Ring of Fire

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Our earth was born of fire.

For two billion years.

volcanoes spewed forth

the magma which the waking

earth would use to build

itself into being.

Volcanoes also vented the gases

which would form

the Earth's atmosphere

and the oceans.

Where life itself was born.

Then in the last seconds

of geologic time

a life form emerged

that would seek to

understand creation itself.

Today, more than 400 active volcanoes

shape life on the pacific rim.

Geologists call it "The Ring of Fire."

From Navidad in Chile and the

volcanoes of the Andes...

to the ancient ash-covered empires

of Mesoamerica...

past San Francisco on

the San Andreas fault.

To Mount St. Helens and the

cascades of America's Northwest...

To the great volcanic island arcs

of the Aleutians.

Siberia...

and Japan.

With sacred Mount Fuji...

and explosive Mount Sakurajima...

to Indonesia, home of Krakatoa...

Bromo...

and Gunung Agung.

Here where half a billion people

dwell is a window on the awesome

geological forces that

shape our planet.

At the very center of the ring of fire,

on the island of Hawaii

exists a lake of molten lava.

In this fiery lake can be seen a likeness

of the Earth's crust

and the geologic forces that shape it.

The Earth's thin crust is formed

of great tectonic plates

which are in constant motion.

Spreading. Colliding.

Grinding past one another.

And plunging back into

the molten interior.

Around the ring of fire,

collisions of the Earth's

tectonic plates produce earthquakes.

And the most violent natural

phenomenon on earth.

This is Navidad volcano

in southern Chile

which burst from the Earth

on christmas day 1988

and grew to a height

of 1,000 feet in a month.

Few people died in this sparsely

populated region.

Yet the immense geological

forces on the ring of fire

can just as easily strike at

the heart of civilization.

7,000 miles north on the ring of fire.

two tectonic plates

meet at a great fault

called the San Andreas,

which lies like a time bomb

beneath the city of San Francisco.

In 1906, a massive earthquake

destroyed this city.

and in the years that followed

San Francisco waited as the stresses

again built up along the fault.

Until one october day in 1989.

The third game of the world series

was about to begin

between the two bay area teams.

The San Francisco Giants

and the Oakland A's.

We're having an earthquake. We're

having an earthquake hold on.

One of the bridges collapsed.

Serious damage on the Bay Bridge.

Part of the upper deck collapsing.

I've never seen anything like this.

There's a major fire burning in

the marina district.

It started at the northeast corner

of Beach and Divisidero streets.

A building there collapsed and

burst into flames.

That is completely collapsed.

That's the upper section collapsing

into the lower section of the cypress.

A truck is upside down. We need

something to pry the door open.

We need something

to pry the door open.

The earthquake lasted

less than 15 seconds

but 62 people were dead and

nearly 4,000 injured.

42 died in the collapse

of the nimitz freeway.

More than 20,000 homes and buildings

were damaged or destroyed

during the quake.

Yet it struck with 1/30th of the energy

of the great quake of 1906.

Engineers learned a great deal

from what structures

survived the quake and what failed.

A 50-foot section of the

bay bridge collapsed

where the forces generated

by the earthquake

sheared the bolts on

one side of the span.

The bridge was repaired and

reopened in the month.

Built on landfill dwellings in

the marina district broke apart...

the unstable ground beneath them

actually magnifying the

effects of the quake.

Buildings engineered to withstand the

greatest earthquakes stood strong.

And so did the people.

Everybody helped each other.

It was like one big family out there.

It knocked us down,

but it didn't knock us out.

There are disasters everywhere.

Everyone lives under

some kind of threat.

If it's not an earthquake,

it's a tornado or hurricane.

It's a beautiful city, regardless.

i love it here. i'll never leave.

10 days after this quake.

we went back to baseball.

Now. That's...

that's the spirit of San Francisco.

Though the flags flew at half-mast.

The fans reunited at candlestick park

to resume a world series

and a game turned into

a celebration of renewal.

600 miles north of San Francisco

is the site of the greatest

volcanic eruption in

modern american history.

Mount St. Helens.

Near where he stood that

sunday morning in 1980.

Photographer Gary Rosenquist

recalls the moment.

At dawn I noticed through some trees

steam at the very top of the mountain.

I got my camera and I just started

taking pictures, and the whole side

of the mountain was sliding away.

I was so excited.

I couldn't concentrate.

It was just amazing. I'd never

seen anything like that before.

240 square miles of woodland

were devastated in the eruption.

57 people and millions

of animals were killed.

Today. A ghostly forest still floats

on the surface of spirit lake.

Across the landscape

of fallen timber

life is reappearing at a rate

that has a astonished biologists.

Deep within the crater, a lava dome

formed in st. helens' volcanic throat

has risen over a thousand feet.

The mountain is rebuilding itself.

With his fellow geologists

from the Cascades

Volcano Observatory

dr. Norman Banks

is credited with saving

thousands of lives.

Our monitoring data

convinced the governor

who was also a scientist,

that an eruption possibly

of significant magnitude

was developing.

Since the explosive eruptions of 1980

we have had to work very

close to the center of activity.

That is the dome itself

to detect the changes

that allow us to forecast

the next eruption.

You can't predict future

eruptions of a volcano

until you know its character.

Some of the instrumentation we use

can be as simple as our own senses.

But to provide data that's quantifiable

we have to resort to high-tech

equipment such as seismometers

deformation equipment,

and gas analysis.

What we're after here

is to obtain the ability

to save thousands of lives

repeatedly around the ring of fire.

Several weeks after the team

left the mountain

the lava dome exploded

without warning.

Volcanologists foresee even greater

eruptions in the future.

For the forces which

created and destroyed

Mount St. Helens contines

powerful beyond our imaginings.

Deep within the earth above a core

of iron and nickel

is a mantle of lighter elements

heated by natural radioactivity.

Over millions of years

the mantle behaves like a heated fluid.

The thin plates of the earth's crust

float like huge rafts adrift

on the fluid mantle.

The heavier plates of the

spreading sea floor

sink beneath the continental plates

creating earthquakes

around the pacific rim.

The sinking plates release

superhot fluids

which melt the mantle above them.

The lighter magma rises

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