♪♪
(singing in Italian)
(narrator) Every day, thousands of tourists crowd the streets
of Naples, basking in the romance and history
of this centuries-old Italian city.
But just down the road lies a sleeping monster.
At nearly 4,200ft,
the volcano Vesuvius dominates the landscape.
It has erupted at least 100 times
in the past 10,000 years.
(man) The whole area, the whole Bay of Naples,
is very volcanically active
and it will remain so for a long time.
The oldest rocks in the area immediately
around Vesuvius are 300,000 years old.
And there's been a continuous sequence
of volcanoes and activity since that time.
(narrator) 2,000 years ago, Vesuvius destroyed a city
whose name has become synonymous with disaster--
Pompeii.
And experts believe that another catastrophic eruption
could strike at any moment,
leveling Naples and its suburbs,
possibly killing as many as three million people.
Vesuvius is part of the Campanian volcanic arc,
which includes other famous Italian volcanoes
such as Stromboli and Etna.
(volcano rumbling)
They were formed as a result of Earth's constant
tectonic activity.
Vesuvius began life inside another volcano called Somma.
But Somma collapsed 18,000 years ago,
making Vesuvius the dominant structure.
Together, they're known as the Somma-Vesuvius complex.
- The end result is that this makes this volcano terrain
really quite complex to study,
because you've got the older events
that are in a vicinity of the newer events.
(explosion)
(narrator) In predicting what may be brewing
beneath the surface of Vesuvius,
scientists have an important ally--
history.
The firsthand accounts of activity at Vesuvius
are some of the planet's oldest and most extensive.
In fact, volcanology,
the study of volcanoes,
began with the description of the eruption in 79 AD
by the Roman statesman and philosopher
Pliny the Younger.
The eruption was foreshadowed by a series of earthquakes
that hit the area in June,
and through the next few months.
And then on August 24,
the mountain suddenly came to life.
(explosion)
(Dr. Scatena) By midday on the 24th,
the volcano had ejected this large column of debris
that went up almost 20 kilometers
into the atmosphere, spread out and started to rain
volcanic ash and material
mostly of the size of up to about a centimeter in diameter.
- This episode lasted for about 8 hours
and the deposit was about 10 feet thick.
♪♪
(narrator) The ash column shooting up from Mount Vesuvius
gradually increased in weight until the atmosphere around
the volcano could no longer support it.
The plume cloud collapsed suddenly,
triggering several deadly avalanches called
pyroclastic surges.
Lethal clouds of ash and gas that
instead of shooting upwards,
spread off to the flanks of the volcano.
- These pyroclastic surges and flows are extremely deadly
and there are very few survivors from these effects.
Probably the fraction of survivors
is less than one in a thousand.
(narrator) This flood of searing hot ash, toxic gas and rock
raced down the mountain at 150 miles per hour.
With temperatures more than 1,000 degrees Fahrenheit,
it incinerated everything and everyone in its path instantly.
- When the pyroclastic cloud came,
they basically had no way to escape.
The death is immediate
because you get vaporized.
- The skulls exploded
through the expansion of the brain
and conversion of your body fluids to steam.
So it would be a very rapid,
perhaps a few tens of seconds or 30 seconds,
maybe a minute of actual suffering.
Each subsequent outbreak since 79 AD has had
its own unique characteristics.
An eruption in the third century created a blast that
could easily be heard 25 miles away.
(explosion)
Eruptions in 472 and 512
turned day to night
and spread dust over many parts of Europe.
And three separate explosions
at the end of the 10th century spewed out heavy lava flow.
A volcano that is similar in characteristics to Vesuvius
is Mount Pinatubo in the Philippines.
♪♪
- Pinatubo erupted in 1991,
and around that volcano
there were about 50,00 people in a large American base.
(narrator) The eruption was preceded by
a series of earthquakes in early April 1991.
Scientists from the United States Geological Survey
immediately began onsite monitoring of Pinatubo.
A six-mile radius danger zone was declared around the volcano.
When monitoring instruments indicated that a large eruption
was imminent, troops from Clark Air Force Base
helped spread the word to the local population.
The airmen also coordinated
bus and helicopter evacuation operations.
during a three-week period.
All 50,000 residents were safely transported to shelters.
Then, on the morning of June 15, 1991,
Mount Pinatubo exploded violently
in the largest volcanic eruption
in more than three quarters of a century.
The most powerful phase of this cataclysmic eruption
lasted more than ten hours,
creating an enormous cloud of volcanic ash
that rose more than 116,000 feet high.
Thousands of square miles were blanketed by thick, grey soot,
but the worst of it were the pyroclastic flows.
Hot, toxic gas roared down the slopes of the volcano,
and filled deep valleys with deposits
as much as 600 feet thick.
But despite the devastation, there were few casualties.
(man) The eruption of Pinatubo in the Philippines
was a very drastic, very large eruption
with similar sorts of phenomena
that we might expect at Vesuvius.
The difference is that at Pinatubo,
it was located in a low population region,
but for Vesuvius, it's highly populated,
and therefore, the tragedy associated
with even a much smaller eruption
of Pinatubo's type at Vesuvius would be incredible.
- The Vesuvius, we have a much worse situation
because we have at least ten times more people.
And the area is surrounded by another two million people.
(narrator) Earthquakes, collapsing buildings,
people drowning in ash, deadly gas clouds.
In a worst case scenario, Vesuvius comes to life
and threatens to kill an entire population
within a matter of minutes.
♪♪