All language subtitles for Secrets Series 6 Part 4 Romes Sunken City 1080p

Narrator: A massive storm

Reveals a lost
underwater metropolis.

Arya: How about
rediscovering the city?

That's unbelievable.

Narrator: The sunken
city of neapolis,

Once a vital port for the
sprawling roman empire.

Arya: With supply and demand,

Neapolis is just going
to grow and expand.

Narrator: And the
key to its success:

A must-have ingredient

That came to symbolize
roman identity.

Lowe: This is the ketchup
of the roman world.

Narrator: Experts
are piecing together

The untold story of neapolis

And how it became essential
to the roman war machine.

Arya: It's about location,
location, location.

Narrator: Before
a mysterious disaster

Wiped it from history.

Jackson: The ground turns to
fluids and the city disappears.

Lowe: It's devastating.

Narrator: Hidden by the
waves for over 1,500 years,

The ruins of neapolis
are revealing secrets

Of the rise and fall of the
world's greatest empire.

Lowe: Once the roman empire
breaks down, the world shrinks.

(dramatic orchestral music)

Narrator: The relics
of the past hold secrets.

(stones rumbling)

Written in gold,
(hammer clinks)

Stone,
(instrument clinks)

And blood.

We can unlock them.

These are the secrets of
history's greatest treasures.

(dramatic orchestral music)

(tense orchestral music)

Tunisia, north africa.

Today, a popular
tourist destination

By the mediterranean sea.

But 2,000 years ago,

This african country
was a vital dominion

Of the roman empire.

Arya: When we talk about
the roman empire,

Sometimes people are
surprised to learn

That the entire
strip of north africa

Was part of that roman expanse.

Birley: North africa was a
hugely significant part of rome.

It was the main bread winner

For a very, very large
part of the empire.

Narrator: Tunisia
lies hundreds of miles

Across the mediterranean
from the heart of the realm,

But its fertile
lands were crucial

In feeding rome's almighty army.

And as the empire grew,
tunisia flourished,

Its vast new wealth
funding lavish examples

Of roman architecture,

Including a 35,000
-seat amphitheater

Modeled on rome's colosseum.

Arya: This, more than
anything else maybe,

Was saying rome is here.

And when you make it this big,

It's a really massive statement.

(crowd roaring)

Narrator: But 100 miles
north of the amphitheater,

One roman settlement in tunisia

Has perplexed archeologists
for centuries.

On the outskirts of the
coastal town of nabeul

Sit mysterious high
-status roman villas.

Ancient records reveal
this was the location

Of a prominent city
called neapolis.

(dramatic orchestral music)

And it was deemed
so significant,

It may have been declared
an official roman metropolis

By julius ceasar.

But the archeology is an enigma.

The ruins here are
nowhere near big enough

To match the bustling city
history seems to record.

(ocean waves crashing)

So, where is the rest of it?

And why has it vanished?

The answers to these questions
would remain a mystery,

Until now.

Because an incredible
chance discovery

Has revealed one of the
greatest forgotten cities

Of the roman empire.

(gentle orchestral music)

The history and fate of neapolis

Has intrigued archeologists
for hundreds of years

Because ancient documents
reveal next to nothing

On how this once thriving roman
city gained its importance.

Lowe: Like so many cities,
it doesn't feature

In the history of the empire.

The written sources focus
on what's going on in rome,

They don't recount what's
happening in the provinces.

And so neapolis disappears.

Narrator: But the
archeology on land

Reveals an elite social class
at the heart of neapolis

That rivaled even rome's.

(dramatic orchestral music)

Some of the most
striking evidence

Is now kept at
the nabeul museum,

Including a series of elaborate
and expensive mosaics,

All recovered from
just one villa.

Arya: There's so many of these
mosaics in one single house.

The owner had sophisticated
taste, was wealthy,

And was able to commission
great works of art,

In this case in the
form of mosaics,

That rivaled those anywhere
in the roman empire.

Narrator: It seems some
of neapolis's inhabitants

Became very rich
(man laughing)

And took pride in flaunting it.

And for dr. Darius arya,
the most striking example

Is a square mosaic found
in the villa's dining room.

Arya: You've got these
two roosters

Dropping gold coins
into this jar,

And so much so that it's filled
up and it's spilling out.

The owner of the house,
he's saying to his guests,

"look at this, I'm
really successful,

"so much so that the coins are
just spilling out of this jar

"and on to the ground, I'm
more successful than you are."

Narrator: So what
could have been the source

Of such extreme wealth?

And could it unlock the secrets

Of neapolis' seeming importance?

For the past 15 years,
archeologist dr. Mounir fantar

Has attempted to
solve this mystery.

(fantar speaks in
foreign language)

(ocean waves crashing)

Narrator: The few records
of neapolis that do exist

Mention the city had
a commercial port.

But fantar had failed to
find any evidence of it

In the site's archeology.

(fantar speaks in
foreign language)

Narrator: It
took a massive storm

To finally give
fantar his answer.

(thunder booming)

In 2013, heavy winds hit
the southern mediterranean,

Ravaging the seabed off
the coast of nabeul.

(gentle orchestral music)

Days later, strange stone shapes

Began to emerge
from the sea floor,

Shapes that appeared
unnaturally straight.

Further investigations
revealed something startling.

They were remains of
a roman settlement.

Stone blocks, columns,
and foundations.

(fantar speaks in
foreign language)

Narrator: Could these remains

Be the missing harbor
front of neapolis

Fantar had been searching for?

To find out, he and his team

Took their investigation
to the sky.

Using drone imagery, they
built up a full view from above

Of the ruins on
land and underwater,

And it revealed
something astounding.

(drone buzzing)

(mysterious music)

The remains in the sea lined
up with those on the shore.

For fantar, this could
only mean one thing.

(gentle orchestral music)

They must have belonged to
the same roman settlement.

It was a discovery that
stunned archeologists.

Arya: How about rediscovering
half of a city?

So to connect what
we have on the land

With what is under the
sea, that's unbelievable.

(dramatic orchestral music)

Narrator: Now, after years
of underwater investigation,

Fantar's team has mapped out

A complex of buildings, streets,

And a large industrial site.

The remains of neapolis have
grown from a suburban community

To a vast urban layout.

And these newly-discovered
submerged ruins

Could finally unlock the
mystery of neapolis' importance.

Because they seem to include

What fantar had spent
years searching for:

Ruins of a harbor, just as the
historical records suggested,

Large enough to make it a major
hub for international trade.

(fantar speaks in
foreign language)

Narrator: On
land and underwater,

The ruins of neapolis now
bear all the hallmarks

Of a major roman port.

But what was the secret
of the city's success?

And what ultimately
destroyed it?

(water gurgling)

The discovery of sunken
roman streets, buildings,

And a massive harbor
off the coast of tunisia

Has stunned archeologists.

The submerged remains,
together with ruins on land,

Are evidence this was once

The powerful roman
port city of neapolis.

Now experts are trying
to piece together

How neapolis earned
its wealth and power.

They suspect some of
the city's fortunes

Came from the lush
tunisian produce

That fed the roman empire.

Arya: When we think of
north africa today,

We think of dryness, heat.

Back in the day, it
was a lot more humid,

A fertile breadbasket area
that would have supplied grain

And other agricultural products

To rome and the
rest of the empire.

Narrator: Set on the coast,
neapolis was perfectly sited

To export food from
tunisia's interior

To roman ports across
the mediterranean.

Arya: It's about location,
location, location.

With supply and demand,

Neapolis is going to grow
and flourish and expand.

Narrator: But dr.
Mounir fantar believes

Neapolis earned much of
its wealth and status

From something else,

Something everyone wanted
across the roman empire.

And a clue can be found
among the ruins on dry land:

An intricately
decorated ceramic basin.

(fantar speaks in
foreign language)

Narrator: For fantar, this
depiction of the god oceanus

Reveals the coastal
city flourished

Thanks to the bountiful stocks
of fish in the mediterranean.

But there's no evidence that
neapolis made its fortune

By catching and
exporting fresh sea food.

In fact, the archeological site

Reveals only their
rotting remains,

Laid out in a collection
of stone tanks.

(fantar speaks in
foreign language)

Narrator: Fantar
believes these tanks

And the rotting fish inside
were the secret to success

Because they were used to make
a fish sauce called garum.

(gentle music)
(liquid dripping)

Garum became the condiment
of choice across the empire,

Used for cooking and
enjoyed as a garnish.

It was the quintessential
roman ingredient.

Birley: Garum is just a
fundamental part

Of the roman diet.

And anybody who would require
it as part of their food,

It's something they're used to,

It's a flavor which they enjoy.

Lowe: Garum is found
everywhere in every house

Regardless of wealth.

Everybody is eating this.

This is the ketchup
of the roman world.

Narrator: But what made
this fish sauce so special?

The secrets of why romans
consumed so much of it

Have remained elusive

Because it had been thought
the original recipe for garum

Had been lost to time.

But now it's being resurrected,

Thanks to an
incredible discovery

In one of ancient rome's
most fascinating lost cities:

Pompeii.

(dramatic orchestral music)
(volcano booming)

In 79 ad, the eruption
of mount vesuvius

Buried the city under 20 feet
of ash and volcanic rock.

(ash crackling)

But this thick layer also
acted as a preservative,

Slowing down the decay
of organic material.

In 2014, professor
dario bernal-casasola

And his team from the
university of cadiz

Began excavating at pompeii

In search of garum,
frozen in time.

Bernal-casasola: Pompeii has
an extraordinary

State of preservation
of the remains

That normally we can't find
in other archeological sites,

And we wanted to find
organic residues of garum.

(gentle orchestral music)

Narrator: In an
incredible stroke of luck,

The team found a garum store,

And inside were 2,000-year-old
traces of the sauce itself.

Now, for the first time ever,

An actual sample of
garum could be analyzed

To find out exactly
what it was made of.

The team joined forces

With experimental scientist
dr. Victor palacios.

(palacios speaks in
foreign language)

(bernal-casasolas speaks in
foreign language)

Narrator: Through
microscopic analysis,

The team found pollen grains,

Revealing a selection of
herbs were used in pompeii

To flavor the sauce.

(palacios speaks in
foreign language)

Narrator: The team
believes garum was made

With varying combinations
of herbs and fish,

Depending on local tastes.

And the sample told them
exactly which species of fish

Was used in this
pompeiian recipe.

Bernal-casasola: The remains has
allowed us to study the bones

In order to know the species
that they were using.

We know it was being
produced with anchovies.

Narrator: But the team
found one part of the fish

Was key to the whole
concoction: Its intestines.

These have enzymes

That literally digest the
protein in the fish muscle,

Turning it into liquid.

Archeologists have found
ancient garum-making tanks

Across the roman world,

All with a similar
design and engineering

To the tanks
uncovered at neapolis.

Dead fish were left
to ferment with salt

In the higher tanks,
and as they did,

The pipes drained
the resulting liquid

Into the lower reservoir,

Capturing the juice which
would become the final product.

The large quantities of salt
used in the fermenting process

Meant the sauce
would keep for years.

(gentle dramatic music)

The result was a tasty
protein-packed shake

That provided much
needed nutrients

To the mainly cereal
-based roman diet.

Lowe: Imagine you are primarily
eating grain-based porridge.

Garum is probably the
principal source of protein.

Narrator: In the
land-based ruins of neapolis,

Experts counted around
100 garum-making tanks,

Suggesting a substantial
scale of garum production.

But in the underwater remains,

Divers found something
extraordinary.

(diver gurgling)

There were at least
another 100 tanks

Hidden beneath the waves.

It's a discovery that reveals

Why there was such a large
commercial port here.

Neapolis was actually
the epicenter

For the mass production
of fish sauce.

(fantar speaks in
foreign language)

Narrator: For mounir fantar,

It's conclusive evidence
neapolis made its fortune

Through producing
and exporting garum

On a scale unrivaled in
the rest of the empire.

But how did its
producers in neapolis,

On the southern boundary
of the vast roman world,

Manage to reach markets
thousands of miles away?

The answer can be found on the
opposite edge of the empire,

In a unique collection of
documents suggesting neapolis

Was part of the ancient
world's greatest supply chain,

One that would power the
roman military machine

As it conquered over
two-million-square miles.

(dramatic orchestral music)

Off the mediterranean
coast of tunisia,

Archeologists have made
an incredible discovery.

The submerged remains
of an ancient harbor

Confirm this was once home

To a crucial commercial
hub for the roman world.

The city of neapolis.

Here, they produced and exported

Vast quantities of a
fish sauce called garum,

And it became the ultimate
must-have condiment

In an empire that covered
almost two-million-square miles,

From the north african coast

To the furthest
reaches of England,

Almost 2,000 miles
from neapolis.

Birley: So we're at the very
northern part

Of the roman empire,

On the border, the
frontier of the empire.

Narrator: Around the
early 2nd century ad,

The largest roman army
in the entire empire

Was stationed here
on hadrian's wall,

Struggling to keep hold of
its newly occupied territory.

Birley: The british really
didn't wanna be conquered.

So over 30,000 soldiers and
their families and communities

Were stationed permanently
in roman britain.

(tools clinking)

Narrator: For
the past 13 years,

Dr. Andrew birley has
supervised investigations

At vindolanda fort.

Birley: Liz, that's
looking wonderful.

Narrator: One of 16
heavily defended garrisons

That ran the length
of hadrian's wall.

And he's found evidence
it was manned by soldiers

From across the empire.

Birley: You'd get people
from syria,

North africa, Spain,
Italy, France,

Coming to this part of
the world for one effort,

One big military effort.

Narrator: Among
vindolanda's many treasures,

Archeologists have
uncovered around 500 letters

Sent to and from roman
troops based at the fort.

And many contain requests for
favorite foods from back home.

Birley: You've come to a
completely different

Alien environment,

One of the ways that you can
feel comfortable, of course,

Is having that taste from home.

Narrator: The
finds have revealed

That even here on
this faraway frontier

Soldiers were being
sent a variety of goods

From their home countries.

Birley: We find little
african drinking cups,

We find couscous pots.

I mean, couscous hasn't
been locally available

For about 1,900 years.

Narrator: And among the
most sought-after products

Was garum.

Birley: Garum is just a
fundamental part

Of the roman diet,

Particularly the
mediterranean diet,

And anybody who's come
from that part of the world

Would require it as
part of their food.

Narrator: Records have
revealed the popularity of garum

Across the empire.

And the newly discovered
remains off the tunisian coast

Reveal neapolis became the
realm's biggest producer

Of this essential roman food.

But the city sat on
the southern boundary

Of the roman world,

Hundreds if not
thousands of miles

From many of its
would-be customers.

Fortunately for the
city's garum-makers,

Neapolis was part of one of
the greatest supply chains

The world had ever seen.

Birley: They've got
something called

The military annona system.

(ship crackling)

Imagine just a
giant conveyor belt

Which starts in the core of the
empire in the mediterranean,

It winds itself around like a
snake all the way to the edge.

Narrator: The romans invented
a mass distribution system,

Picking up and dropping
off goods in bulk

And transporting them from
the very heart of the empire

All the way to its
outskirts and back again.

Birley: You could ask
for practically

Anything that you'd want

From any part of the empire

And some warehouse not
too far away from you

Would have it there for you.

(dramatic orchestral music)

Narrator: Experts believe
the garum producers of neapolis

Tapped into this
giant trade network.

At the national
museum of denmark,

Dr. Athena trakadas
has been studying

The production and distribution
of ancient fish sauces.

She believes it's
possible to find out

Where neapolis's garum went

By tracking down its amphora,

The ceramic jugs
it was packaged in.

Trakadas: Amphora
are very useful

Because not only are
they durable,

The shape of an amphora
lets an archeologist know

Where it was manufactured.

It's very distinct,

It's like the coca cola
bottle of antiquity.

Narrator: Neapolis' amphora
are clearly recognizable

By their shape and insignia.

Dr. Trakadas thinks
it's possible

To map out the
product's movements

Thanks to one surprising type
of archeological evidence:

Shipwrecks.

(water gurgling)

Trakadas: With a shipwreck you
have a time capsule.

For archeologists,
it's advantageous

Because you can really
get a sense of commerce.

So you know at one point in time

What things were
going where and when.

Narrator: The discovery
of roman shipwrecks

Has been the key to knowing

Where neapolis
products were headed

And what route they were taking.

(dramatic orchestral music)

Trakadas: We see them along the
west coast of Italy,

In southern gal,
what is now France,

Into the iberian peninsula, as
well as western north africa,

So a wide distribution
throughout

The western mediterranean.

Narrator: This
vast distribution

Went far beyond the
shores of tunisia.

It's evidence neapolis mass
produced a quality sauce

That was in extremely
high demand,

Propelling it to
the very pinnacle

Of its wealth and influence
by the 2nd century ad.

But the city's success
would be short-lived.

(thunder roars)

An apocalyptic
storm was gathering

Both for rome and for neapolis,

And the capital of garum
would soon succumb to the sea.

(waves crashing)

(thunder booming)

A powerful storm off
the coast of tunisia

Has exposed the underwater ruins

Of a vast section of the
roman city of neapolis.

Its discovery has revealed
neapolis was once a thriving hub

On the empire's trading routes

And the roman world's
largest producer of garum,

A fish sauce that
was an essential

Part of the roman diet.

But neapolis then
disappeared from history.

And today, the majority of
its industrial heartland

Lies submerged by
the mediterranean.

(dramatic orchestral music)

But why did it sink
below the waves?

(thunder roars)

A force of nature revealed
this part of neapolis,

So could something
similar have destroyed it?

(ocean waves crashing)
(gentle orchestral music)

Earth scientist dr. Chris
jackson has been investigating

If a natural disaster
hit the mediterranean

Around the time neapolis
disappeared from history,

And he's discovered the area

Has always been prone
to catastrophic events.

Jackson: The mediterranean would
be a beautiful place to live

But it's also potentially
a very dangerous place.

We have an area of
very active tectonics,

So this is where the plates
are moving past each other,

(earth rumbling)

And that means this area
is prone to earthquakes.

And if you have earthquakes,

You also have the potential
for giant landslides.

(rocks thudding)

And then on top of that,

Because we have plates
going beneath other plates,

We also can generate
giant volcanoes as well.

(volcano booms)

Narrator: A massive
earthquake close to neapolis

Would have the potential
to destroy the coastline.

But there are no
historical records

Of quakes in this part
of the mediterranean

At the time part of
the city disappeared.

Jackson: We know that
this region,

Although it was subject
to very small earthquakes,

It wasn't subjected
to the big earthquakes

Which can cause cities
to crumble to the ground.

(ocean waves crashing)

Narrator: Another
theory that may explain

Why the harbor front
is now underwater

Is an increase in the
level of the mediterranean.

Jackson: The rise of sea level
could have just flooded

Half of the city,

But we know that
over this time period

Sea level has not risen
by enough to be the cause.

Narrator: So if it
wasn't an earthquake,

Landslide, volcano, or
rise in water levels

That submerged part
of neapolis, what did?

(dramatic orchestral music)

Dr. Darius arya
believes there is a clue

In a catastrophic event

That happened 1,200
miles away from neapolis

In alexandria, egypt.

It's here that roman
historian ammianus marcellinus

Recorded a cataclysmic
natural disaster

Hitting the egyptian
city in 365 ad,

(water gurgling)

Submerging many of
its finest buildings.

Arya: "the solidity of the
earth was made to shake

"and the sea was driven away.

"the waters returning
when least expected

"killed many
thousands by drowning.

"huge ships perched
on the roofs of houses

"hurled miles from the shore."

Narrator: For dr.
Arya, this description

Of a massive wall of
water hitting the land

And destroying
everything in its path

Can be only one thing.

(dramatic orchestral music)

Arya: He's describing a tsunami.

Narrator: A tsunami
so deadly and powerful

It completely
engulfed alexandria.

If the account is true,

Could it also have
annihilated part of neapolis?

Dr. Jackson believes
there may be a link.

Jackson: Tsunamis are often
triggered during earthquakes

That push the water
up into the air,

And as the water
collum collapses,

That is the tsunami
wave rippling

And pushing away from the
epicenter of the earthquake.

Narrator: So
could an earthquake

Somewhere in the mediterranean
have caused a tsunami so big

It swamped alexandria
and neapolis?

(door squeaking)
(door rattling)

To find out, dr. Alina
polonia and her team

At the italian national
research council

Gathered dozens of core
samples from the seabed.

Polonia: This sample, which is
about seven meters long,

Is part of a sediment core

That we collected in the
eastern mediterranean.

Narrator: This
sample is a snapshot

Of how the sea gradually
laid down layers of sediment

Over 10,000 years.

Polonia: The sedimentation rate
for this deposit is very low,

It's 0.1 millimeter per year.

That means that one
centimeter represents

100 years of sedimentation.

Narrator: But one
section of the core

Revealed a layer of sediment

Unlike anything the team
had ever seen before.

Polonia: This point to this
point have, more or less,

Two meters of sediments that
were deposited instantaneously,

And I mean, in hours.

Narrator: Normally, a
century's worth of sediment

Is less than 1/2 an inch thick.

But this massive layer of sludge

Was dumped on the sea
floor almost instantly.

In some parts of
the mediterranean,

The team estimates it
was up to 82-feet thick,

Over a billion times
larger than normal.

Polonia: This type of deposits,

The triggering
mechanism responsible

Is very peculiar and very rare.

(dramatic orchestral music)
(water gurgling)

Narrator: This
huge dump of sludge

Could only have come from
a massive upsurge of water

Dragging sediment from
the bottom of the sea

And dumping it elsewhere.

To the team, it is
evidence of a mega tsunami

Of unparalleled
size and strength.

(gentle orchestral music)

Carbon dating revealed
when it happened.

Polonia: We have found an
age for this deposit

That is in good agreement
with the 4th century ad.

Narrator: The date of
the mega-tsunami is a match

For the historical account of
the destruction of alexandria

In 365 ad.

But what triggered it?

The team traced the source
of the huge dump of sediment

To an area just off
the coast of crete.

They now believe this
was the epicenter

Of a massive ancient
seismic event.

Polonia: It was
possible to define

The magnitude of
this earthquake,

Which is 8.3 to 8.5, so it's
a very large earthquake.

(ocean waves crashing)

Narrator: 8.5 on the richter
scale is almost as strong

As the quake that sparked the
2004 indian ocean tsunami,

Which spread over 3,000
miles from its epicenter,

Killing nearly 1/4
of a million people.

(water whooshing)

(gentle orchestral music)

It means the sheer
force of the 365 quake

Was powerful enough to
trigger a deadly tsunami

That not only hit alexandria,

It also struck neapolis.

Polonia: We are dealing with
a very exceptional

And catastrophic event
which should have produced

Devastating effects
along the coasts.

(water whooshing)

Narrator: The evidence
suggests the tsunami

Could have created untold
destruction in neapolis,

Perhaps even
submerging its harbor.

But for some experts, the sudden
death of a prosperous city

Because of a tidal wave
doesn't quite ring true.

Because it took a lot
to knock out the romans.

The suspicion is
backed up by evidence

Life continued in neapolis
for centuries after 365 ad.

Arya: Romans were extremely
resilient people.

And when their
cities were struck

By fires, floods,
and earthquakes,

They rebuilt, they shored up
monuments, they reconstructed,

They recycled what was
able to be salvaged.

They didn't give up very easily.

Narrator: So, what ultimately
led neapolis' dwellers

To finally surrender
the city to the sea?

Experts now suspect
the devastating tsunami

Wasn't the direct cause
of neapolis' demise.

But it was the
beginning of the end.

(ocean waves crashing)

(dramatic orchestral music)

Experts are piecing together

The story of the lost
city of neapolis,

A bustling roman port on the
tunisian coast that grew rich

By producing the empire's
most essential food:

A fish sauce known as garum.

Today, a large
section of neapolis

Lies under the mediterranean.

What could have
caused its demise?

Geological evidence
suggests the area was hit

By a cataclysmic
tsunami in 365 ad.

But archeological finds have
revealed that, astonishingly,

The city survived.

Lowe: We know that it
continued to prosper

Because we've got inscriptions
from the 5th century ad

And we have 6th-7th century
burials in neapolis,

So there's occupation
still going on.

Narrator: Now, new clues
suggest the 365 tsunami

May indeed have caused
the end of neapolis,

But in a much more
gradual and insidious way.

(water gurgling)

The evidence comes
from sediment samples

From the time of the tsunami.

When dr. Alina polonia
analyzed the cores

Taken from the deepest
depths of the mediterranean,

She was astounded to discover
marine plants and organisms

Normally only found
in shallow waters.

Polonia: These samples show
displaced species

That live in very shallow water,

From zero to 10
meters of water depth,

Transported down
to 4,000 meters.

Narrator: These
coastal water species

Could never survive in the deep.

So why were their remains
found 13,000 feet underwater?

Dr. Polonia believes it's
evidence the 365 tsunami

Not only devastated the
north african coast,

It also wreaked
havoc under the sea.

Polonia: The tsunami reaching
regions with shallow water

Amplified its wave.

The wave drained
material from the coast

And transported it
backwards in the ocean.

Narrator: As the
tsunami hit the shore,

It churned up the
coastal shallow waters

And dragged their contents
back into the abyss

In a giant underwater landslide.

As the sediment was sucked away
from the scoured coastline,

It left behind countless
tiny spaces and gaps

Amongst the coast's
remaining earth and sand.

Earth scientist
dr. Chris jackson

Believes the
underwater landslide

Would have completely
destabilized

The ground neapolis
was built on.

Any further earth tremors would
push the city's water table

Into the gaps created by
the displaced sediment,

Turning the shore into a
soaking bed of sand and silt

In a phenomemon known
as liquefaction.

Jackson: Most people would be
familiar with liquefaction

From being on the beach

When they stamp up
and down on wet sand

And they sink down
into the earth.

Narrator: Sinking
into sand on a beach

May be harmless
for a vacationer.

But, as dr. Jackson
demonstrates,

For a city, it can be deadly.

Jackson: What I've got in my
hand here is a building.

It's actually a brick.

But you can see if we
put it down onto the sand

We can see it kind
of settles in.

Even with a bit of gentle
pushing it's not sinking at all.

Narrator: The ground
above the waterlogged sand

Appears firm enough to support

The weight of the
heavy building.

But just like the
earthquake-prone tunisian coast,

This ground's
stability is undermined

If the terrain is
hit by a tremor.

Jackson: So here I am
with my earthquake,

And I'm just gonna gently
tap the side of this.

(hammer thudding)

Narrator: As the tremors
shake the saturated ground,

Water is forced up through
the gaps in the sand.

Jackson: Wow, and all of a
sudden you can see the water

Pooling on the top surface
and bubbles all over the top.

(hammer thudding)

Narrator: The water
pushes the sand apart,

Reducing its
structural stability.

Jackson: Now half of the brick
has sunk down into the sand

And is lost forever.

When the ground is shaken,
the sand grains can't compact,

So we go from having sand

To actually water with
sand grains floating in it.

Just imagine if this
brick was a house.

(water gurgling)

Narrator: Dr. Jackson believes

That the massive tsunami

May not have submerged
neapolis' harbor,

But it weakened the
ground underneath it.

Any subsequent tremors
would have caused

The now destabilized coastline

To start sinking into the sea.

(gentle orchestral music)

And geological evidence suggests

That in the centuries that
followed the 365 disaster

Tunisia suffered a barrage
of small-scale earthquakes.

Jackson: The cumulative effect
of those small earthquakes

Could be to really, really
damage the infrastructure

In one particularly location.

(earth rumbling)

Narrator: It
seems the 365 tsunami

Set off a slow and painful
death for neapolis.

And in the decades and
centuries after it,

Every small quake
caused the city

To sink further and further
into the mediterranean.

But according to historians,

This wasn't the only reason
for the city's decline.

(feet stumping)

The western roman empire
was also weakening,

The result of a
series of invasions.

In 476 ad, it finally
disintegrated,

And its vast trade
network ground to a halt.

Just over a 100 years after
the devastating tsunami,

Neapolis was on its own.

Lowe: Once the ability
of the roman empire

To keep the sea lanes
open breaks down,

The bottom falls out
of international trade

And the world shrinks.

(pebbles crackling)

Narrator: As the
fortunes of rome faded,

The trade network that fed
the romans' demand for garum

Also began to falter.

Birley: As that starts
to dissolve,

Your market starts to disappear.

And suddenly, what was a really
sustainable good business

Starts to look very
shaky on its foundations.

That story was repeated
not just in north africa

But right around the
mediterranean provinces

And other provinces
of ancient rome.

Narrator: Dwindling demand,
a disrupted supply chain,

And an industrial
complex slowly sinking

Into the waters of
the mediterranean

Meant neapolis's
fate was sealed.

The city and its
tanks were abandoned.

Arya: When we look at the
history of neapolis,

Its rise and eventual decline,

It really does parallel
with the history of rome.

When that tapers off,

Then the fortunes of
neapolis are gonna taper off.

(dramatic orchestral music)

Narrator: The city
of neapolis grew rich

On a humble fish sauce

That became an international
statement of roman identity.

Its wealth and importance

Allowed it to survive
a mega tsunami,

But it could never recover
from the convulsions

Sweeping across
the ailing empire.

As the remains of the harbor
sank beneath the waves,

Neapolis slipped from memory.

But now its stunning
re-discovery

Reveals how this lost city's
spectacular rise and fall

Echoes the fortunes of
the entire roman empire.