city of Portland.

0:45:43.280,0:45:47.960
It could be an 800 mile stretch of[br]Washington, Oregon, and California

0:45:47.960,0:45:49.040
that gets affected.

0:45:54.760,0:45:56.560
(narrator) Until recently,

0:45:56.560,0:45:58.240
many people would[br]have found it difficult

0:45:58.240,0:46:02.360
to imagine that scale of devastation.

0:46:02.360,0:46:06.040
But the Boxing Day disaster[br]changed all that.

0:46:09.080,0:46:12.000
(Prof. McGuire) The Indian Ocean[br]earthquake and tsunami

0:46:12.000,0:46:15.240
will remind these people that are[br]living in the Pacific Northwest that

0:46:15.240,0:46:17.920
this is something they[br]will have to face in the future

0:46:17.920,0:46:20.240
and the window of opportunity[br]that now exists

0:46:20.240,0:46:22.160
should be used to make sure that

0:46:22.160,0:46:24.520
the people that live in that[br]part of the word are educated

0:46:24.520,0:46:28.000
in terms of how to respond[br]when the earthquake happens.

0:46:28.000,0:46:30.000
(teacher) Quickly.[br]Quickly, all of you.

0:46:30.000,0:46:32.760
(narrator) The simple knowledge[br]that after an earthquake

0:46:32.760,0:46:34.840
people should move away from the ocean

0:46:34.840,0:46:36.520
and to high ground

0:46:36.520,0:46:39.200
can save lives.

0:46:39.200,0:46:42.120
The scientists who[br]discovered this threat

0:46:42.120,0:46:44.240
are now playing their part [br]in spreading the word

0:46:44.240,0:46:45.520
to as many people as possible.

0:46:45.520,0:46:50.040
(Brian Atwater) That line goes[br]all the way up to a salt marsh.

0:46:50.040,0:46:52.240
(narrator) Before the next earthquake.

0:46:54.920,0:46:57.800
(Yumei Wang) We knew that this[br]Cascadia earthquake is imminent .

0:46:57.800,0:46:59.800
It's imminent in geologic time.

0:46:59.800,0:47:03.360
So basically we're in a race against time

0:47:03.360,0:47:05.600
and the more we can get done now,

0:47:05.600,0:47:07.080
the more lives we'll save.

0:47:08.960,0:47:12.000
(David Yumaguchi) If we have[br]10 years, is that enough?

0:47:12.000,0:47:12.840
Probably not.

0:47:12.840,0:47:15.400
If we have 50 years, maybe, you know.

0:47:15.400,0:47:18.160
If we have a century,

0:47:18.160,0:47:19.640
you know, maybe we'll really be ready.

0:47:19.640,0:47:22.440
But do we have a century?

0:47:22.440,0:47:23.840
We don't know.

0:47:23.840,0:47:27.280
♪ [music playing]

0:47:27.280,0:47:29.080
(narrator) The Indonesian earthquake

0:47:29.080,0:47:31.840
has given the people of the Pacific Northwest

0:47:31.840,0:47:36.840
a glimpse of what[br]they will one day face.

0:47:36.840,0:47:40.680
Now they must heed it's warning.

0:47:40.680,0:47:41.400
♪ [theme music plays]