Unearthed (2016–…): Season 11, Episode 4 - Sunken City of Helike: The Hunt for the Real Atlantis - full transcript

Helike,

one of the greatest ports
of classical Greece.

This entire city, just like
fabled Atlantis, vanishes

to all but legend
for over 2,000 years.

Now, pioneering archaeologists
believe they have

unearthed the ruins of
this ancient metropolis.

The investigation
into Helike's fatal

final days inspires
cutting-edge experiments

to test the true cause of
the city's disappearance.

Does a single wave
devastate Helike?

Or does the earth itself consume
its sacred stone structures?



And could Helike's rediscovery
lead the way to

the most famous lost city of
all, Atlantis?

To solve these mysteries,

we digitally reconstruct
this bustling ancient capital.

We rediscover the lost monuments

once worshiped
by the city's residents

and crack the mystery of why
Helike is hidden for so long

to unlock the true story
of Greece's real-life Atlantis.

50 miles from Athens is
Greece's Peloponnese peninsula.

Somewhere along this coast lie
the remains of Helike,

one of the great cities of
ancient Greece.

Homer's Iliad describes
its proud people

going into battle under
King Agamemnon

during the siege of Troy.



2,400 years ago, the city
disappears overnight.

Ancient texts describe
a walled city-state that

thrives as Greek culture
and military might dominate

the Mediterranean.

Its people worship
the almighty Poseidon

and construct a temple
and sanctuary in his honor,

as well as a giant bronze
statue of the sea god.

In 373 BCE,

a disaster destroys the city,

and like Atlantis,
Helike disappears.

What happens to the city,
and where is it today?

One of archaeology's greatest
quests is to find Helike

and unravel the mystery of
the city's fatal final days.

Dora Katsonopoulou

has searched longer than any

other investigator to unearth
this legendary metropolis.

Luckily, she has help.

An ancient eyewitness leaves
clues to

the location of
the great lost city.

He spots Helike's ruins,
five centuries after

its destruction,

and records the distance
to two local landmarks.

First is the still-standing
city of Aigion to the west.

He also states
the ruins are 30 stadia,

3 miles from a place
known as the Cave of Herakles.

Dora measures from
the two fixed points.

Helike's search area is today

roughly 2/3 land and 1/3 sea.

It means the city could now lie

underwater in the nearby
Gulf of Corinth.

An eyewitness reports

Helike lies underwater

150 years after its destruction.

The sacred bronze statue
of Poseidon still stands,

holding a half-horse,
half-fish mythical beast,

the hippocamp.

It snags on fishing nets
passing above.

Four hundred years later,

another eyewitness describes
the city.

Badly corroded from salt,

it remains a well known
local landmark.

Does Helike lie hidden
beneath the water today?

Starting in the 1960s,

guided by the ancient accounts,

Dora and others search
for the lost city.

Experts use sonar,

divers,

and undersea drills to
systematically probe

the seabed of
the Gulf of Corinth.

They return empty-handed.

Dora refuses to
give up on the hunt for Helike.

She re-examines the ancient
eyewitness's description.

The Greek word "poros"

means a narrow stretch of water.

Other experts assume
this stretch of

water must be
the Gulf of Corinth.

Dora thinks if the eyewitness
spots the statue there,

he would use its proper name,

the Gulf of Corinth.

It must lie beneath
a different stretch of water.

If Dora's theory is correct,

she'll disprove some of
the world's

greatest archaeologists.

The problem is the lagoon has
long since disappeared.

Where might the lost city
lie today?

And can its ruins reveal what

happens on Helike's
fatal final day?

The great city of
Helike is destroyed in 373 BCE.

Its ruins are last
seen underwater

nearly 2,000 years ago.

Fresh analysis of ancient
eyewitness reports suggests

the city may not be lost
beneath the sea.

It may lie under an inland
lagoon that has vanished.

Dora's team searches
for the lost lagoon

and the city beneath.

They drill 99 boreholes in

the region outlined by
the ancient eyewitness account.

Lead Geologist
Ioannis Koukouvelas examines

mud cores from the boreholes.

The green tint
dates this sample layer

to 2,400 years before
the present day,

the time of Helike's
great disaster.

The layer also contains
the smoking gun

the team is searching for...
Signs of human occupation.

The ceramics
could be from Helike.

The team excavates around
the most promising boreholes.

Beneath 10 feet of mud,

they uncover the remains of
an ancient dwelling.

Inside, they find a small clay
sculpture of a female idol,

fragments from a shattered vase,

and Greek coins, one featuring
a pair of dolphins.

The finds reveal a settlement
that dates to

the 4th century BCE.

If this is ancient Helike,

where is the evidence for
the lost lagoon?

A clue lies 5 feet
above the ruins...

A dark layer of sediment.

The finds suggest Dora's
controversial theory that Helike

lies under a lost lagoon
could be correct.

But the team needs proof

the dark layer corresponds to
the bed of an ancient sea lake.

Ioannis examines
the mud core close

up at the University of Patras.

Ioannis scrutinizes
the layer's contents.

His team
searches for any tiny shells.

They might not be much larger
than grains of sand.

For precise identification,

the team creates images
using an electron microscope.

These are creatures
called ostracods,

particular species that prefer
to live in the mix

of salt and fresh water
found in a lagoon.

The presence of these ostracod
species confirms Dora's theory.

Helike was covered by a lagoon,

which then itself disappears

thanks to this area's
ever changing landscape.

Local rivers erode
nearby mountains.

And fill with huge amounts
of sediment.

Over many years,
the rivers dump this debris

once they reach
the coastal plain.

The buildup of silt
produces new banks

and channels, drastically
changing the local landscape.

It's likely the lagoon
above ancient

Helike gradually fills up
with river sediment.

The sea lake turns into dry land

and conceals Helike completely.

Dora and the team's
detective work

finally solves
a centuries-old mystery.

They found Helike.

For 20 years,

the team digs deep
trenches through

the sediments of the flat
coastal plain.

They unearth several pockets
of settlement that

span more than 2,000 years
of occupation.

What can archaeology
reveal about

Helike's status in
ancient Greece?

And could this help pinpoint
the source of the Atlantis myth?

Helike, Greece,

a long lost ancient city,

now rediscovered by Dora
Katsonopoulou and her team.

Among the ruins of Helike,

archaeologists unearth
two identical coins.

They feature important clues
about the ancient lost city.

On one face,
a laurel wreath surrounds

two dolphins swimming either
side of a trident spear.

On the other, the head of
the god Poseidon,

next to a single word in Greek,
Helike.

What can these coins and the god

depicted on them reveal
about the city?

The great poet Homer,
four centuries before

Helike's destruction,

remarks on great sacrifices
made in Poseidon's honor.

The locals choose
this particular god

because Helike is a port city.

The citizens' fortunes
depend on the sea

and, they believe, on the moods
of its chief deity.

Poseidon is the brother of Zeus
and Hades.

He carries a three-pronged
spear called a trident

and is one of the most
important gods

in the Greek pantheon.

Poseidon reigns over
all rivers and seas,

leaving Zeus to rule
the heavens and Hades

the underworld.

His bad temper generates
storms and floods.

With a strike of his trident,
he sets off earthquakes.

Superstitious sailors make
offerings of animals to

appease Poseidon's wrath
before setting out to sea.

Dora investigates exactly how
important the port

of Helike is
in the ancient world.

In recent excavations,
the team unearths over

a hundred coins.

Almost all of them are not
minted in Helike.

Coins from visitors far

and wide reveal Helike's
widespread importance.

It's the major stop off
point for

ships traveling along
the Gulf of Corinth.

This traffic and trade
allows Helike's stature to

increase ever further.

In its golden age,

Helike leads an alliance of
12 city-states

in the Achaea region of
ancient Greece.

The city plays a leading role in

Homer's epic story of
the siege of Troy.

Helike's cultural influence

spreads across
the Mediterranean,

as it establishes colonies
in Italy and Asia Minor.

Helike's sanctuary of Poseidon
attracts pilgrims from far

and wide,

spreading the city's fame
across the ancient world.

However,

Helike's high status
is unstable.

Ioannis Koukouvelas

believes there's a second reason

Helike's citizens choose to
worship Poseidon.

The bad-tempered god of
the sea has another name,

the earth shaker.

Helike prospers thanks

to its links to Poseidon,
the sea god,

but as god of earthquakes,
he brings destruction.

What sequence of events causes

the thriving city
to vanish overnight

in 373 BCE,

and is there any escape
for Helike's residents?

The ancient city of Helike

disappears in 373 BCE.

In the hills above
its buried ruins,

Ioannis Koukouvelas searches
for the cause

of the city's disappearance.

The exposed rock reveals clues

to the area's recent
geological past.

There are several steps
called offsets

where layers of sediment
suddenly drop downwards.

The offsets reveal
this coast is prone

to one of nature's
most destructive forces,

earthquakes.

The larger the offset,
the greater the tremor that

causes it.

One of
these large offsets matches

the strong earthquake that
spells disaster for Helike.

On a winter's night of 373 BCE,

an earthquake of
a magnitude above

6 on the Richter scale
strikes Helike.

According to
ancient eyewitnesses,

immense columns of flames
erupt from cracks in

the ground... their light shines
across the city.

Tremors rock the buildings,
reducing them to rubble.

Then, astonishingly, the whole
of Helike sinks into the ground.

Can this terrifying tale of

the earth engulfing entire
buildings be true?

Christian Malaga Chuquitaype
of Imperial College

London investigates.

Is it possible
for full buildings

or structures to be swallowed
by the earth?

So what I'm going to do here
is offer you

a demonstration of what
happens when an earthquake hits

saturated soil.

This high-tech shaking
table replicates what happens

when an earthquake strikes...
Like many coastal cities,

Helike is built on sandy soil
just above the water level.

I'm just, um, mixing,

allowing the water to go deeper.

Christian places
model structures into

the tank, which contains sand
saturated with water.

The soil at this
stage, although it has water,

it's able to sustain
the weight of the structure

and keep it in place.

Ancient Helike's
buildings are well supported,

but the saturated ground is
vulnerable to seismic activity.

Christian's table replicates
an earthquake's

rapid back and forth shaking.

So it's going now.

The earthquake
first knocks buildings over.

Then they start to sink
into the ground.

What happens is that
the water pressure inside

the sand starts to increase,
and at some point,

it breaks all the capacity
that the sand has to sustain

the structures
on top of it... the sand is

unable to sustain
the load of the buildings.

This phenomenon is
called soil liquefaction.

The tremors cause
underground water

to overcome the sand's
supportive power.

The science shows
model buildings will partially,

but not completely, disappear
into once solid ground.

Five days before the disaster,
animals flee the city,

perhaps sensing tremors in
the ground beneath their feet.

On the fateful night
the earthquake rocks Helike,

soil liquefaction sucks
buildings into the ground.

Few citizens can flee
the annihilation.

Ten Spartan ships anchored
in Helike's harbor

are dragged down into the ocean.

A 2,000-strong rescue team
from neighboring

cities searches for survivors,
to no avail.

Christian's first
demonstration shows

buildings can be partially
swallowed by sandy soil.

But to test whether
liquefaction can consume

the entire city,
as ancient sources claim,

he sets the shaking table to

the equivalent of 8 on
the Richter scale.

This matches some of
the strongest earthquakes

ever recorded.

I'll start.
Yep.

The buildings begin to sink.

But as they do, the sand
beneath compresses.

Eventually, the ground firms up

enough to bear
the structure's weight.

You can see that the building
here, it's not fully sinked.

Even if you have a very,
very strong shaking,

I would expect buildings
to tilt, buildings to break,

and some parts of them
to be swallowed,

but the idea of whole buildings

just completely disappearing
into the ground

is probably a bit of
a literary freedom.

Liquefaction very likely

plays a part in Helike's fate.

But liquefaction alone
can't cause an entire city

to disappear.

What really wipes out Helike?

Will evidence on the ground

match the extraordinary
ancient accounts?

In 373 BCE, Helike,

one of the great cities of
ancient Greece, disappears.

A team of scientists seek to

piece together
its fatal final days.

After the earthquake,

ancient texts report
a rapidly rising sea.

Then they state water
completely submerges the city.

Ioannis Koukouvelas

suspects the accounts describe
another natural phenomenon.

When Dora's team
examines Helike's buried ruins,

they spot something unusual
about the settlement.

A set of stones lies scattered
at ground level.

The stones once formed
the lower section of a wall of

a house... a powerful blow
has pushed it over.

This could come from
a natural phenomenon.

Could this be evidence
that a tsunami

provides the knockout blow
that seals Helike's fate?

Ioannis Karmpadakis models
Earth's biggest waves

in these 75-foot-long tanks at
Imperial College, London.

Ioannis wants to find
out whether

a tsunami could cause Helike's
pattern of destruction.

A tsunami starts when
an underwater earthquake

or landslide stirs a large
volume of water.

In deep water,
the wave is small.

But as the tsunami squeezes
into the shallows, it changes.

The initial tsunami
isn't enough to push down walls.

There is a secondary
phenomenon at play.

Ioannis adds loose material
to represent

debris created by
the earthquake.

The incoming wave
uproots this debris.

The wave retreats,
but it's now loaded with

debris, ready to smash
anything in its way.

The experiment
explains why the destroyed

wall falls towards rather than
away from the incoming sea

and proves it is very possible
a tsunami strikes Helike.

Now, Ioannis investigates if
a tsunami can

be big enough to engulf
the entire city,

as the ancient texts describe.

The geological evidence
suggests Helike's earthquake

peaks at around 6.5
on the Richter scale.

The waves in
the previous experiment

match massive earthquakes,

around magnitude
8 on the Richter scale.

A smaller earthquake
reduces the height of the wave

and therefore the distance
the water can reach inland.

Enough to damage some buildings

but not to swamp
the entire city,

as the ancient texts describe.

Rather than a single
devastating wave,

the evidence shows
the ancient accounts

miss or misinterpret a more
complex chain of events.

The earthquake creates
a 6-foot-high tsunami

that wipes out the boats in
Helike's Harbor.

As the destructive wave
washes inland,

it destroys the walls of
some buildings.

The tremors also break a natural

river dam in the mountains
behind Helike,

releasing millions of gallons
of fresh water

onto sections of the city.

Part of Helike's coastal plain
drops several feet.

This allows seawater
to submerge all

but the tallest buildings
and trees.

Dora Katsonopoulou's team

believe the influx of
fresh and saltwater creates

the lagoon that smothers
most of Helike, until it too

eventually disappears.

At her latest dig site,

she hunts for clues to how
much of Helike survives.

Okay. Good.

These ruins lie
just a third of a mile

from flooded parts of
the ancient city.

They date to a period of
reconstruction after

the earthquake.

Ancient workers dye
cloth in these basins.

This site reveals
not all of Helike

and its people are overwhelmed
by the disaster.

The lagoon drowns
the earthquake-damaged remains

of Helike's Poseidon statue
temple and sacred sanctuary.

But other parts escape.

The mystery of

Helike's fatal moment is solved.

Ancient writers exaggerate
a moderate earthquake that

drags Helike's most
famous monuments

into the depths of a lagoon,

where they remained to astound
fishermen for 500 years.

On the outskirts of Helike,

life resumes soon after
the disaster.

One final question remains.

Why does this lost city's
fate so

closely mirror the legendary
tale of Atlantis?

Could the life story of
Atlantis's creator provide

some clues?

In 373 BCE, an
earthquake triggers a cascade

of events that submerge
the ancient city of Helike.

The city's tragic end
echoes the story of

the most famous lost kingdom
of all, Atlantis.

The story of Atlantis
is something we all heard

as children... it's this story
that captivates us,

because not only
is it a lost civilization

that we want to uncover,

but it's also a civilization
that's submerged,

destroyed by tsunami
and earthquake.

Jasmine Elmer
researches real life origins

of ancient myths.

She investigates whether Helike
could be

the inspiration for the great
lost city of legend.

Her research starts
with ancient texts.

Around 360 BCE,
Greek philosopher Plato

describes the lost land
in two works...

The Timaeus and the Critias.

So this is where we first see

the actual words in the Greek,

which means the island
of Atlantis.

It's the first time that Plato
actually mentions Atlantis.

Plato's Atlantis
story is an allegory,

a fable he concocts to teach
a moral lesson.

However, actual locations
and events may allow

him to inject some realism to
the tale.

I think it's a really good
exploration to consider all

those different points of view
and the...

And the contemporary
historical events that are

going on to see if there is
an inspiration there for Plato.

The first clue Helike
could inspire Atlantis is that

citizens of both places are
devoted to the same god.

And in the center of
the island is the temple

to Poseidon.

And the cult of Poseidon
is obviously

a really important part of
Atlantean culture.

And that's really similar in
some ways to Helike, because

the cult of Poseidon there

was dominant and well known
across the Greek world.

Plato writes
the gods destroy Atlantis as

a punishment for the arrogance
of its citizens.

This tale of retribution echoes
a story told about Helike.

Some citizens from Helike's
colony in Asia Minor traveled

back to their homeland on
the advice of an oracle.

They make a sacrifice
to Poseidon

and reveal a plan to take back

sacred relics that belong to
their forefathers.

The inhabitants of Helike are

affronted and murder
their visitors.

Poseidon is angered
by this outrage.

He punishes Helike
and its impious citizens with

a cataclysmic earthquake
and tsunami.

The connections between Helike
and Atlantis are clear.

Both worship Poseidon.

Both are destroyed
and then disappear.

There was an earthquake,
there was a tsunami,

there was a flood, and also
there is this sort of odd

description of sinking
into the earth

in the same way that you get
a kind of

liquefaction that's going on
as part of the Helike disaster.

The final clue that
Plato has Helike in

mind is when he writes
the legend of Atlantis.

Helike is the disaster
that happens only

about 15 years before
he writes his dialogues.

So it kind of makes sense
that this is an event,

a contemporary event
that is happening,

it would have been a very well
known disaster.

It makes sense that Plato would
perhaps have knowledge of that.

Jasmine believes it's possible

Plato recycles what he hears
of Helike

to bring to life his own
disaster story.

In the long search for Atlantis,

the trail strongly leads
towards one real life lost city.

After a decades-long quest,

the story of Helike
can finally be written.

One of the great ports of
ancient Greece,

it rises, thanks to its
Poseidon cult, to dominate

the Gulf of Corinth.

The city falls in
the earthquake of 373 BCE.

Its sanctuary and statue
disappear underwater for

five centuries,

then vanish completely for
almost two millennia

until Helike's
rediscovery today.