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Just after lunchtime on March 11th,

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the most powerful earthquake ever
measured in Japan shook the country.

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It was big enough to shift
the Earth on its axis.

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It sent a tsunami ten metres high
racing towards the mainland.

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The Tohoku earthquake had
unleashed on to Japan one of the
great forces on the planet.

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People had just minutes
to save their lives.

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The tsunami then triggered
a near-meltdown in one of the
country's nuclear power stations.

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The disaster has claimed over
10,000 lives. Almost twice as many
are still missing.

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When something as shocking as this
happens,

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it's hard to see past
the terrible loss of life
and devastation.

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Certainly, it makes you appreciate
the power that our planet holds

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over our lives, our cities,
over our civilisation.

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And in that sense,
it raises fundamental questions

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about my science -
the science of earthquakes.

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In this film, I'll be looking
at the causes of this earthquake
deep within the planet.

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I'll be examining its consequences
and finding out whether
this earthquake

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could trigger another big one.

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Two weeks after the earthquake,
people are still struggling

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to come to terms
with the scale of this disaster.

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Aftershocks are a daily occurrence.

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So far, there have been over 700.

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Normally in Japan, earthquakes don't
cause this kind of destruction.

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But the events of the last
fortnight have been far from normal.

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As emergency crews help
those left among the ruins,
scientists worldwide

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are now starting to work out what
made this earthquake so powerful
and so deadly.

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I've come to the Royal Society
in London to piece together
the anatomy of this disaster.

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When I heard the news and watched
those first images, it was clear
that this was something different.

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Something really unusual.

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Big earthquakes like this are
few and far between,
and as an earthquake geologist,

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you're immediately intrigued
as to just what happened.

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Crucial evidence is already
starting to emerge
in the seismic record.

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These are seismic traces,
blow-by-blow accounts of
earthquake jolts deep underground.

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This happens to be a
quiet morning in Japan.

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3:00am, hardly anything
happening. There's a
little rattle towards the end.

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3.10, 3.20, nothing. 3:50.
4:00am - another little rattle.

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But if this is a quiet day, then
look at it when the big shock comes.

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Here it is. It's been quiet
before 12:00pm, and then through
the afternoon,

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and then here, 14.46,
the big one strikes.

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The needle just goes off the scale
and then what happens is... Well,

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all hell breaks loose - just a storm
of aftershocks that sweeps its way
through juddering and jolting Japan.

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But the thing is that it's wrong
to think of this event
just somehow in isolation.

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What we can see if we take a longer
view of this is that earthquakes are
happening all the time in Japan.

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Here is the big one,
the 11th of March, big quake,
and here are all the aftershocks,

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but two days before, another
pretty big earthquake.

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And that's the point - Japan is
just incredibly seismically active.

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This seismic activity
is all down to a fragile jigsaw
of tectonic plates -

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giant slabs of rock which move
across the planet's surface.

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Heat generated by Earth's core
keeps these plates
constantly in motion.

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Where they grind together,
huge forces build up.

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When the pressure gets too much,
the edges of the plates
suddenly slip...

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causing an earthquake.

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This map shows where earthquakes
happen in the world, something
like 100,000 every year.

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But 30% of those are up here in
Japan. You can see them, black
dots all the way around here,

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past Alaska here, and down
to California where the famous San
Andreas fault line rips through.

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Then over here,
here's New Zealand.

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The line of earthquakes goes right
through it. Christchurch had
an earthquake last month.

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That was small compared to Japan,
and the reason for that
you can see on this close-up.

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Japan sits at the meeting place
of at least four plates.

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There's one here, one here,
one here and one right underneath.

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And these numbers here, 90 under
northern Japan, is 90mm per year

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that the Pacific is moving towards
Japan. That's that much in a year.

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So the reason why Japan
is kind of earthquake country

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is because you've got all these
plates meeting and all the stress
gets concentrated under there.

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To really understand how events
unfold,

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you have to understand the time line
of an earthquake.

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This is the live TV feed
from the Japanese parliament.

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At 2:47pm, this appears.

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This is an automatic alert.
It warns TV viewers
that an earthquake has occurred.

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Unaware of this warning,
the delegates continue the debate

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as the announcer
reels off a list of areas
expected to be hardest hit.

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ANNOUNCER READS LIST OF AREAS

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What you're seeing is the gap
between the earthquake happening,

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and its shockwaves arriving
in Tokyo.

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But it's only a matter of seconds
before those shockwaves strike.

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Despite the obvious confusion
above ground,

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below, a very particular sequence
of events is beginning to unfold.

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The earthquake starts with the
sudden release of this immense
pent-up energy

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in these massive
tectonic plates.

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And within a few seconds,
huge seismic shockwaves race
outward from the epicentre.

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And the thing about shockwaves
generated by earthquakes is that
there are different kinds, but

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for the people of Japan on
11th March, there were two types
that were important.

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One is P waves - primary
waves - which kind of
push and pull the rocks.

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And the other is S waves -
secondary waves - which
shear it from side to side.

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P waves travel much faster than
S waves, something like 10 times
the speed of sound,

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but S waves, although they
are 60% slower, are the ones
that do all the damage.

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The difference in the arrival times
turns out to be absolutely crucial
because sensors can detect P waves

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and can send out warnings to
mobile phones and TV stations.

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Although the gap between
the arrival of the two types
of waves is just a few seconds,

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that's precious enough time to get
clear of buildings and to take cover
before the dangerous S waves strike.

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Of course, when the first tremor
of an earthquake hits, nobody
knows what's coming next.

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And at first, it seems like
many of the other ground tremors
so common in Japan.

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But soon, the severity of
this quake becomes clear.

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PEOPLE START SHOUTING

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Let me set the scene. This is Tokyo,
Friday afternoon on 11th March.

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The P waves have just come through
and the deadly S waves
are starting to arrive.

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And you can tell they're arriving
because as we start to watch, these
sky scrapers are starting to sway.

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It's hard to see it on this
view, but if you zoom in,
you can really see it.

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That sky scraper is just
rocking back and forth.

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And what must it have been
like to be 20, 30 storeys up
there as that sways back and forth?

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Absolutely terrifying.

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LOUD CREAKING

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People immediately turn to the
earthquake drills which have been
rehearsed so often in Japan.

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But as the intensity of this
earthquake increases,

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it's clear that this is on a scale
that nobody has anticipated
or rehearsed for.

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The shockwaves are starting
to tear at the fabric of the city.

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Earthquake right now.

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This is actually moving.

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See the cracks moving?

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That crack was not there.
DOG BARKS WILDLY

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This footage just absolutely
takes your breath away.

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What we're seeing is a path of
concrete or asphalt just being
ripped apart by the shaking.

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See how it's moving up and down.

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The reason for that is because
although the shockwaves come from
tens of kilometres down

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and travel upwards,

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it's in the uppermost few metres

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that they're at their most
destructive,

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because as the vibrations move from
the solid rock into the looser
sand and muds of the soil,

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the vibrations amplify so they get
more destructive.

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Look at that. You can see the whole
thing moving back and forth.

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The whole ground
is behaving like jelly.

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It's shaking for a long time.

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From start to finish, the earthquake
rupture is five minutes.

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Imagine standing for five minutes in
the park and it's like the open sea
- you're getting tossed around.

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The reason for the land
moving back and forth

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is because under there, there's
water trying to get out.

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It's been trapped in the soil and
there earthquake has released it.
It's bursting open. There it goes.

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This is called liquefaction - the
ground is literally turning
into a liquid.

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After a few minutes,
the shaking reaches its peak.

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So great are these forces that
they are felt in towns and cities
across much of Japan.

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The spread and extent of
this shaking has already been
mapped by seismologists.

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The red parts show the areas
which shook hardest.

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Great swathes of the Japanese
mainland are severely affected.

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You probably heard on the news that
this event of March 11th measured
nine on the magnitude scale

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and that scientists have labelled
this a mega-thrust earthquake.

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But what does all that mean?

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It's been calculated that the
energy released in this event

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was 600 million times greater
than that released in the nuclear
bomb that destroyed Hiroshima.

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But it's just so hard to
get your head around.

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The thing is as a geologist, you're
always looking at the big picture.

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And for an earthquake
like this, a giant quake.

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it doesn't get much bigger.

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Which is why the global effects
of this are truly staggering.

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Huge forces were released
by this earthquake.

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They shifted the Earth's axis
by up to 25cm.

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They changed the shape of a planet,

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which affects the speed at which
it rotates in space.

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The result?
The length of each day is now
a tiny bit shorter for all of us.

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It's hard to imagine how an
earthquake can reshape a planet,

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but consider this -

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Japan's East coast has lurched
four metres out towards the Pacific,

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and sunk by over a metre.

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But what made this earthquake
so big? And what triggered it?

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To find out, I visited the
University of Ulster, in Belfast.

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I've come here to meet one
of the top earthquake scientists
in the world

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and someone that I think
has got a real handle on what's
happened with the Japanese quake.

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Much of the data's still coming in,

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but already the picture
is becoming clearer.

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Professor John McCloskey is a
pioneer of earthquake research.

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He's spent years studying seismic
activity across the Pacific region

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where the earthquake occurred,

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and, crucially,
he's studying how stress builds up
in the Earth's plates

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and how that can set off
earthquakes.

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Well, to understand why an
earthquake ends up being
a big earthquake,

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we have to think really
about hundreds of years of very
slow, steady accumulation of stress.

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The very interesting thing is that
this now is a process

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where we have
a very highly stressed fault,

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with patches of very high
stress, and on to that

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we just put the smallest amount
of stress loading,

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and sometimes that can have
an amazingly large effect.

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Just two days before the
earthquake struck, another quake,
measuring 7.2, occurred nearby.

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Professor McCloskey believes

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that the stress transferred by
this smaller, earlier earthquake

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was enough to trigger the big one.

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So this is the situation,

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the 7.2 earthquake
started here and it shed
stress in the surrounding region.

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And the outside of the bull's-eye
is an area of increased stress.

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This area of additional stress
covers the location of the
big earthquake on March 11th.

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And what's remarkable
is how minimal the force of this
additional stress actually was.

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The amazing thing is that amount of
stress that's represented

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by these red colours,
is actually the amount
of stress in a gentle handshake.

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The force of an actual
handshake was all it took

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to trigger the earthquake which
made headlines around the world.

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So a big earthquake,
a magnitude nine,

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needs a handshake of stress
to start it off. That's phenomenal.

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A handshake is all that it takes.

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It's an extreme. It is the
straw that breaks the camel's back.

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Notice the straw,
it doesn't supply the force,

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it just supplies that extra
small load which is all it takes

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to trigger, in this case,
the release of such enormous
amounts of energy.

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And that energy
had to go somewhere.

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The violent earthquake now shaking
Japan had already unleashed
another force,

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one far more deadly.

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About three minutes after
the earthquake,

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Japan's Meteorological Agency
broke into TV broadcasts
with another warning.

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Analysis of the earthquake data had
predicted it would cause a tsunami.

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They were right.

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A giant wave was racing
across the ocean towards Japan.

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But people seemed to have
little sense of what was in store.

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After all, many buildings appeared
to have survived the earthquake.

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And tsunami warnings
are common here.

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But in reality,
people in some parts of the coast,

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now had just 20 minutes to escape
before the wave struck land.

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Tsunamis are fairly rare events
that are not entirely understood.

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But that may change

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because there's more
footage of this tsunami
than any other in history.

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For scientists, that footage from
news helicopters and mobile phones

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forms an extraordinary body
of information.

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And the hope is that by studying
these incredible images in detail,

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we'll understand where
the tsunami's great destructive
power comes from

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and also how to survive them.

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The ferocious power of
the tsunami began deep under
the sea inside the planet.

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The huge energy released by the
earthquake ruptured a 300 kilometre
stretch of the Earth's crust.

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It forced the seabed
up perhaps ten metres,

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driving a giant column of water
up above the surface of the ocean.

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The tower of water collapsed,

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sending a tsunami racing at
200 kilometres a hour

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00:21:25,440 --> 00:21:27,480
east across the Pacific ocean,

218
00:21:27,480 --> 00:21:30,920
and west towards Japan.

219
00:21:38,840 --> 00:21:44,760
The tsunami consisted of up
to ten individual waves,
each about a kilometre apart.

220
00:21:47,880 --> 00:21:52,520
This remarkable footage was
filmed on the Matsushima,

221
00:21:52,520 --> 00:21:57,720
a coastguard vessel 5 kilometres
out to sea off Japan's
north-eastern coast.

222
00:21:57,720 --> 00:22:02,080
It records the progress of
the tsunami through the ocean.

223
00:22:02,080 --> 00:22:08,040
On the bridge, the crew capture
the moment they crest the wave.

224
00:22:08,040 --> 00:22:12,840
CREW GASP

225
00:22:16,640 --> 00:22:20,960
As it neared the coast, the
tsunami became much more dangerous.

226
00:22:22,400 --> 00:22:24,080
In the shallow water,

227
00:22:24,080 --> 00:22:28,400
the individual waves began to
catch up with each other,
becoming higher.

228
00:22:31,120 --> 00:22:34,920
The tsunami had become
a giant wall of water.

229
00:22:46,160 --> 00:22:51,720
24 minutes after the earthquake,
the tsunami hit Japan's
northeast coast.

230
00:22:52,880 --> 00:22:56,280
In places, it was 15 metres high.

231
00:22:56,280 --> 00:22:59,520
That's as tall as
a three-storey building.

232
00:23:04,800 --> 00:23:07,040
PANICKED VOICES

233
00:23:07,040 --> 00:23:09,840
GASPING

234
00:23:26,880 --> 00:23:30,720
Our vulnerability in the face
of the Earth's natural forces,

235
00:23:30,720 --> 00:23:33,640
was captured as never before.

236
00:23:35,240 --> 00:23:41,040
These satellite images show how the
landscape was utterly transformed.

237
00:23:45,960 --> 00:23:49,920
In Japan, many of the communities
are forced to live on
the coastal plain

238
00:23:49,920 --> 00:23:54,960
just because the interior
is so mountainous and they know
the coastline is prone to tsunamis,

239
00:23:54,960 --> 00:23:59,800
but what this terrifying footage
shows is just how utterly uneven

240
00:23:59,800 --> 00:24:03,120
the balance is between people
and nature in this coastal zone.

241
00:24:03,120 --> 00:24:07,480
This is the fishing port of
Miyako, home to 60,000 people.

242
00:24:07,480 --> 00:24:10,960
Although I've seen this footage
loads of times on the news,

243
00:24:10,960 --> 00:24:15,640
what I hadn't realised is this
here is a ten-metre coastal wall,

244
00:24:15,640 --> 00:24:18,600
a sea wall designed to
protect against tsunamis.

245
00:24:18,600 --> 00:24:20,360
And you can see what's happened.

246
00:24:20,360 --> 00:24:23,320
The water's got so high
it's completely swamped it.

247
00:24:23,320 --> 00:24:25,680
Overwhelmed it. Look at that.

248
00:24:25,680 --> 00:24:29,160
40 per cent of the Japanese
coastline has a sea wall
like this.

249
00:24:29,160 --> 00:24:32,680
And the point is that
in times like this,

250
00:24:32,680 --> 00:24:35,840
when it's huge waves,
rather than be a barrier,

251
00:24:35,840 --> 00:24:39,760
rather than protect,
they are actually giving a false
sense of security

252
00:24:39,760 --> 00:24:43,240
because once the water's
over here, it just keeps going.

253
00:24:45,240 --> 00:24:49,040
The wave here was ten metres high.

254
00:24:49,040 --> 00:24:51,320
The same as the sea wall.

255
00:24:51,320 --> 00:24:55,480
But during the
earthquake, the whole coast had
dropped by about a metre.

256
00:24:55,480 --> 00:24:57,880
so the wall offered little defence.

257
00:25:08,360 --> 00:25:11,680
It looks like the tsunami has
engulfed several cities

258
00:25:11,680 --> 00:25:14,680
in Miyagi Prefecture.

259
00:25:14,680 --> 00:25:19,280
Live footage of Miyagi as
the tsunami has struck the area

260
00:25:19,280 --> 00:25:25,800
obviously engulfing farms, homes,
alongside the river.

261
00:25:25,800 --> 00:25:29,520
In Sendai City, this is,
in Miyagi Prefecture.

262
00:25:29,520 --> 00:25:32,560
SCREAMING

263
00:25:41,880 --> 00:25:47,240
What we are seeing here
is the tsunami front coming in
this bay near Sendai.

264
00:25:47,240 --> 00:25:50,280
You can see this wall of water,
it's not a wave,

265
00:25:50,280 --> 00:25:54,320
but a wall of water
just ploughing through.

266
00:25:54,320 --> 00:25:58,600
You can see minibuses, cars coming
through -

267
00:25:58,600 --> 00:26:02,880
it's a wall of metal and concrete
and timber ploughing forward.

268
00:26:02,880 --> 00:26:08,200
Look at this - there's cars
desperately trying to get out
of the way. It just keeps coming.

269
00:26:08,200 --> 00:26:12,120
The sheer relentless onslaught
of it all is just what's
really striking.

270
00:26:12,120 --> 00:26:16,080
You can see fire, some
building has been set on fire.

271
00:26:16,080 --> 00:26:20,080
The tsunami goes into
these drainage ditches

272
00:26:20,080 --> 00:26:24,840
and look, there's one wave
coming up and look there's another
one coming down.

273
00:26:24,840 --> 00:26:28,120
It's like a pincer movement.

274
00:26:29,840 --> 00:26:32,360
How you could survive that?

275
00:26:32,360 --> 00:26:35,120
And the point is that
this land is so flat,

276
00:26:35,120 --> 00:26:39,720
that this wall of water just
travels inland for ten kilometres.

277
00:26:39,720 --> 00:26:44,080
So those people escaping have
ten kilometres to try to escape.

278
00:26:56,080 --> 00:26:59,120
PANICKED VOICES

279
00:27:16,360 --> 00:27:23,040
These disturbing scenes
show the tsunami striking the
fishing port of Minamisanriku.

280
00:27:23,040 --> 00:27:27,000
They just demonstrate how people
react in the face of disaster.

281
00:27:27,000 --> 00:27:31,960
This is a town of 17,000 people
and you can just see their wooden
houses being swept away.

282
00:27:31,960 --> 00:27:35,280
This community received a warning,

283
00:27:35,280 --> 00:27:39,440
enough warning for people to get up
on to high ground and,
in this case,

284
00:27:39,440 --> 00:27:41,880
film the wave as it comes on.

285
00:27:41,880 --> 00:27:43,440
But many people delayed -

286
00:27:43,440 --> 00:27:46,640
perhaps going back to their
houses to collect possessions

287
00:27:46,640 --> 00:27:51,080
or there little
group here that look as if they
are carrying an elderly relative.

288
00:27:51,080 --> 00:27:55,560
And down in this corner,
a real human drama unfolds.

289
00:27:55,560 --> 00:27:59,440
At first, they
don't seem too concerned,
the water's moving slowly,

290
00:27:59,440 --> 00:28:01,520
and they're moving up the slope,

291
00:28:01,520 --> 00:28:03,760
but very quickly
the wave accelerates

292
00:28:03,760 --> 00:28:07,560
and the pace gets picked up
and suddenly they're right on
the frontline

293
00:28:07,560 --> 00:28:11,000
and the water's just coming across
and speeding up.

294
00:28:11,000 --> 00:28:15,160
And suddenly that's it,
they're trying to escape.

295
00:28:15,160 --> 00:28:19,080
It doesn't matter how many times
you do tsunami drills,

296
00:28:19,080 --> 00:28:24,560
when the terror strikes,
those split second decisions made
in the heat of the moment,

297
00:28:24,560 --> 00:28:27,280
ultimately decide
if you live or die.

298
00:28:36,600 --> 00:28:40,640
Japan was hit by two very
different forces on March 11.

299
00:28:40,640 --> 00:28:46,120
The earthquake they coped
with pretty well. The tsunami
completely overwhelmed them.

300
00:28:53,880 --> 00:28:58,760
The final major wave hit Japan
about three and half hours
after the earthquake.

301
00:29:05,760 --> 00:29:09,480
The same pattern of destruction
was repeated

302
00:29:09,480 --> 00:29:14,360
in countless towns and villages
along hundreds of miles
of coastline.

303
00:29:35,000 --> 00:29:36,840
Some of the towns along these shores

304
00:29:36,840 --> 00:29:40,160
which can trace their history
back over a millennium

305
00:29:40,160 --> 00:29:42,920
had virtually ceased to exist.

306
00:29:56,160 --> 00:29:59,720
The people in Japan get less than a
minute's warning of the earthquake

307
00:29:59,720 --> 00:30:03,000
and maybe 10 to 20 minutes'
warning of the tsunami.

308
00:30:03,000 --> 00:30:06,240
And in both cases,
it just wasn't long enough.

309
00:30:06,240 --> 00:30:10,360
And one question that generation
after generation of geologists

310
00:30:10,360 --> 00:30:14,480
have been wrestling with and one
that absolutely intrigues me is -

311
00:30:14,480 --> 00:30:18,000
why can't we predict earthquakes?

312
00:30:20,920 --> 00:30:23,640
This earthquake happened
in a country

313
00:30:23,640 --> 00:30:27,400
whose huge seismic activity
is the most studied in the world.

314
00:30:31,680 --> 00:30:35,120
Across Japan, more than
1,000 seismic instruments

315
00:30:35,120 --> 00:30:37,840
record each twitch of the ground,

316
00:30:37,840 --> 00:30:42,760
and GPS devices every 20km
track the movement
of the underlying plates.

317
00:30:42,760 --> 00:30:47,720
But even so, nobody was
able to predict when this
earthquake would happen.

318
00:30:55,400 --> 00:30:59,320
But there's one place in the world
where scientists really thought

319
00:30:59,320 --> 00:31:02,520
they were getting close to the holy
grail of earthquake prediction.

320
00:31:04,640 --> 00:31:07,800
This line of hills with
the trench cut through the middle

321
00:31:07,800 --> 00:31:10,600
is the San Andreas Fault
in California.

322
00:31:15,160 --> 00:31:19,480
The world's biggest attempt
to try to predict earthquakes
took place here.

323
00:31:21,320 --> 00:31:24,760
In a small town on the fault,
there seemed to be a pattern

324
00:31:24,760 --> 00:31:27,320
of earthquakes occurring
at regular intervals.

325
00:31:28,320 --> 00:31:31,640
Scientists hoped they could
predict the next one

326
00:31:31,640 --> 00:31:35,880
by spotting telltale clues
in the movement of the ground.

327
00:31:40,080 --> 00:31:41,760
This is Parkfield.

328
00:31:44,840 --> 00:31:49,280
26 years ago, it seemed this
insignificant dot on the map

329
00:31:49,280 --> 00:31:52,280
held the key
to predicting earthquakes.

330
00:31:53,920 --> 00:31:58,200
It began when a team of geologists
noticed something unusual here.

331
00:31:58,200 --> 00:32:02,520
Parkfield had been repeatedly
struck by earthquakes.

332
00:32:04,640 --> 00:32:09,600
It was in the '70s and early '80s,
it was recognised

333
00:32:09,600 --> 00:32:13,520
that there was a sequence
of magnitude-six earthquakes

334
00:32:13,520 --> 00:32:17,200
that repeated the same stretch
of the San Andreas Fault

335
00:32:17,200 --> 00:32:19,520
every 20-odd years.

336
00:32:19,520 --> 00:32:22,840
It didn't take too much imagination
to extrapolate

337
00:32:22,840 --> 00:32:25,680
and say, "OK, the next one
ought to be in the late '80s."

338
00:32:29,400 --> 00:32:33,200
In 1985, geologists began setting
up hundreds of instruments here

339
00:32:33,200 --> 00:32:36,680
to track the build-up
to the next quake.

340
00:32:36,680 --> 00:32:42,880
They believed it would occur
some time between 1987 and 1993.

341
00:32:42,880 --> 00:32:49,400
Well, what you're hoping to see -
the analogy is a stick breaking.

342
00:32:49,400 --> 00:32:52,800
So, in the long term,
you're bending the stick,

343
00:32:52,800 --> 00:32:59,000
you see it deform, and then maybe
just before the stick goes "snap",

344
00:32:59,000 --> 00:33:02,080
you'll hear "crack, crack, crack"
or something like that.

345
00:33:03,320 --> 00:33:05,560
Now they had narrowed down
the time window

346
00:33:05,560 --> 00:33:08,560
and knew where
it was going to strike,

347
00:33:08,560 --> 00:33:12,640
this was science's best chance to
see the build-up to an earthquake.

348
00:33:12,640 --> 00:33:16,200
Millions of dollars flooded in
to fund the research.

349
00:33:16,200 --> 00:33:20,040
All they had to do now
was just sit and wait.

350
00:33:22,240 --> 00:33:25,880
We had some creepmeters
that measure fault slip,

351
00:33:25,880 --> 00:33:30,240
some geochemical experiments, strain
meters, global positioning system.

352
00:33:31,960 --> 00:33:36,080
1993 came and went
with no earthquake.

353
00:33:36,080 --> 00:33:39,320
So did 1994,

354
00:33:39,320 --> 00:33:41,480
'95

355
00:33:41,480 --> 00:33:43,960
and '96.

356
00:33:46,240 --> 00:33:50,640
Our guess was basically -
what'll we call it?

357
00:33:50,640 --> 00:33:53,200
Ambitious or optimistic.

358
00:33:56,320 --> 00:34:00,080
In fact, the earthquake
didn't happen until 2004.

359
00:34:00,080 --> 00:34:03,040
And then it struck without warning.

360
00:34:05,320 --> 00:34:09,200
Whatever the trigger,
it had eluded the instruments.

361
00:34:11,960 --> 00:34:14,240
Despite all their efforts,
the geologists

362
00:34:14,240 --> 00:34:17,280
had failed to spot
any telltale clues.

363
00:34:22,840 --> 00:34:25,240
It was like the fault
was quiet, quiet, quiet.

364
00:34:25,240 --> 00:34:26,960
And then it broke.

365
00:34:26,960 --> 00:34:30,880
And it was a fairly negative result.

366
00:34:30,880 --> 00:34:33,120
We were waiting
to catch that precursor

367
00:34:33,120 --> 00:34:37,320
with all these instruments,
and nothing happened.

368
00:34:42,320 --> 00:34:44,520
The failure of
the Parkfield experiment

369
00:34:44,520 --> 00:34:46,920
was a significant moment
in earthquake science.

370
00:34:48,480 --> 00:34:50,880
Earthquakes are sensitive
to small triggers

371
00:34:50,880 --> 00:34:53,280
far below the surface of the planet,

372
00:34:53,280 --> 00:34:55,280
too far down to be measured.

373
00:34:56,560 --> 00:34:58,600
After Parkfield,
trying to spot clues

374
00:34:58,600 --> 00:35:03,280
to when an earthquake would happen
seemed too simplistic.

375
00:35:07,720 --> 00:35:10,880
In Japan, events were
to push earthquake science

376
00:35:10,880 --> 00:35:13,200
in a very different direction.

377
00:35:13,200 --> 00:35:16,960
The catalyst was another
failure of prediction.

378
00:35:28,400 --> 00:35:32,880
In 1995, the city of Kobe
was devastated by an earthquake.

379
00:35:36,880 --> 00:35:39,000
6,000 people were killed.

380
00:35:43,480 --> 00:35:46,360
The disaster was so significant
for science

381
00:35:46,360 --> 00:35:49,280
because no-one had thought
the city was at risk.

382
00:35:50,320 --> 00:35:53,920
Now the most urgent task was
to identify which other areas

383
00:35:53,920 --> 00:35:56,680
of the country were most threatened
by earthquakes.

384
00:36:03,000 --> 00:36:04,920
To try to find out where,

385
00:36:04,920 --> 00:36:09,600
Japanese scientists began to place
hi-tech seismometers all over Japan

386
00:36:09,600 --> 00:36:13,360
to try and detect the slightest
little movements of the ground.

387
00:36:13,360 --> 00:36:16,120
Alongside, they placed GPS devices

388
00:36:16,120 --> 00:36:19,120
to track the build-up of strain
in the rocks below,

389
00:36:19,120 --> 00:36:22,680
and after all this work,
this is what they came up with -

390
00:36:22,680 --> 00:36:25,520
the earthquake hazard map of Japan.

391
00:36:25,520 --> 00:36:28,400
The thing about what
this map represents

392
00:36:28,400 --> 00:36:31,800
is really where earthquake science
is in Japan today,

393
00:36:31,800 --> 00:36:36,040
because what it shows is
the areas that are most at risk

394
00:36:36,040 --> 00:36:38,160
of being affected by an earthquake,

395
00:36:38,160 --> 00:36:40,560
with those that are most vulnerable
coded red.

396
00:36:40,560 --> 00:36:43,600
Now, this map was made
in 2010, just last year,

397
00:36:43,600 --> 00:36:47,680
but you can see one of those red
danger zones is right here - Sendai,

398
00:36:47,680 --> 00:36:52,160
which is the city that was closest
to the earthquake on March 11.

399
00:36:52,160 --> 00:36:57,880
So, can we predict when the next
big earthquake will strike? No.

400
00:36:57,880 --> 00:37:01,760
But can we forecast the areas
that will need to prepare for one?

401
00:37:01,760 --> 00:37:03,480
Yeah, I think we can.

402
00:37:03,480 --> 00:37:06,320
And that is a big advance.

403
00:37:08,880 --> 00:37:11,720
'Professor John McCloskey
is pushing the boundaries

404
00:37:11,720 --> 00:37:16,320
'of this kind of forecasting in
another of the world's seismic
danger zones.'

405
00:37:16,320 --> 00:37:20,520
In Sumatra, we have
the pieces of the jigsaw puzzle

406
00:37:20,520 --> 00:37:24,560
which will allow us ultimately
not to predict earthquakes,

407
00:37:24,560 --> 00:37:27,440
but to be able to say that
there are certain sections

408
00:37:27,440 --> 00:37:31,320
of these fault systems
which are more likely to fail

409
00:37:31,320 --> 00:37:34,280
in the next ten years
than any other sections.

410
00:37:34,280 --> 00:37:37,040
But I think we will globally
be able to identify

411
00:37:37,040 --> 00:37:39,400
a series of earthquake hot spots.

412
00:37:39,400 --> 00:37:43,720
We won't be able to say when the
next earthquakes will happen there,

413
00:37:43,720 --> 00:37:46,720
but we will be able
to identify earthquakes

414
00:37:46,720 --> 00:37:50,400
or places that will
give us earthquakes
of magnitude eight or bigger,

415
00:37:50,400 --> 00:37:53,120
that will produce
really damaging shaking,

416
00:37:53,120 --> 00:37:57,120
that will produce secondary hazards
like tsunamis and landslides

417
00:37:57,120 --> 00:38:01,640
and that will be potentially
absolutely lethal for populations.

418
00:38:01,640 --> 00:38:06,800
So earthquake science is working
today in the absence of prediction...

419
00:38:06,800 --> 00:38:12,280
Yeah. ..to help people prepare and
to survive future big earthquakes.

420
00:38:12,280 --> 00:38:16,880
'Of course, preparation
for natural disaster

421
00:38:16,880 --> 00:38:19,560
'is all about knowing
what risks to expect.'

422
00:38:22,240 --> 00:38:25,880
But in Japan, what started
as a natural disaster

423
00:38:25,880 --> 00:38:28,720
unexpectedly became a man-made one.

424
00:38:34,040 --> 00:38:36,640
In one small part of the coast,

425
00:38:36,640 --> 00:38:40,600
the crisis was entering
a new critical phase.

426
00:38:44,920 --> 00:38:50,000
A battle was on to stop radiation
escaping from this power station.

427
00:39:00,480 --> 00:39:03,320
Immediately after the earthquake,
seismic sensors

428
00:39:03,320 --> 00:39:06,440
had automatically triggered
the shutdown

429
00:39:06,440 --> 00:39:08,840
of four nuclear power stations
across Japan.

430
00:39:08,840 --> 00:39:15,800
Among them was the Fukushima No.1
plant, 240km from Tokyo.

431
00:39:17,360 --> 00:39:21,960
It's standard procedure after
an earthquake to insert control rods

432
00:39:21,960 --> 00:39:26,360
into the core of a reactor
to stop the nuclear chain reaction.

433
00:39:26,360 --> 00:39:29,560
But elsewhere in the plant,
there was a problem.

434
00:39:29,560 --> 00:39:32,960
The earthquake had knocked out
the power supply

435
00:39:32,960 --> 00:39:34,760
to the reactor's cooling system.

436
00:39:36,560 --> 00:39:39,480
Looking at this map,
you find yourself wondering

437
00:39:39,480 --> 00:39:42,560
why anyone would build
a nuclear power plant in Japan,

438
00:39:42,560 --> 00:39:46,480
a country with nearly
a third of the world's earthquakes.

439
00:39:46,480 --> 00:39:49,960
You can see them all here
in red dots scattered along.

440
00:39:49,960 --> 00:39:54,000
There you can see the outline of
Japan with the nuclear power plants.

441
00:39:54,000 --> 00:39:57,400
It's a decision that's been
forced on them by geology,

442
00:39:57,400 --> 00:40:00,240
because this is a nation
with a real thirst for energy

443
00:40:00,240 --> 00:40:03,280
and yet no real oil or gas
of its own.

444
00:40:03,280 --> 00:40:08,080
It's got 17 nuclear power plants
dotted around the coastline

445
00:40:08,080 --> 00:40:10,640
because they need
massive amounts of water.

446
00:40:10,640 --> 00:40:13,480
Of course, the coastline
is where people live,

447
00:40:13,480 --> 00:40:17,600
so it's an example, really, of
an uneasy bargain that's been struck

448
00:40:17,600 --> 00:40:20,160
between people and the planet.

449
00:40:22,960 --> 00:40:26,400
But Japan's engineers prided
themselves on having made

450
00:40:26,400 --> 00:40:29,000
their nuclear power stations
quake-proof.

451
00:40:30,800 --> 00:40:34,520
This reactor complex you can
see them - one, two, three, four -

452
00:40:34,520 --> 00:40:36,760
was built with earthquakes in mind.

453
00:40:36,760 --> 00:40:41,160
It was designed to withstand
a magnitude 7.9 shake.

454
00:40:41,160 --> 00:40:42,760
With the sea just here,

455
00:40:42,760 --> 00:40:46,880
they built a sea wall 6m high
to protect against tsunamis.

456
00:40:46,880 --> 00:40:49,960
But what they didn't plan for
was an earthquake so big

457
00:40:49,960 --> 00:40:52,120
or a tsunami so high.

458
00:40:52,120 --> 00:40:54,960
If that wall had just been
1.5m higher,

459
00:40:54,960 --> 00:40:56,600
it would have kept the wave out.

460
00:40:56,600 --> 00:41:01,840
But as it was,
it overtopped it and set off
a terrifying chain of events.

461
00:41:02,720 --> 00:41:07,080
What this represents is a
catastrophic failure of imagination.

462
00:41:09,160 --> 00:41:12,640
The earthquake had severed the
power supply to the cooling system.

463
00:41:12,640 --> 00:41:15,880
Then the tsunami
swept over the sea wall

464
00:41:15,880 --> 00:41:18,920
and destroyed the backup generators.

465
00:41:18,920 --> 00:41:21,680
Now the engineers were
forced to rely on batteries

466
00:41:21,680 --> 00:41:23,480
to run the cooling system.

467
00:41:23,480 --> 00:41:26,400
And these had just
eight hours' life.

468
00:41:26,400 --> 00:41:29,480
When THEY ran out,
the cooling system died.

469
00:41:38,200 --> 00:41:41,640
Although the main nuclear
chain reaction had been stopped,

470
00:41:41,640 --> 00:41:43,480
when atoms of uranium
are split,

471
00:41:43,480 --> 00:41:48,080
other radioactive elements, like
iodine and caesium, are released.

472
00:41:48,080 --> 00:41:51,120
As they decay, they create heat.

473
00:41:51,120 --> 00:41:53,080
Without a cooling system,

474
00:41:53,080 --> 00:41:55,880
there's nothing to stop
the reactor overheating.

475
00:42:00,440 --> 00:42:04,520
A day later, an explosion
blew away much of the roof

476
00:42:04,520 --> 00:42:08,280
and outer walls of
reactor number one.

477
00:42:09,280 --> 00:42:14,880
As the fuel rods heated up,
the cladding around them reacted

478
00:42:14,880 --> 00:42:18,320
with steam and produced
hydrogen gas.

479
00:42:18,320 --> 00:42:21,840
The gas exploded, propelling
radioactive elements

480
00:42:21,840 --> 00:42:23,960
into the atmosphere.

481
00:42:29,400 --> 00:42:32,360
Then explosions hit
two other reactors,

482
00:42:32,360 --> 00:42:37,000
and levels of radioactivity
around the plant rose.

483
00:42:40,080 --> 00:42:44,080
Now Japan and the world were haunted
by uncertainty.

484
00:42:44,080 --> 00:42:48,120
Just how dangerous was the
radiation that been released?

485
00:42:50,520 --> 00:42:54,880
In this nation, radiation evokes
a particular dread.

486
00:42:56,400 --> 00:42:59,480
As fear spread, hundreds
of thousands of people

487
00:42:59,480 --> 00:43:02,480
living near the plant
were evacuated.

488
00:43:02,480 --> 00:43:06,320
Some governments advised their
nationals to leave the country.

489
00:43:07,320 --> 00:43:12,280
But it was the workers
who stayed behind at the plant
that were most at risk.

490
00:43:12,280 --> 00:43:17,280
Some have been exposed to very high
levels of radiation.

491
00:43:17,280 --> 00:43:21,800
Their ongoing struggle to keep
the reactors cool is heroic.

492
00:43:21,800 --> 00:43:27,560
But the continuing inability to
bring the plant under control

493
00:43:27,560 --> 00:43:30,000
has only fuelled anxiety.

494
00:43:31,000 --> 00:43:34,280
I wanted to ask
Professor Jim Al-Khalili,

495
00:43:34,280 --> 00:43:35,880
a nuclear physicist,

496
00:43:35,880 --> 00:43:40,360
just how dangerous this release
of radioactivity was.

497
00:43:40,360 --> 00:43:43,360
The caesium and the iodine,
I mean, what can they do to you?

498
00:43:43,360 --> 00:43:47,480
Both iodine 131 and caesium 137,

499
00:43:47,480 --> 00:43:51,080
if you breathe them in, or you ingest
them through food or through water,

500
00:43:51,080 --> 00:43:54,640
and they collect inside the body,
the particles they spit out,

501
00:43:54,640 --> 00:43:58,600
can damage cells,
can even cause cancer.

502
00:43:58,600 --> 00:44:01,680
I've been hearing about these
plant workers getting doses

503
00:44:01,680 --> 00:44:06,520
of 400 millisieverts per hour and
sometimes an instance of 10,000,

504
00:44:06,520 --> 00:44:09,000
I mean what are these units?
What do they mean?

505
00:44:09,000 --> 00:44:12,240
The sievert, or the millisievert in
this case, is a unit of measurement.

506
00:44:12,240 --> 00:44:16,680
It tells the level of exposure
to the radiation that we have.

507
00:44:16,680 --> 00:44:21,040
I think it's very useful to compare
it with how much radiation

508
00:44:21,040 --> 00:44:23,920
we're exposed to otherwise normally.

509
00:44:23,920 --> 00:44:28,040
So if you think the base level,
no radiation is zero,

510
00:44:28,040 --> 00:44:32,200
all of us are exposed to natural
background radiation

511
00:44:32,200 --> 00:44:35,600
of about two millisieverts, OK.

512
00:44:35,600 --> 00:44:38,800
So that's what we get from the
atmosphere, from the food we eat,

513
00:44:38,800 --> 00:44:42,360
coming up from the ground.
If you have a CT scan,

514
00:44:42,360 --> 00:44:46,800
then that will give you something
like ten millisieverts.

515
00:44:46,800 --> 00:44:49,640
So you don't want to
have too many of those.

516
00:44:49,640 --> 00:44:55,400
A typical nuclear worker would
have a safety margin of about
20 millisieverts per year.

517
00:44:55,400 --> 00:44:59,520
Per year? So 400 millisieverts an
hour is somewhere away over there?

518
00:44:59,520 --> 00:45:03,240
Is way over there, absolutely. Yes,
that's where the concern is.

519
00:45:03,240 --> 00:45:07,280
What about the wider community? I
mean, how concerned should they be?

520
00:45:07,280 --> 00:45:11,080
Well, I think it's important to
understand just how far this

521
00:45:11,080 --> 00:45:13,320
the radiation will extend.

522
00:45:13,320 --> 00:45:17,600
So this is the Japanese government's
imposed exclusion zones.

523
00:45:17,600 --> 00:45:22,280
So the plant is here and you have a
20 kilometre radius exclusion zone

524
00:45:22,280 --> 00:45:27,720
and the 30 kilometres outside it.
Beyond the exclusion zone,

525
00:45:27,720 --> 00:45:31,720
the risk is very, very low,
it's negligible. It's no higher than

526
00:45:31,720 --> 00:45:34,880
natural and you can compare it with
just natural radiation,

527
00:45:34,880 --> 00:45:38,400
depending on what part of the world
you live in.

528
00:45:38,400 --> 00:45:43,760
The worry is how far the air will
carry this radioactive material,

529
00:45:43,760 --> 00:45:49,320
the plume, and as far as we know,
it was travelling out east

530
00:45:49,320 --> 00:45:51,600
into the Pacific, not inland.

531
00:45:51,600 --> 00:45:54,280
But some radioactive fallout
has come on land, hasn't it?

532
00:45:54,280 --> 00:45:57,240
Because there's been talk of
iodine in the water in Tokyo.

533
00:45:57,240 --> 00:46:00,120
We have to remember this is the other
way that this radioactivity

534
00:46:00,120 --> 00:46:02,480
can spread, other than
just through the air.

535
00:46:02,480 --> 00:46:05,800
If it gets into the water supply,
it can get into the food chain,

536
00:46:05,800 --> 00:46:09,160
then that's the way that
the Japanese population

537
00:46:09,160 --> 00:46:12,240
might ingest it and that
is cause for some concern.

538
00:46:12,240 --> 00:46:15,120
And how much concern then,
iodine in the water?

539
00:46:15,120 --> 00:46:18,040
Well, I think, we've heard that
what they measured was

540
00:46:18,040 --> 00:46:22,400
that the level was higher
than what might be deemed
safe for young children.

541
00:46:22,400 --> 00:46:25,520
But iodine has a half-life
of just eight days,

542
00:46:25,520 --> 00:46:29,520
and so eight days from now, the level
drops to half of what it was before,

543
00:46:29,520 --> 00:46:32,440
so it very quickly drops down
to manageable and safe levels.

544
00:46:32,440 --> 00:46:37,720
But it's not sounding as if this
is a kind of no-go Chernobyl-type
disaster zone at all?

545
00:46:37,720 --> 00:46:41,320
No, I mean, we certainly know
this isn't a Chernobyl.

546
00:46:41,320 --> 00:46:44,360
So, basically, we've got to
keep this into perspective?

547
00:46:44,360 --> 00:46:49,080
It's certainly a major public concern
and we understand that

548
00:46:49,080 --> 00:46:53,000
people are afraid of radiation -
it's invisible, it can cause cancer,

549
00:46:53,000 --> 00:46:56,040
of course there are worries.
But people need to understand

550
00:46:56,040 --> 00:46:59,440
the real risks and, yes,
keep things in perspective.

551
00:47:01,960 --> 00:47:06,480
What this disaster illustrates
so starkly is a failure to plan

552
00:47:06,480 --> 00:47:09,320
for events that nobody
wants to imagine.

553
00:47:09,320 --> 00:47:11,440
But when it comes to
nuclear power,

554
00:47:11,440 --> 00:47:13,240
the stakes could not be higher

555
00:47:13,240 --> 00:47:15,880
in that bargain we strike
with the planet.

556
00:47:18,040 --> 00:47:20,080
You know this isn't
the first time that

557
00:47:20,080 --> 00:47:22,920
a Japanese nuclear power plant has
been breached during an earthquake.

558
00:47:22,920 --> 00:47:27,360
In 2007, a magnitude
6.6 seismic jolt

559
00:47:27,360 --> 00:47:29,240
struck the country's largest plant

560
00:47:29,240 --> 00:47:33,520
and caused a minor radioactive leak,
and around the world

561
00:47:33,520 --> 00:47:37,160
the 440 odd nuclear power plants,
something like a fifth

562
00:47:37,160 --> 00:47:42,040
lie in these seismically
active areas.

563
00:47:42,040 --> 00:47:48,800
So if we think that we can design
for earthquakes, these are
going to be the ultimate test.

564
00:47:59,760 --> 00:48:05,800
The triple calamity of the past
two weeks - earthquake, tsunami

565
00:48:05,800 --> 00:48:07,480
and threat of nuclear meltdown -

566
00:48:07,480 --> 00:48:11,360
have left this country
in a state of shock.

567
00:48:11,360 --> 00:48:15,040
The scale of the human tragedy
is only just sinking in.

568
00:48:15,040 --> 00:48:19,840
10,000 killed, over 17,000 missing,

569
00:48:19,840 --> 00:48:22,960
an estimated half a million
displaced.

570
00:48:22,960 --> 00:48:27,440
This has become the most recorded
earthquake in history,

571
00:48:27,440 --> 00:48:30,600
and it's set to be
the most studied.

572
00:48:31,920 --> 00:48:37,760
Scientists of all disciplines
are starting to analyse this
disaster in incredible detail.

573
00:48:37,760 --> 00:48:41,600
And the hope is that that work will
ensure that next time

574
00:48:41,600 --> 00:48:45,680
what begins as a geological event
somewhere in the world

575
00:48:45,680 --> 00:48:48,120
won't end up such a human tragedy.

576
00:48:51,120 --> 00:48:57,760
One of the most pressing questions
that researchers are already trying
to answer is this -

577
00:48:57,760 --> 00:49:03,040
what is happening to the tectonic
plates across the world in the
aftermath of the earthquake?

578
00:49:07,400 --> 00:49:11,440
A lot of people have been asking me
about whether the earthquake that
happened in Japan

579
00:49:11,440 --> 00:49:14,840
has got anything to do with
the quake that struck
Christchurch last month.

580
00:49:14,840 --> 00:49:17,880
Is it part of a seismic
chain reaction?

581
00:49:17,880 --> 00:49:21,000
On a global scale, no,
I don't think they're related,

582
00:49:21,000 --> 00:49:22,120
but on a local scale,

583
00:49:22,120 --> 00:49:25,480
we already know that one earthquake
can affect another,

584
00:49:25,480 --> 00:49:29,360
and we know that the March 11th
quake was triggered by stress

585
00:49:29,360 --> 00:49:33,200
that shifted from another smaller
quake just a couple of days before.

586
00:49:33,200 --> 00:49:37,240
The question that geologists
are really trying to get
to grips with is

587
00:49:37,240 --> 00:49:40,840
could the events of the last
two weeks be the trigger
for another earthquake,

588
00:49:40,840 --> 00:49:45,720
perhaps Japan's big one,
one directly under Tokyo?

589
00:49:53,200 --> 00:49:57,640
Over 30 million people live in
and around Tokyo,

590
00:49:57,640 --> 00:50:00,840
a quarter of the country's
population.

591
00:50:00,840 --> 00:50:05,560
An earthquake centred
on this city is what the
Japanese call the big one.

592
00:50:07,000 --> 00:50:13,280
And it's such fear today because of
what happened to this city in 1923.

593
00:50:20,680 --> 00:50:24,360
On September 1st,
shortly before midday,

594
00:50:24,360 --> 00:50:28,240
Tokyo was struck by
a large earthquake.

595
00:50:28,240 --> 00:50:33,880
The ground shook for at
least four minutes, bringing
down swathes of the city.

596
00:50:33,880 --> 00:50:39,480
It claimed over 100,000 lives and
left almost 2 million without homes.

597
00:50:39,480 --> 00:50:41,000
But here's the thing,

598
00:50:41,000 --> 00:50:46,280
this earthquake is estimated to have
measured 7.9 on the magnitude scale,

599
00:50:46,280 --> 00:50:50,520
more than ten times smaller than
the earthquake two weeks ago.

600
00:50:55,880 --> 00:50:59,800
The question of how the recent
earthquake might now affect Tokyo

601
00:50:59,800 --> 00:51:02,720
is one that John McCloskey
is studying.

602
00:51:04,280 --> 00:51:07,720
He's produced a very revealing map

603
00:51:07,720 --> 00:51:10,920
showing what's happened under Japan 
since the earthquake.

604
00:51:12,280 --> 00:51:16,400
It displays changes in stress levels
deep under ground.

605
00:51:17,200 --> 00:51:20,760
So the blue area is where the stress
has been released,

606
00:51:20,760 --> 00:51:24,440
stress has dropped down,
and the red area is where
the stress has gone up.

607
00:51:24,440 --> 00:51:29,200
So what we left with is a picture of
areas that are blue,

608
00:51:29,200 --> 00:51:34,120
in which the stress has dropped,
and, therefore, the risk of other
earthquakes

609
00:51:34,120 --> 00:51:39,000
has probably dropped. And red areas,
where the stress has increased

610
00:51:39,000 --> 00:51:42,960
and the risk of other earthquakes
has increased accordingly.

611
00:51:42,960 --> 00:51:47,600
It's looking as if a lot
of the stress increase
is around the area to the south,

612
00:51:47,600 --> 00:51:49,400
and that's the area of Tokyo then.

613
00:51:49,400 --> 00:51:52,720
That's absolutely true because most
of the slip happened up here,

614
00:51:52,720 --> 00:51:56,680
most of the interaction stress
is forced towards the south.

615
00:51:56,680 --> 00:52:01,880
That is evidenced by the hundreds
of aftershocks that have happened
in this area.

616
00:52:01,880 --> 00:52:04,720
So is it fair to say that
the big earthquake in the north

617
00:52:04,720 --> 00:52:09,040
has increased the risk
of an earthquake in the south?

618
00:52:09,040 --> 00:52:12,360
The big earthquake in the north
is already increasing the risk.

619
00:52:12,360 --> 00:52:15,680
It is already generating
earthquakes in the south.

620
00:52:15,680 --> 00:52:20,280
Magnitude 7.9 earthquake is
a direct result of the stress

621
00:52:20,280 --> 00:52:22,720
shed from this earthquake
in this region.

622
00:52:22,720 --> 00:52:24,640
This is already happening.

623
00:52:25,640 --> 00:52:29,880
It's early days,
the data are still coming in,

624
00:52:29,880 --> 00:52:32,400
but it does seem like
the recent earthquake

625
00:52:32,400 --> 00:52:36,920
makes the possibility of a big quake
in Tokyo more likely.

626
00:52:51,960 --> 00:52:55,840
Facing up to the threat of
earthquakes is vital.

627
00:53:00,960 --> 00:53:05,400
And for me, it's not about
predicting when they will happen.

628
00:53:05,400 --> 00:53:09,200
It's about how you protect yourself
for when they arrive.

629
00:53:11,200 --> 00:53:13,800
When I was in Tokyo a few years ago,

630
00:53:13,800 --> 00:53:18,800
I saw the latest innovations
in earthquake-proofing
the city's buildings.

631
00:53:21,480 --> 00:53:27,800
Normally the rigid walls of tall
buildings will shatter under the
pressure of a big earthquake.

632
00:53:27,800 --> 00:53:35,040
But in Japan, special features are
added to absorb these forces and
make the superstructure flexible.

633
00:53:35,040 --> 00:53:42,360
Here at Tokyo's Nihon University,
bendable braces have been designed
for this laboratory building.

634
00:53:43,360 --> 00:53:48,320
Professor Masao Saito is the
earthquake engineer responsible.

635
00:53:48,320 --> 00:53:52,760
Can you tell me about the
system you have got here to
reduce earthquake shaking?

636
00:53:52,760 --> 00:53:57,200
These bracing system are arranged
along the whole wall.

637
00:53:57,200 --> 00:54:01,720
So you have this bracing system
all along the wall.

638
00:54:01,720 --> 00:54:08,600
Hundreds of these braces ensure the
laboratory is twice as flexible as
a conventional building.

639
00:54:08,600 --> 00:54:11,240
I'll show you through this model.

640
00:54:11,240 --> 00:54:13,280
As Professor Saito's model shows,

641
00:54:13,280 --> 00:54:16,720
when an earthquake hits,
each brace contains a piston,

642
00:54:16,720 --> 00:54:19,200
which acts like a shock absorber.

643
00:54:21,000 --> 00:54:27,160
If the frames moves, the
piston works in this direction.

644
00:54:27,160 --> 00:54:30,520
So it's dampening down everything.
Dampening here.

645
00:54:30,520 --> 00:54:32,520
Beautiful.

646
00:54:35,320 --> 00:54:38,680
So amidst all the tragedy
of the past few weeks,

647
00:54:38,680 --> 00:54:41,200
there's on image that
I think holds hope.

648
00:54:41,200 --> 00:54:45,640
This building swaying in the
earthquake, but remaining standing.

649
00:54:45,640 --> 00:54:51,360
Japan leads the world
in designing buildings that
can survive earthquakes.

650
00:54:55,120 --> 00:55:00,920
Sure it's terrifying to be inside
one when a quake strikes,

651
00:55:00,920 --> 00:55:04,200
but the simple fact is that in many
parts of the world

652
00:55:04,200 --> 00:55:08,040
these sorts of shocks would reduce
a building to rubble.

653
00:55:11,200 --> 00:55:13,640
Things could have been
very different in Japan

654
00:55:13,640 --> 00:55:17,720
if the earthquake had struck not
offshore, but under a major city.

655
00:55:17,720 --> 00:55:20,280
The thing is, this was a huge
earthquake and, actually,

656
00:55:20,280 --> 00:55:23,200
comparatively few buildings
fell down.

657
00:55:23,200 --> 00:55:26,760
And that's the point, really. It's
possible to engineer structures

658
00:55:26,760 --> 00:55:29,960
not to fall down in earthquakes
and that more than anything else

659
00:55:29,960 --> 00:55:32,640
is what we've got to take forward.

660
00:55:35,440 --> 00:55:41,480
Ten of the 20 largest cities
in the world are located
in seismic danger zones.

661
00:55:43,240 --> 00:55:46,360
For the millions of people living
on tectonic boundaries,

662
00:55:46,360 --> 00:55:49,640
the risk of earthquakes
is inescapable.

663
00:55:51,280 --> 00:55:55,000
The hope has to be that
we'll build our cities better

664
00:55:55,000 --> 00:55:57,400
to help people survive them.

665
00:56:01,520 --> 00:56:05,800
We know where the world's most
lethal earthquake zones are.

666
00:56:05,800 --> 00:56:10,040
And in the major cities that
lie along them, we know where
the big danger areas are.

667
00:56:10,040 --> 00:56:15,840
It's true that we can't predict
earthquakes but we can anticipate
them and we can build for them.

668
00:56:15,840 --> 00:56:19,680
For me, what the events of the last
two weeks have really brought home

669
00:56:19,680 --> 00:56:26,360
is that we need to continue to spend
time, money and effort preparing for
the looming seismic threats ahead.

670
00:56:26,360 --> 00:56:29,000
It really is the only way forward.

671
00:56:44,160 --> 00:56:46,240
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672
00:56:46,240 --> 00:56:48,320
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