NARRATOR:
Deep below the Pacific Ocean lies a tectonic monster. MAN: You know how we told you
not to panic? Well, that's all off. Panic. Run for your life. (screaming) NARRATOR: The world's biggest
tsunami machine, its dangers hidden from view, until now. Imagine if we could
empty the oceans, letting the water drain away to reveal the secrets
of the seafloor. Now, we can, using the latest underwater
scanning technology, piercing the deep oceans, and turning accurate data
into 3D images. This time, is the world's
next mega-earthquake brewing
off the coast of Seattle? MAN: We can have the big one right now, as we speak. NARRATOR:
Why has the discovery of an underwater volcano,
just 44 miles from Tokyo, got seismic experts so worried? And what do scientists caught
up in a undersea earthquake learn about the dangers
facing New Zealand? MAN: The front of it would have
a huge amount of energy. The scale is just immense. NARRATOR: Drain the Oceans reveals the secrets
of the deadly Pacific. (music) (music) The Pacific Ocean-- the planet's largest
and deepest. 500 million people
live around its coast. But deep beneath the waves
lurks a terrifying monster that threatens all of them, the planet's largest and
most dangerous seismic zone-- the Ring of Fire. 90 percent of all earthquakes
strike here and when they do, the consequences
are devastating. (siren) (siren) March 11, 2011. (speaking Japanese) NARRATOR:
Tohoku, northeastern Japan. (shouting) A magnitude 9 earthquake
violently shakes the region. MAN: Oh! NARRATOR: The quake causes
buildings to collapse and people to flee
for their lives. (shouting) But that's not the end
of the destruction. A defining characteristic
of the Ring of Fire is that
the biggest earthquakes here shake not just the land,
but the seabed as well... ...generating
huge surges of water... (speaking Japanese) NARRATOR: ...deadly tsunamis. (shouting) (music) (music) (shouting) (shouting) (music) (music) In Japan, almost 16,000 people
are killed. And geologists are certain
it will happen again somewhere around
the Pacific Ring of Fire, but when and where? Pulling the plug
on the Pacific Ocean reveals a glimpse of one
of its most terrifying secrets, just off the west coast
of America-- not the infamous
San Andreas Fault in California, but something close
to the teeming cities of Portland,
Seattle, and Vancouver, something far more menacing. (music) LELAND O'DRISCOLL: It's known
that it's an active structure. It could happen now, and that's truly the source of fear. (music) NARRATOR:
This region of North America is known as Cascadia, one of the most beautiful
and peaceful in North America. It's also home
to 10 million people. They feel safe here,
and why wouldn't they? In all recorded history,
there's been no trace of any natural disasters
in the region, but on the 18th of May 1980, everything changes. (rumbling) MAN: There is no question at all that the volcanic activity
has begun. NARRATOR: Mount St. Helens,
50 miles from Portland. Huge eruptions blast
a 1,300-foot crater in the summit of a volcano
long thought to be dormant. REPORTER: It is the biggest
eruption ever recorded of Mount St. Helens so far. REPORTER:
I think it does not look good for people in that area now. NARRATOR: It's the worst
volcano disaster in U.S. history,
claiming 57 lives. (music) (music) Scientists are now forced
to ask a tough question. MAN: Is it, is it scaled
to look at tsunamis? NARRATOR: Does the eruption of the supposedly inactive
Mount St. Helens mean the 10 million inhabitants
of Cascadia are now sitting
on a seismic time bomb that just started ticking? To find out, scientists
launch an urgent investigation on land
and deep under the sea. Off the coast of Cascadia,
the latest scanning technology reveals something extraordinary
and terrifying. Based upon their exact data,
for the first time, we can pull the plug
on the Pacific Ocean to reveal
their shocking discovery. As the water drains away, a vast world no human has
ever seen before is laid bare. For mile after mile
across its heart, the Pacific Ocean floor is a vast, flat,
featureless plain... ...until suddenly, the landscape changes. Here, just 150 miles from the great cities
of the Pacific Northwest, a dramatic transformation
takes place, revealing a fractured,
broken seafloor... ...brooding, menacing. O'DRISCOLL: One of the best
analogies I can think of is looking
at the, the front end of a car that's been
in a head-on collision, dented and corroded
and corrugated into this complex mess. NARRATOR: The scale of
this geological fender bender is truly epic. Colossal cliffs, almost twice the height
of the Grand Canyon... ...some deep enough to hide
six Empire State Buildings stacked on top of each other, all of it stretching 700 miles
along the Cascadian coastline. This titanic rupture
in the earth's crust is what geologists call
a subduction zone. At the core of our planet is a boiling cauldron
of molten iron, surrounded
by a thick mantle of rock. That outer crust is divided
into huge tectonic plates that are constantly
in motion. When they collide,
they thrust mountains upwards and carve deep trenches
into the ocean floor as one plate drives the other
back inside the earth. If the plates lock together, tremendous pressure
begins to build. O'DRISCOLL:
Only in subduction zones where the plates
are compressing together and there's this lock
between the plates, that, those are
the only fault zones that have the potential to create magnitude 9.0 and higher events. NARRATOR: But that's not all. Subduction zones,
because they are underwater, can generate not just
earthquakes, but huge tsunamis. Written history suggests
that Cascadia's subduction zone has been inactive
for centuries, but does written history
go back far enough? Is this monster really
as sleepy as it seems? (music) Scientists scour
the landscape around Cascadia in search of answers, and, in the banks
of coastal rivers like this, they find an alarming pattern. DAVID YAMAGUCHI: It's very much
like a chocolate cake. You slice a chocolate cake, and there's a layer
of brown frosting, and then, down below, there's
another layer of brown frosting, and the Washington coast
looks very much like that. NARRATOR:
But there's nothing sweet about these layers
of peat and sand. YAMAGUCHI:
Each of these buried soil layers on the Washington coast reflected times when the coast
had been jerked downwards by the occurrence
of an earthquake. NARRATOR:
In the layers of peat, David Yamaguchi
and geologist Brian Atwater unearth evidence
of seismic devastation stretching back
over thousands of years, quakes that scarred the entire
coastline of Cascadia. The question now is, when was the last one,
and how big was it? NARRATOR: The Copalis River,
Washington State. Scientist David Yamaguchi
is on a quest. He and his fellow scientists
already suspect that the 10 million inhabitants
of Cascadia are living
on a seismic time bomb, but when did it last go off, and how big was it
when it did? Three miles inland, he comes
across a haunting sight. (music) (music) This is what's left
of a once mighty forest of red cedar
and spruce trees, thousands of petrified corpses scattered
over hundreds of miles along Cascadia's coast. YAMAGUCHI: And the mystery here is what killed the trees, and when did they die? (chainsaw) NARRATOR:
Sampling dozens of the trees, Yamaguchi analyzes
their age rings, and what he finds
is a new mystery. YAMAGUCHI: The trees were fine
and healthy in 1699. Then, the following summer, the trees that, that would
normally have produced another annual ring were nearly all dead. NARRATOR: What happened
to kill an entire forest in one instant? Another scientist
thinks the answer could lie deep in the geological
car crash of the Cascadia
subduction zone, just 100 miles away. (music) Chris Goldfinger is an
underwater earthquake detective seeking evidence
in core samples taken from deep
under the seafloor. Studying the layers of sediment reveals when and where
earthquakes struck in the past and how powerful they were. CHRIS GOLDFINGER: Sediment
settles to the seafloor, but it got there somehow, from some storm, an earthquake,
and even a volcanic eruption will leave a deposit
on the seafloor, and so it's just
a very precise, three-dimensional
tape recorder, just recording
every single thing that happens. Well, this is a core sample from, from the seafloor
off of Cascadia, and it's about
2,000 years' worth of sediment. NARRATOR:
In the middle of the sample, dating to roughly
300 years ago, Goldfinger finds the classic
signs of a large earthquake. GOLDFINGER: Well, in fact,
the shells like this turn out to be
shallow-water fossils, but this is a deep-water core, so these things
were carried down from shallow water
to deep water. What this points to is
a fairly dramatic kind of event. (rumbling) NARRATOR: That dramatic event
was an earthquake that triggered
a vast underwater landslide. And it all happened
around the same time that Yamaguchi's trees died. Next, he compares core samples
of the same date, taken along the 700 miles of the Cascadia
subduction zone. Core after core reveals
the same disturbed layer, all occurring
at the exact same time. This is evidence
of no ordinary earthquake, but a monster. GOLDFINGER: Cascadia, through
the study of past earthquakes, has shown that it's capable
of generating earthquakes that run the full length,
roughly 1,000 kilometers. NARRATOR: In 1700,
the Cascadia subduction zone generated a cataclysmic quake
along its entire length, with a magnitude that
Goldfinger and other scientists calculate as level 8. But that's not all. This was more
than just an earthquake. Japan has a long history
of earthquakes and tsunamis, with written evidence
going back 1,400 years. Among these historical records, in accounts written
by samurai and merchants, researchers uncover reports
of a 16-foot tsunami that arrives
from far out in the Pacific, swamping the eastern coast. It destroys houses and causes villagers
to flee to higher ground. The date of these reports? 1700. YAMAGUCHI: They propose that
our earthquake was magnitude 9. A magnitude 8
was not big enough to produce a wave
that's that wide. In addition, based on the arrival times
of the waves in Japan, the earthquake
must have happened here on January 26, 1700 at 9:00 at night, yes, local time. NARRATOR: The Cascadia
mega-quake was so powerful that it generated a tsunami that hit Japan,
4,500 miles away. Using the combined insights of experts from both sides
of the Pacific and the extraordinary
drained landscape of the subduction zone, it's now possible to visualize the titanic events
of January 1700 and its deadly trail
of destruction. (music) GOLDFINGER:
The entire subduction zone shakes very hard. The ground motion is big,
and it's over a big area, so it's gonna shake
a lot of sediment loose. (music) There are gonna be
hundreds of landslides. They're gonna all
come tumbling down the slope and leave a deposit. (music) (music) NARRATOR: The quake
also triggers a huge tsunami which smashes
into the coast of Cascadia, flooding the land
with seawater, including the red cedar forest and everything else
in its path. Although
there is no written history of the 1700 earthquake
and tsunami in Cascadia, native peoples of this region do hold haunting memories
of these terrible events. GOLDFINGER: The First Nation
peoples had oral histories about the great battle
of Thunderbird and Whale that had a lot of shaking
of the ground, washing away of villages. MAN: The Great Thunderbird finally carried the Whale
to its nest. There were a shaking,
jumping up, and trembling
of the earth beneath and the rolling up
of the great waters. GOLDFINGER: So, once
these stories came to light, the Native Americans
essentially said, 'Why didn't you just ask us?
We knew all about that.' The story had a moral,
and the moral was, don't build your village
too close to the beach. NARRATOR: But evidently,
no one was listening. Today, 10 million people live
along the coast of Cascadia and in the cities of Seattle,
Portland, and Vancouver, and the question is
how likely is it that the monster
will roar again? THOMAS HEATON: It's not at all
like a clock, but the average time between the earthquakes is on the order of 400 years. NARRATOR:
If the Cascadia subduction zone repeats its 400-year cycle, then its next mega-quake
could be imminent. O'DRISCOLL:
We know the strain is building, and we know, one day,
it's gonna be released, and that could happen any day. NARRATOR: So, what will happen
when the monster wakes? GOLDFINGER:
In a subduction zone earthquake, energy is stretched out,
not 10 seconds or 20 seconds, more like three minutes. HEATON: The shaking's not incredibly violent, but it lasts for a long time, and it's a very long, rolling motion. For tall buildings,
that's not good news. NARRATOR:
With buildings collapsing and infrastructures shattered, it will be hard
for the population to escape from the coastal area, the worst place to be trapped. HEATON: You know that
if you get a giant earthquake, you'd better assume you're about to get a giant tsunami. NARRATOR: The tectonic plates'
sudden release of pressure forces a massive swell
in the ocean above. GOLDFINGER:
So, the wave height, initially, might only be
a couple of meters, but it might be
200 kilometers long, and it heads out
at the deep-water wave speed, which is very fast,
so it's jetliner speed, 500 or 600 miles an hour. Everything we've seen in Japan,
we can expect, basically, the exact same thing
in Cascadia. (man on loudspeaker) HEATON:
30 meters of water rushing in at 10 meters a second
kind of velocities... ...it just scours everything off the, off the surface of the earth. NARRATOR: Within 20 minutes, the tsunami will approach
the coast of Cascadia. GOLDFINGER: When that wave
starts feeling bottom, like all other waves do, it gets compressed
from 200 kilometers down to a kilometer or two. HEATON: It's like an enormous tide happening very quickly. (music) NARRATOR: A Cascadia mega-quake
is predicted to be North America's
worst ever natural disaster. O'DRISCOLL: The fatalities
could be fairly large. We're looking at, at a few tens
of thousands of people, at least, on our coastline. We know the strain is building, and that's quite harrowing
to know that we could have the big one
right now, as we speak. NARRATOR: But Cascadia is not
the only populated region in the Ring of Fire
danger zone. As the waters of the Pacific
continue to drain away, they reveal
another sleeping giant near the east coast
of New Zealand, where scientists discover
traces of an epic seismic event that reshaped
the Southern Hemisphere and ask,
when will it happen again? NARRATOR:
The islands of New Zealand lie directly
on the Ring of Fire. Small earthquakes shake
the ground here every week. (sirens) (screaming) In 2011, the country's second
largest city, Christchurch, is devastated
by a magnitude 6.3 quake... WOMAN: I can confirm
that there have been deaths. NARRATOR:
...killing 185 people. (siren) 100 miles from Christchurch is the town of Kaikoura. MAN: Kaikoura, welcome aboard. WOMAN: Thank you. NARRATOR:
A peaceful holiday resort that's popular
with nature lovers. MAN: Keep looking out there. You'll see them just
out of the front of us there. NARRATOR:
Its deep, nutrient-rich waters entice whales
close to the shore. MAN: This is
the beautiful humpback, and it is awesome to see humps. NARRATOR:
While these leviathans are Kaikoura's
star attraction, geologists now come here
for a very different reason. New Zealand's geologists
constantly monitor the threat posed
by the faults and fissures that run under the islands, trying to discover where the
next big quake might strike. Ground surveys can help, but investigating
under the waves has always been a challenge, until now, because the latest
multiple-beam sonar technology is opening up a hidden world. JOSHU MOUNTJOY: It's multiple
beams of sound energy being released from
the instrument on the vessel, and we time how long it takes
for that beam to come back. (beeping) We do what we call
mowing the grass, and we're just collecting
this continuous image of what the shape
of the seabed is. NARRATOR: And the shape
of the seabed near Kaikoura is not what they expected. As the data comes in,
it slowly reveals something astonishing
and potentially lethal. Pulling the plug
on the Pacific Ocean exposes the remarkable sight. Just a half mile
from the town of Kaikoura, as the water drains away, it reveals the plunging walls
of a vast, undersea chasm... ...the Kaikoura Canyon. MOUNTJOY: The Kaikoura Canyon, it comes within
a really short distance of the coastline out here,
less than a kilometer, and, from there,
it drops down at 30, 40 degrees down to about 600 meters
water depth. Then it carries on down to
about 2,000 meters water depth. NARRATOR:
Stretching for over 37 miles, the canyon forms part of one of the deepest
sea channels in the world. The walls nose-dive
over 6,000 feet-- the depth of the Grand Canyon. Geologists wonder at
the immense geological forces involved to create
such a huge canyon... ...but also ask themselves, does it pose a threat to those
living on the nearby coast? Geologists know that landslides triggered by earthquakes
in underwater canyons can generate lethal tsunamis. Could the Kaikoura Canyon
do the same? On board the research ship
Tangaroa, they investigate. MAN: Let's try it again, Mitch. (radio chatter) NARRATOR: Using Perspex tubes,
they gather evidence from the sedimentary layers
on the canyon's floor, looking for signs of seismic
activity in the past. MAN: Yep. MAN: This is core two. NARRATOR: But then, just
as they're studying history, they get the chance
to make some. Midnight, November 14, 2016. (static) WOMAN: And we are undergoing
a fairly dense earthquake at the moment, so, please,
just get to somewhere where you are safely
under some protection. I can honestly say,
I doubt that I'll be able to stay in the chair
for much longer. (alarm) NARRATOR: The 7.8 magnitude
quake rips apart the earth, creating giant crevices and
billions of dollars of damage. Geologist Joshu Mountjoy has
never seen anything like it. MOUNTJOY: The key thing was
that it just covered such a large geographic area, and it was right
on our coastline. NARRATOR: The quake rattles
the ground for two minutes, causing thousands
of landslides across 3,800 square miles. Just north of Kaikoura
is the biggest. 800 million cubic feet
has shaken to the ground, exposing a virgin cliff face
almost a mile wide. MOUNTJOY: Grass and tussock
we're standing on was connected to
that grass and tussock up there, and then the whole block
slid right down to bring it down
to where it is now, so this has happened
during the earthquake. We call that co-seismic,
and there's actually a fault line
running through here that runs
right down to the coastline. NARRATOR:
The shaking is so severe that it thrusts the foreshore
of Kaikoura upwards by three feet
in just one second. MOUNTJOY: We're looking at here, we can see
a whole a lot of seaweed that's stranded
above the tide line. Before the earthquake, that would have been
down below the sea level. NARRATOR: But Joshu Mountjoy
isn't only interested in how the earthquake
tears apart the land. As soon
as the earthquake begins, he wants to know
the effect it's having deep under the ocean, in the newly scanned
Kaikoura Canyon. Mountjoy makes contact with
the research ship Tangaroa, which is mapping
the very far end of the canyon. MOUNTJOY: We requested
that they divert their energy to focus on doing
some earthquake response. NARRATOR: That response is to
immediately gather core samples from the floor of the canyon
before the dust has settled. ALAN ORPIN:
So, we really had an unprecedented opportunity
to assist. Well, what, what is the
aftermath of a major earthquake? NARRATOR:
If the crew responds in time, they can achieve a world first, recording the impact
of an earthquake in a deep-sea canyon
as it happens. NARRATOR: Within minutes
of the earthquake, the crew retrieves precious
core samples from the seafloor. MOUNTJOY: They collected
the sedimentary deposit that had only just happened,
so they were boring it while it was probably still
settling out of the ocean. NARRATOR: And what marine
geologist Alan Orpin discovers is intriguing. ORPIN: What we found was
a very soupy, fluidized mud that was lying
on the seabed. As we moved south, what we found
was compelling evidence of core after core
for a thickness of material that had spilled down
through the channel. NARRATOR:
The more samples they take, the clearer
the picture becomes. The shaking of the quake
has created a secondary and truly spectacular
undersea upheaval. MOUNTJOY: No one's ever
been able to observe one of these huge landscape
scale canyon-flushing events to show exactly
what effect it had on the canyon itself. (music) NARRATOR: Using the data gathered by the crew
of Tangaroa and the remarkable
drained seascape, the impact
of a large earthquake on a gigantic underwater canyon can now be visualized
for the very first time. The seabed shudders ominously
as huge tectonic forces power through
the earth's crust. (rumbling) This dislodges
a top layer of sediment, becoming a gigantic
canyon-flushing landslide. (rumbling) (music) Rock and sediment
tumble down the steep walls. 850 million tons of debris
roars through the canyon, gouging 160 feet
out of the floor. MOUNTJOY: There's really like
a powder snow avalanche. The front of it would have
a huge amount of energy moving at about
70 kilometers an hour and maybe 400 meters high. It's spreading
tens of kilometers across the ocean floor. It's just gonna take over
everything that's down there. NARRATOR: The landslide travels
with such velocity, it carves a path
across the seafloor for an astonishing 435 miles. A landslide of this ferocity
has the potential to generate a tsunami
that could devastate Kaikoura. MOUNTJOY: When a landslide
creates a tsunami, you need a large chunk
of material to slide downslope, and what happens is it's
coupled to the water above it and actually
pulls it down with it, and then,
as that water rebounds, then you create your wave. NARRATOR:
This time, Kaikoura is lucky. No large objects
fall off the canyon rim. Next time, the town may not
be so fortunate. And the dramatic events of 2016
draw the geologists' attention to an even bigger
tsunami threat nearby. By continuing
to drain the ocean off the northeast coast
of New Zealand, we can see the reason
for their fear. Lurking just north
of the canyon and frighteningly close to the New Zealand capital
of Wellington-- the Hikurangi subduction zone, 2,174 miles
of seismic trouble. Geologists recently learned
that stress has been building at its southern end
for hundreds of years, and they believe
that the 2016 earthquake has ratcheted the pressure
up even further. Understanding
what's happening here has become
an international priority. 100 ocean floor
seismic measuring devices and support scientists
recently arrived from Japan. They're here to monitor and
record the mounting stresses in the hope of discovering
the true danger of Hikurangi. (music) Geologists delve deep into the subduction zone's
tectonic past. And their results
are astounding. It hasn't fractured recently,
but deep in its past, it produced something bigger
than anyone had imagined. Now, using
the geologists' data, it's possible to reconstruct,
for the first time, a tectonic event
that reshaped a hemisphere-- the Ruatoria avalanche. Just 200 miles from
what today is New Zealand's bustling capital, Wellington, the epicenter of one
of the biggest seismic events in the history of the earth. (rumbling) 170,000 years ago,
the Australian plate is bearing down
on its Pacific neighbor, grinding down
everything in its path. Even a towering
volcanic cone six times the volume
of Mount Fuji becomes collateral damage. The resulting seismic shock triggers
an underwater landslide on a scale rarely seen. Moving a swath of broken rock, the equivalent
of three-quarters the size of the Grand Canyon. (rumbling) (rumbling) MOUNTJOY:
So, the Ruatoria avalanche is the second biggest submarine
landslide in the world. It's absolutely enormous,
3,000 cubic kilometers. And if you can try and visualize
a cubic kilometer, that's a kilometer high by a kilometer long
by a kilometer wide, 3,000 of them. (music) NARRATOR: Nobody knows when
the Hikurangi subduction zone will facture again, but when it does, geologists estimate the tsunami
wave from the mega-quake will take only seven minutes to reach New Zealand's
capital city, Wellington, and its
half a million residents. And such a huge tsunami wouldn't only impact
New Zealand. There would be
an ocean-wide alert as the waves fan out
into the Pacific. (screaming) The last time a tsunami
on this scale hit the southern arc
of the Ring of Fire was December 26, 2004, devastating 14 countries and killing 230,000 people-- a terrible reminder of the
power of the deadly Pacific. Continuing to drain away
the Pacific Ocean reveals a very different kind
of seismic threat 5,000 miles away, right next to one of the most
densely populated cities on the planet. Just 44 miles
from bustling Tokyo, a mysterious underwater feature has scientists
on the edge of their seats. The island nation of Japan suffers from its position
on the Ring of Fire. The country accounts
for about 20 percent of the world's earthquakes
of magnitude 6 or greater. Its biggest city, Tokyo, has been hit
by nine mega-earthquakes in the past 95 years. But just 44 miles
off the city's shoreline, geologists
have recently discovered a new and very different
tectonic troublemaker. The first discovery is made
by scientist Ken Tani. He's heading out to test his new underwater remotely
operated vehicle, or ROV, in the waters
just off the island of Oshima, south of Tokyo Bay. Until now, the waters here have
been considered safe passage for one of the busiest
shipping lanes into the port of Tokyo, with 400 vessels
passing through here every day, but that is about to change. NARRATOR:
44 miles from Tokyo Bay, Ken Tani prepares an underwater
survey, using an ROV. (speaking Japanese) Passing over a rocky mound
on the seafloor, he discovers
something extraordinary, a seismic beast
that has lain hidden for hundreds of thousands
of years. Using Ken Tani's own data,
draining away the Pacific Ocean reveals what is lurking
below the waves. As the water recedes, it exposes
a large flat plateau. Near its center, what looks like an ordinary
hole in the seafloor. But on closer inspection,
the frightening truth emerges. It's the vent
of an undersea volcano. Thousands of years ago, it very likely
had a towering cone, but erosion and wave action
has worn it down, which is why
no one discovered it before. But is it as dormant
as it appears? Ken wastes no time
in exploring the crater. KEN TANI:
So, that's the sea surface. NARRATOR: Testing the water
temperature around the outlet with a submarine thermometer, and what he finds
surprises everyone. (music) NARRATOR:
The smoldering undersea volcano is named Oomurodashi, 44 miles south of Tokyo, placing at risk the lives
of thousands of mariners in the shipping lanes above. In 1952, an underwater volcano
like Oomurodashi erupts 260 miles
south of Tokyo. Super-heated magma
reacts with water to produce what's called
a phreatomagmatic explosion, an underwater steam bomb. A nearby ship is engulfed
in the explosion, killing all 31 on board. NARRATOR:
A stirring volcanic giant is not just
a danger to shipping. A major eruption
could send tsunami waves racing towards Tokyo,
population 38 million. NARRATOR: Ken decides he needs to keep Oomurodashi
under surveillance. Nothing happens for five years. Then, when he returns
to gather fresh samples, Oomurodashi has another
unpleasant surprise for him. Returning
to the drained ocean floor reveals his next
shocking discovery. In addition to the crater, five more volcanic cones. That's five more possible
outlets for the volcano. Only one is currently active,
but all could become so. And if the volcano
keeps growing, Oomurodashi could become
an even greater threat by breaking the surface and spewing toxic ash
into the sky. Active volcanos can do this
astonishingly quickly. It took Nishinoshima,
Japan's latest volcanic island, just two years to grow from a flat-topped,
underwater summit to this tectonic monster, measuring one square mile
and 443 feet high. But Nishinoshima is nearly 600 miles from Tokyo. Oomurodashi is only 44. Once out of the water, any major eruption
of Oomurodashi could shower Tokyo
in choking volcanic ash. Despite the dangers,
Ken Tani and his team continue
to monitor Oomurodashi. Any increase
in the volcano's activity could signal
impending disaster for the thousands living
on nearby islands and threaten the safety
of millions in nearby Tokyo. Draining the Ring of Fire has revealed
hidden geological wonders and terrors, exposing new evidence
of this immense power of plate tectonics and its ability to create and destroy.
