[narrator] We have uncovered
a remarkable planet,
a world of extreme weather,
alien landscapes,
and bizarre phenomena.
It's the most complex system
we know of in the universe.
That planet
is Earth,
and we are only beginning
to unlock its secrets.
At sea, the wave
is virtually invisible,
but it has a secret.
[man] It can travel
at 600 miles per hour.
[narrator] And it's headed
straight for shore.
What would happen if it hit
one of the United States'
most popular cities?
Generated by cataclysm,
and with the power to kill
hundreds of thousands,
tsunamis decoded
on Secrets of the Earth.
For mankind,
the oceans of planet Earth
are treasured resources,
but they have a dark side.
Periodically, they erupt
in violent tsunamis.
90% of them are triggered by
strong undersea earthquakes.
[rumbling]
[man] When you think
of a tsunami,
you have to think
of a wall of water
with the strength
of a wall of bricks.
[narrator] They are
fundamentally different
from all other waves
in the sea.
A magnitude-9.0 earthquake
strikes Japan.
It hurled a tsunami
toward Tohoku Province,
pushing water in some places
120 feet high.
Eighteen thousand people killed
or missing,
6,000 injured,
$235 billion in damage.
Earth's most expensive
natural disaster.
Kesennuma is a small city
300 miles north of Tokyo.
It's home
to a tuna fishing fleet
hard-hit by the tsunami.
[man] This ship is more than
a mile inland.
This is a tuna ship that used
to be in Kesennuma Harbor,
and the tsunami came
and it floated all the way here.
[narrator]
Japan sits on the edge
of Earth's Ring of Fire,
a belt of earthquake faults
and volcanoes
encircling the Pacific.
Fourteen fatal tsunamis
in the past century
make Japan this world's most
tsunami-prone country,
but it is far from alone.
An offshore earthquake
could trigger a tsunami
in the northwest United States.
[Kaku] Take a look at
the Cascadia fault,
going from Canada
down to Washington State
down to Oregon.
We know that it's ruptured
in the past.
[narrator] Mud cores
taken from the seafloor
hold evidence for tsunamis
throughout the past.
[man] Tsunamis
have been occurring
for millions
and millions of years,
as long as the Earth
has had oceans.
[narrator] A Cascadia fault
tsunami left behind sediment
scientists can date
to the year 1700.
Stories of a great earthquake
followed by flood waters
exist in the oral traditions of
Native Americans in the area.
And tree ring studies reveal
stands of dead trees
with outermost rings
dating to 1699,
the last growing season
before the tsunami.
A precise date comes from
a secret source.
[Kaku] By going to Japan,
they found records
of an ancient tsunami
of the year 1700.
Therefore, we now realize that
that very same tsunami
that hit the United States
back then also hit Japan.
We know the exact date
and the exact hour
that the tsunami hit.
[narrator]
The Japanese records tell us
the tsunami struck
the American Northwest
on Tuesday,
January 26th, 1700,
at 9 p.m.
In Japan today,
scientist Costas Synolakis
revisits the scene
of the Tohoku tsunami.
He is one of 300 scientists
who surveyed
the initial damage.
The stranded tuna ship
stands as a monument
and still reveals surprises.
Shh.
What is this?
My God, heh.
Do you see that?
That's a car.
The ship is sitting
on top of the car.
When I was here,
the debris was about higher
than where I'm standing,
so you couldn't see this.
[narrator] The 330-ton
Kyotoku Maru Number 18
is propped up across Route 210.
It's surrounded by
the foundations of buildings
that the water washed away.
The tsunami here began
as most of them do,
with a violent shift
of the ocean's bed.
[Kaku] If I have an earthquake,
and I have a fault subduction
that goes like this,
then the sudden vaulting
of the ocean floor
can cause a uplifting
of the water,
which creates a tsunami.
[narrator] When a large
earthquake strikes
under the seafloor,
it can jolt
35 billion gallons of water
into motion.
Yet, in the open ocean,
a tsunami wave
has so much room to spread out,
it may only be a few feet high.
[Kaku] If you're an ocean liner,
and a tsunami goes by you
in the middle of the Pacific,
you hardly notice it.
But as the wave
gets toward shore,
the shoreline starts to get
thinner and thinner,
meaning that water is pushed
upwards as a consequence.
And that's why tsunamis can have
such a devastating effect
as they go toward the shoreline.
[narrator] Originating
just 60 miles offshore,
the Tohoku earthquake
shoved Japan's coast
200 feet to the east.
The movement
of the Earth's crust
redistributed the entire
planet's weight.
This shifted the Earth's axis
by 4 inches,
possibly shortening our day
by millionths of a second.
December 26, 2004.
An underwater earthquake
strikes
off the Indonesian island
of Sumatra,
sending a tsunami
across the Indian Ocean.
The killer waves bring
strange stories with them.
Witnesses say animals sense
the oncoming disaster.
Elephants flee from the coast.
Flamingoes abandon
their nesting grounds.
Scuba divers underwater
are unaware of the disaster.
After surfacing,
they see trash in the water.
But they don't realize
the horror of the event
until bodies start floating by.
Estimates say
the Indonesian earthquake
had the energy of 23,000
Hiroshima-type atomic bombs.
[explosion]
The surging waves killed
230,000 people
and left millions homeless
in 11 countries.
It was the single most deadly
tsunami in Earth's history.
No tsunami easily gives up
its violent secrets,
and mankind has not long known
just how bizarre
this kind of wave can be,
producing floods from the sea
so massive,
they seem like
they'll never end.
Tsunamis have struck
in every ocean on Earth,
but 80% of them occur
in the Pacific Ring of Fire.
April First, 1946.
A magnitude-7.1 quake
off Alaska's Aleutian Islands
sends a tsunami 2,200 miles
to Hilo, Hawaii.
It kills 159 people
in waves reaching 50 feet high.
And yet, on the open water,
they are invisible
to the naked eye.
Just a few feet high,
the waves are elongated
over distances so vast,
they seem almost flat.
Tsunami waves we now realize
are totally different
from ordinary waves.
It could stretch for hundreds
of miles in length.
[narrator] The length
of the wave is considered
its distance
from front to back,
rather than its span
along the wave front.
A very long tsunami carries
a huge amount of energy,
enough to propel it
at enormous speeds.
[Kaku] It can travel
at 600 miles per hour.
That's the speed
of a jet airplane.
[narrator] The secret behind
its speed is simple.
In the deep ocean,
there's very little
to get in its way.
[Goldfinger] At the top surface,
you have wind resistance,
which is very low,
and at the bottom surface,
you have the--the seabed,
and the resistance from that
is very low.
There's really nothing
very much to resist it.
[narrator] With that much power,
how would Seattle fare
if a tsunami were to
rip through Elliott Bay?
Minutes after
an offshore earthquake,
the towering wave approaches
the Emerald City's waterfront.
Friction from the suddenly
shallow ocean bottom
acts like a sudden brake,
drastically slowing
the advancing wave.
Waves grow to 16 feet in height
and overtake the city streets.
But the human experience
with ordinary waves
makes it difficult
to understand why tsunamis
are so different.
[Kaku] We realize now that
you have to change
all our prejudices about
what an ocean wave looks like
when you talk about a tsunami.
[narrator] Ordinary waves
are mostly driven by the wind.
Wind waves in the open ocean
are a few hundred yards long.
The secret of tsunamis,
which are predominantly caused
by underwater earthquakes,
is their great length.
Hundreds of miles long,
carrying far more energy
than wind waves.
And tsunamis, even though
they're shortened
from their original wavelength
when they reach shore,
are still far longer than
any ordinary wave.
The secret of their power is in
acting more like massive,
unending currents
than crashing breakers.
For centuries
mankind felt helpless
against the tsunami threat.
But in recent years,
scientists and engineers
have built up their labs,
expanded their research,
and intensified their efforts.
Unable to prevent tsunamis,
they insist people on Earth
can confront them
and learn the secrets
of surviving.
Big tsunamis produce a chaos
of damage wherever they strike.
March 27, 1964,
Good Friday.
The quiet port town of
Crescent City, California,
is struck by tsunami waves
20 feet high.
Ten people are killed,
and 60 city blocks
are under water.
The tsunami is caused by
a 9.2-magnitude earthquake
in Alaska's
Prince William Sound,
the most powerful earthquake
ever recorded in North America.
One hundred nineteen people
are lost in Alaska,
and the local coastal
communities are wiped out.
After such catastrophes occur,
emergency crews are
followed by engineers,
anxious to unlock the secrets
in making mankind's structures
strong enough to survive.
In Onagawa, Japan,
the 2011 tsunami
attacked concrete foundations,
toppling whole buildings.
What you see here
is a classic example
of how we used to
design buildings.
Once the water goes underneath,
it lifts up the building,
almost floats it,
and as the bigger wave
comes in, schook, off it goes.
The whole building topples over.
And my guess is that
this example is going to make it
in all the engineering books
of the next decade.
[narrator] The second wave
that overturned this building
reveals a secret
about tsunamis.
The waves come in a series
known as wave trains,
and the largest wave may come
hours later than the first one.
And the jet speeds
that these waves travel
propel tsunamis thousands
of miles from their source.
[Kaku] One tsunami can ricochet
across the entire Pacific Ocean
in a matter of a day.
In fact, for a tsunami,
the Pacific Ocean is a puddle.
[narrator] The Tohoku tsunami
reached Santa Cruz, California,
5,000 miles away in nine hours.
The ocean height rose
only a few feet,
but water funneled
into a harbor
where boats are supposed
to be sheltered.
Oh, my gosh!
[narrator] The current
heavily damaged every dock
and hundreds of boats.
Oh, man,
that isn't real!
[narrator] Damage to
the California coast
totaled $100 million.
I've never seen
anything like that
in my life.
[narrator] Mankind
is researching waves
to protect itself
from such destruction.
The equipment to do just that
is inside the Hinsdale Wave Lab
at Oregon State University.
A massive 342-foot-long
concrete tank
holding up to 300,000 gallons
of water
is here to create
man-made tsunamis.
To understand ways of
tsunami-proofing buildings,
simple wooden models
are calibrated
to simulate structures
in real-world tsunamis.
But they prove no match
for a worst-case scenario.
This wave represents a tsunami
that struck 6,000 years ago
on the Oregon coast.
With shoreline wave heights
of 48 feet
along 700 miles of coastline,
it may have been stronger than
any modern tsunami.
In a disaster like this,
today's structures
don't stand a chance.
Ohh!
[narrator] There may be no way
to build structures to survive
this level of force.
But deeper foundations
would likely prevent
the toppling of buildings
as revealed in Japan.
And in areas where a tsunami
has wiped the landscape clean,
the secret of survival may be
in not rebuilding at all.
[Synolakis] It's best that we
leave it flat
the way that it is
so that people are not caught
in what is really
a tsunami trap.
[narrator] While earthquakes
cause most of
the planet's tsunamis,
the oceans also face trauma
from other events,
some from the Earth itself,
and others from space.
Earth is a planet with
a wrinkled, buckling crust.
Earthquakes on the seafloor
are known to send sudden pulses
through the oceans,
launching violent tsunamis
against the coasts.
[man] Earthquakes make about 90%
of all the tsunamis,
but there are other more exotic
sources that also make tsunamis
that you might not know about
so much.
[narrator] July 9, 1958.
A landslide
in Alaska's Lituya Bay
causes a tsunami wave higher
than any other
in modern history.
An 8.3-magnitude earthquake
jolted the steep mountains,
shaking loose
91 million tons of rock
which suddenly fell
into the bay.
The resulting waves were
more than 1,700 feet tall.
In 1883, the Indonesian volcano
Krakatoa exploded,
generating a historic tsunami.
What was once a huge mountain
suddenly collapsed into the sea
between the Indonesian islands
of Sumatra and Java.
The sound was heard as far as
3,000 miles away.
Thirty six thousand people
were killed,
most of them from
the surging waves.
And rarely, a comet or asteroid
from space strikes the ocean,
like the one that presumably
killed the dinosaurs
and made Mexico's underwater
Chicxulub crater.
[Ward] When this wave hit,
it made a wave that went
all the way into Oklahoma.
Some people think the wave went
all the way to Canada.
[narrator] Scientists
in the 21st century
have equipped the planet
with a network of ocean buoys
linked to satellites
for detecting distant tsunamis
and giving hours of warning.
But when massive quakes
send the giant waves
against nearby shores,
warnings rarely come
soon enough to help.
When will the next tsunami
crash into our shorelines,
taking lives,
and causing massive
destruction?
It's been suggested that
civilization on Earth
may gain the ability
to control phenomena
like these giant waves
in a few hundred
or thousands of years.
Until it does,
the tsunami will persist
as one of the most powerful
and terrifying
secrets of the Earth.