Original subtitles

NARRATOR: Pirates, gangsters, villains and the worst of humanity.

Swallowed up by the sea.

But why?

Were they ripe for the wrath of God?

Or are there deadly natural forces at work?

What if, you could drain the ocean to reveal the secrets of the seafloor.

Now, powerful new technology can do just that.

Digital photos and sonar scans give us remarkable new

insights into a world beneath the sea.

What apocalyptic disaster wiped out the Pirate city of Port Royal?

JON: It's a city that was literally swallowed by the sea.

And what are the dangerous forces that made Alcatraz, the Rock,

the most infamous prison on earth.

JOHN: The conditions surrounding this island is what really made it an

escape-proof prison.

Drained dry, we reveal the extreme geological forces that led

to the demise of so much wickedness.

NARRATOR: Deep beneath the waves, is a reminder of the earth's violent beginning.

Through the use of cutting edge technology we can reveal the secrets of the sea floor

in astonishing detail.

And expose the shaky ground on which we all live.

In the 17th Century, Port Royal, on the south coast of Jamaica,

was an English stronghold at the heart of the Spanish empire.

Dominating what would become Kingston Harbor from the end of a long spit of land.

JON: If you've seen the Pirates of the Caribbean movie,

the first town you go to, where we meet Jack Sparrow is Port Royal.

NARRATOR: Grown fat on the profits of piracy and

slavery, Port Royal was a city of almost 8,000;

the ultimate boom town of a new world.

But it was also known as the wickedest city on earth.

It certainly had more bars and brothels than any other city

in the whole of the English colonies.

-Well the port, indeed, is very loose in itself; it is now more ruled than our Sodom.

Filled with all manner of debauchery.

NARRATOR: On June 7th, 1692, disaster struck Port Royal.

A massive earthquake wiped two thirds of the city off the map; sending it to the bottom

of the sea.

Today, archaeologist, Jon Henderson, an expert in sunken cities, will use new

technology to discover just how the disaster unfolded.

Port Royal sank so fast that it took its secrets with it.

-This is a true sunken city; but not only that, it's a catastrophic site.

It went down so quickly that it sealed a moment in time.

It's sometimes called the, the Pompeii of the new world.

It's now underwater for us to discover and that's really rare in archaeology.

NARRATOR: Jon's mission is to rediscover the sunken city and recreate a precise digital

model of its ruins.

Data that explains how the city tore apart, in two minutes of terror.

It's a huge challenge, but if it works, we can virtually drain the ocean...

Strip away millions of gallons of water and bring the sunken city of Port Royal back into

the light of day.

Draining the sea beyond Port Royal may explain why it became a pirate powerhouse.

It's all down to its location.

Right at the entrance of Kingston Harbor.

Pulling the plug on these Caribbean waters, reveals one of the largest natural harbors.

At ten miles long and two miles wide, it's large enough to shelter hundreds

of ships from the hurricane whipped tropical seas.

Better still was the long finger of land on which Port Royal was built.

JON: One of the things we'll see is the spit coming out into this very deep harbor.

NARRATOR: Its steep sides made it the perfect location to dock ships.

JON: You had deep water on either side, large ships could come up and get very close to

the shore very quickly.

NARRATOR: This might seem like an ideal spot to build a port; but made of constantly

shifting sand, the spit would be Port Royal's undoing.

JON: The main problem is, there is no solid geology down there for a very long way; so,

in an earthquake, when that starts to shake, you're in trouble.

-I very much doubt that anybody in Port Royal

realized they were sitting on a time bomb.

NARRATOR: Jon Henderson is here with,

photographer Simon Brown to photograph the sunken city.

With bad underwater visibility Simon must get as close as possible to the ruins

and take thousands of images.

After three days the many photos have been compiled into a 3D representation of what

lies on the seabed.

-Okay Simon, show me what we've got then.

-It's not been easy, but we've captured quite a lot of building five.

NARRATOR: Building five may once have been a grand family home.

All that remains of it now is one room.

Showing up in unprecedented detail.

-I mean, this looks fantastic, given the conditions you were working in.

I mean, we can see we've got the wall, you can actually see the courtyard next to it.

You can see the fire-pit.

You can see the low walls.

This is great; we can actually see the individual bricks themselves.

For me, what's exciting is, you can show that to someone and they can instantly see

what's actually down there.

I didn't think you would get results as good as this.

NARRATOR: Jon's mission is delivering spectacular results.

JON: We're beginning to reconstruct, for the first time in 300 years really,

what exactly's there.

NARRATOR: Now we can examine the most famous pirate city from every angle.

And shine light on the extraordinary disaster, that sent thousands of people and

hundreds of houses to the depths.

But clues to its wickedness still lie hidden in darkness.

Since the 1950s, three archaeology expeditions have sifted Port Royal's

underwater ruins, to uncover its pirate past; and in the

1980s, a team discovered part of the fabric of the city itself.

-During that ten years, we excavated five buildings pretty much completely.

It was the most exciting excavation I've ever conducted.

NARRATOR: Today, we use science to map these discoveries right across the

sunken city.

Thousands of relics from a lost world.

All clues to Port Royal's cataclysmic final day.

JON: Because this is a catastrophic site, it's sealed a whole range of goods that

were being used at a particular moment in time.

NARRATOR: Each one is an insight into the 17th Century world of Caribbean pirates.

JON: So we can get actual snapshots and glimpses into daily life.

NARRATOR: From pewter tableware, to Chinese porcelain and signs of

personal wealth.

RONALD: The archaeological record of Port Royal shows how quite rich it was.

Because, usually, towns in the new world are impoverished copies of those in Europe;

whereas Port Royal actually stacks up against the capitals of Europe.

NARRATOR: But how did Port Royal grow so rich?

The city was built from the wealth of stolen Spanish treasure.

In the 1650s, England and Spain were at war.

Jamaica, an English territory in the Caribbean,

lay surrounded on all sides by the Spanish Main.

From Florida, through Mexico and South America.

To gain the upper hand over the Spanish, the English enlisted the help of pirates.

JON: In 1657, the Lieutenant Governor of Port Royal actually invited the pirates

to come here and to act as a kind of unofficial defense force.

(screams)

RONALD: To the English government, pirates who attacked Spanish goods and

bring them to English ports, could be an asset.

NARRATOR: Pirates were licensed to raid the Spanish; at sea or on land.

They became known as buccaneers or privateers.

RONALD: What happens in Port Royal really is state sanctioned piracy.

NARRATOR: And in Port Royal, at the heart of the Caribbean,

the buccaneers were perfectly placed.

In striking distance of the main shipping routes between the new world and Europe.

RONALD: If the Spanish are gonna try and get anything home, they have to get it past

Port Royal; so it's rather like a fox sitting in the middle of a chicken coup full

of chickens.

NARRATOR: Port Royal became the buccaneering capital of the world.

By agreement, the English crown took a quarter of the plunder.

The rest was shared amongst the pirates.

RONALD: Among the very first buccaneering expeditions, 1659, the fleet brought back

the modern equivalent of $75 million.

The Spanish wealth that hits Port Royal in periodic waves is colossal.

NARRATOR: Massive injections of cash transformed this fortified outpost

into a boomtown.

The drained city exposes as many as 2,000 brick and timber houses, crammed into

Port Royal streets.

Home to a growing population of almost 8,000.

The crowded narrow streets would become a death trap when the earthquake struck.

JON: We're on a very enclosed, very overcrowded peninsula; we've got people living here

side by side, in two to four story dwellings.

When the earthquake struck, there was nowhere to run.

NARRATOR: From the thousands of clues uncovered from Port Royal's seabed,

there is one chilling piece of evidence of when the earthquake struck.

A 17th Century pocket watch; its hands long since rusted in the sea.

But closer analysis of the find reveals something intriguing.

JON: When it was x-rayed, it was seen that the hands had actually stopped at 11:43.

Now we know from historical records that the earthquake apparently hit just before

noon and this has been taken by some to say that the hands of that watched stopped

exactly when the earthquake struck.

NARRATOR: But what powerful natural forces set the earthquake in motion?

To find the answer, we're draining the ocean not just from Port Royal,

but from the whole of Jamaica, to uncover the source of the earthquake.

Hidden in darkness, thousands of feet beneath the water.

-As you drain the ocean from around Jamaica, what you can see is these giant furrows

in the seabed; they're fractal lights running east/west and they're faults, they're

earthquake fault lines.

NARRATOR: The faults form part of the boundary between two pieces of the earth's crust;

the North American Plate and the Caribbean Plate to the south.

Both constantly on the move.

-It's a place where the gradual motions of the plate either side get snagged,

stress builds up.

Essentially it's an earthquake zone.

NARRATOR: And Port Royal sits right in the middle of it.

-And in the case of 1692, that stress that had built up very, very gradually over

time, gets unleashed into this, this huge earthquake.

NARRATOR: As the stress in the earth's crust is released, it propels a powerful seismic

wave into the surroundings.

June 7th, 1692.

-Doomsday at Port Royal, begins like any other day.

There are daily prayers in the churches, business begins at sunrise.

JON: People were just going about their business.

NARRATOR: Travelling up to five miles per second, the seismic pulse was heading

straight for Port Royal.

JON: There's records of one guy about to go and have a sherry with the

Lieutenant Governor that morning.

There was no indication of what was about to come.

NARRATOR: Port Royal's alleyways and buildings were full of people.

Its wharfs and docks crowded with merchant ships.

IAIN: I think the first indication would have got is a bang, a noise in the north, in

the mountains and a kind of low rumbling.

JON: Well the records we have suggest there was three pulses from the earthquake.

IAIN: It was what's to come that was the real killer.

-For the shake was so violent, that it threw people down on their knees.

NARRATOR: Chasms opened up in the ground.

-We felt the ground shake and saw the bricks begin to rise in the floor.

-The ground heaved; it swelled like a rolling, swelling sea.

NARRATOR: People ran from their lives from the falling masonry.

(screams).

But the city offered no refuge.

IAIN: Port Royal was almost the worst case scenario; really tall buildings, made of

brick, with narrow streets.

So, if you're in those streets, it's almost impossible.

Your choice whether to stay in a building or to get in the street, is, it's a lottery.

NARRATOR: The earthquake was just the beginning.

It alone doesn't explain how Port Royal plunged into the sea.

It would sink for an entirely different reason.

Scientists call it liquefaction.

For the people of Port Royal, it was hell on earth.

The sandy ground where they'd built their houses turned into a deadly quagmire.

IAIN: So what happens with liquefaction is you've got sand with lots of water in it

and as you shake it, it turns into a slurry; it liquefies.

NARRATOR: Rarely captured on camera, this footage reveals the horrors of liquefaction at

work; in Niigata, Japan; on June 16th 1964.

The energy from a massive earthquake separated the grains of sediment below the

city, allowing water to rush to the surface; earth turned to quicksand,

sucking the city down.

The unlucky people of Port Royal wouldn't have known how solid land

can become liquid death.

Minutes into the earthquake, the second catastrophe unfolded, as the ground

sheered open; water and sand erupted from it.

The longer the ground shook, the more liquid the sand became.

Grand houses, churches, taverns and even Port Royal's forts sank like stones.

-Those houses, which back just now, appeared the fairest and loftiest in these parts, were

in a moment sunk down into the earth and nothing was to be seen of them.

NARRATOR: Some people were trapped, half in the sand and half out.

-The earth received up to their necks and then closed upon them, squeezing them to

death with their heads above ground.

Many of which the dogs eat.

NARRATOR: Many perished in this quicksand;

but there is one incredible story of survival.

A French Merchant, Lewis Galdy, found himself sucked into the ground.

JON: Everyone thought he was dead and then, in the succeeding shock, he was spat

out into the sea and he survived by swimming to the nearest boat; after which he

became a really religious man.

NARRATOR: In all, two thirds of Port Royal sank.

Taking with it 2,000 souls and hundreds of buildings.

It's reported that the city took only minutes to disappear into the sea.

But the chaos the earthquake had unleashed wasn't over.

lost city, we can reveal extraordinary evidence that

the earthquake delivered one last shock to Port Royal.

Embedded in the seafloor are the skeletal remains of a large ship.

She lies right amongst the ruins of a house on Lime Street.

-Well the clear question is, why is there a ship sitting on the floor of a

building in Port Royal?

NARRATOR: The strange discovery was excavated in the 1980s by Donny Hamilton.

Now Jon wants to find out exactly what it tells us about Port Royal's day of doom.

DONNY: What we see here is a planned view of building five and building four.

We came across a timber, which turned out to be the keel of a ship.

NARRATOR: But how could a ship, presumably in harbor, crash into a house in the

middle of town?

Would the identity of the stricken ship solve the mystery?

When Donny's team searched the records, they revealed a possible contender; an English

warship measuring 74 feet long.

Similar to this ship, she was called HMS Swan.

-We knew from the records that the Swan was in the harbor at the time of the

earthquake and it fits the basic dimensions of the ship that we found in building four.

NARRATOR: It turned out that, on the June 7th 1692, HMS Swan was being serviced at

Port Royals wharfs.

All clues point to one conclusion.

JON: You have a ship that would have been sitting in the harbor, a good 200 feet from

this building, has now been deposited, launched actually on top of it.

I mean, it's quite clearly evidence of a tsunami.

NARRATOR: The tsunami was the third cataclysm to hit Port Royal.

One eyewitness account tells of the sea retreating from Kingston Harbor, before the

wave hit.

It was a wave similar to the tsunamis that devastated Japan in 2011 and Thailand in 2004.

(screams).

The tsunami would explain what happened to HMS Swan.

Empty of ballast, HMS Swan was like a cork on the mighty wave that crashed over Port Royal.

She was hurled across the drowned city;

washed down Queen Street

finally crashing into a house on Lime Street.

Piercing its walls with considerable force.

The archaeologists have mapped the fate of Port Royal.

Port Royal was laid to waste by an earthquake, quicksand and tsunami waves.

The disaster left the city cut off from the mainland.

All that remained was a devastated island and thousands of dead bodies.

-A multitude of whose corpses floated a great many days after; from one side of the

harbor to the other.

Caused such an intolerable stench that the dead would like to destroy the living.

NARRATOR: When news of the disaster arrived in Europe,

it seemed that God had finally delivered his judgement on the wicked pirate city.

-When the news reaches the home country, there's quite a widespread feeling

that the wickedest city in the English speaking world had just got its just desserts.

-So it was seen as divine retribution; it was seen as just punishment for the loot

and terrible behavior that took place in Port Royal.

-By this terrible judgement, God will make them reform their lives; for there was not

a more un-Godly people on the face of the earth.

NARRATOR: Port Royal never recovered its former glory.

The trading jewel of the Caribbean was wiped off the face of the earth.

JON: It's interesting to think, if the earthquake hadn't actually struck here,

that this place could have developed somewhere like Manhattan, or somewhere like

Hong Kong.

NARRATOR: But in the end, it was Port Royal's lethal location, on an active fault

zone and deadly quicksand, that sealed its fate.

Half a world away, California, lies on one of the most

infamous fault zones in the world.

And right off shore, is an island that might just be the safest place, when the next

big one hits!

Alcatraz, The Rock.

Uncle Sam's Devil's island.

America's worst, Al Capone, Machine Gun Kelly

and Whitey Bulger, all called the "rock" home.

The island lies within sight of shore, but escape is almost impossible.

Prisoners who tried, were met with some of the Bay's most powerful forces.

The island of Alcatraz sits alone in the middle of San Francisco Bay...

Within this dramatic landscape, Alcatraz and the remnants of the renowned US

Federal prison are just over a mile from the heart of the city.

For 29 years, it held some of the most dangerous and notorious

criminals in history.

Officially, no one successfully escaped 'the rock'.

But why exactly was no inmate able to break out of Alcatraz?

Today, the Island is a museum run by the National Park Service.

Over a million people visit every year.

One man has watched it rise to become one of America's most visited attractions.

Ranger John Cantwell, he's worked on the Island for over 25 years.

JOHN: Where I'm standing is on Broadway, this is the main corridor in the cell house.

Alcatraz being a super max penitentiary meant that you had high security, one officer

for every three convicts.

They were constantly being watched.

12 times a day they would have counted every convict in this penitentiary building.

NARRATOR: But it's true strength as a prison can't be explained just by the

thickness of its walls.

Or the vigilance of its guards.

The waters around the rock were also a deadly barrier to escape.

Now science can explain just how and why the Bay was so dangerous.

NARRATOR: Draining the San Francisco Bay reveals Alcatraz as a pinnacle

of bedrock emerging from the seafloor.

It's surrounded by mountain peaks.

All of them are ancient survivors from an age of earthquakes.

Tom Parsons is a geophysicist with the United States Geological Survey.

He's studied this area for decades.

TOM: So we're standing at the Golden Gate and we're standing on mountains that were formed

a hundred million years ago.

Now we're sandwiched right between the San Andreas and the parallel Hayward Fault

both of which are helping to accommodate plate motion here between the Pacific and

North American plates.

NARRATOR: San Francisco sits right on the edge of the North American Plate.

As the Pacific Plate grinds north past it, stress builds up along the major fault lines

in the area, the Hayward Fault and most notably the San Andreas.

TOM: This region is very volatile it, it produces large earthquakes.

We've seen them in 1906, 1868, both were devastating earthquakes in San Francisco.

NARRATOR: The nightmarish effects of the 1906 earthquake, 7.9 on the Richter

scale, are a reminder of how the area's violent geology threatens the existence of a

great city.

Over 100 million years ago, the landscape here was entirely different.

There was a third plate between the two larger ones called the Farallon.

TOM: The Farallon Plate used to sit between the Pacific and North American Plates.

It was shoved underneath the North American plate over all that time.

NARRATOR: The movement of the Farallon Plate was the catalyst that created

San Francisco Bay and Alcatraz as it ground under the North American Plate.

This process is called subduction.

As the Farallon Plate disappeared, fragments of the Earth's crust were forced

upwards, creating a valley and mountains.

TOM: Alcatraz was part of the coast range belt that was uplifted by the subduction of

the Farallon Plate.

NARRATOR: The Bay area was then a long, forested valley with a number of

Rocky Mountains one of these mountains, was Alcatraz.

10,000 years ago as the last ice-age came to an end the area was deluged by billions

of gallons of melt water.

This created what we call San Francisco Bay.

Alcatraz became an island.

This 1853 photograph shows the tip of the drowned mountain as a featureless rock in the

middle of the Bay.

Alcatraz may look tranquil and isolated.

But it's surrounded by powerful natural forces.

What earned the island its deadly reputation, and what may have happened during

attempted escapes?

Over three decades there were 14 daring escape attempts from the island.

The story of one of these is legendary.

-Probably the most famous escape attempt would be the 1962 breakout.

NARRATOR: Frank Lee Morris, and brothers Charles and John Anglin devised an audacious

bid for freedom.

-The escape attempt was incredibly ingenious.

It involved stealing an immense amount of material, dozens of rubber raincoats,

glue, electric motors to turn into drills.

The guys even made a periscope, they made a flashlight.

NARRATOR: Now they had to use these homemade tools to breach the prison walls.

JOHN: We're in one of the Anglin Brothers cells and they were ingenious to actually

create a portal at the back of their cell.

And they fashioned a drill made out of a vacuum cleaner engine, put a diamond bit on

the end of this thing and then poked holes through the concrete to loosen up the

concrete around the air vent.

Dummy heads were made out of concrete material, human hair glued onto the heads and the

faces painted on these heads and at night with the lights down it looked like they were

sleeping in their cells.

So in the cell house, the lights go out at 9:30.

That's basically when they make their break.

Once the lights are out the heads are in place they go up to the rooftop and they've got

from 9:30 to 6:30 the next morning to make it to the mainland.

50 rubber raincoats glued together, Alcatraz escapees

Frank Lee Morris and the Anglin brothers made a makeshift raft and life vests.

It was their lifeline to freedom.

They carried everything to the roof and dragged it down to the water's edge.

JOHN: So this is the actual spot where they entered the water.

Frank Lee Morris and the Anglin Brothers came down this hillside.

They dragged their raft.

Inflated it at the seawall here, jumped in and took off into the night.

They searched the waters looking for these three men, and the raft or the men were

never found.

NARRATOR: The official FBI documents state the three men and their raft were most

likely swept out to sea.

Their bodies were never recovered.

But is this what really happened?

Were they lost at sea?

Or could they have made it to the mainland?

To understand the fate of the three escapees on their raft, scientists are studying the

geology of the bay itself.

Can the sea bed offer an answer?

First, Patrick Barnard from the United States Geological Survey explores the underwater

landscape at the mouth of San Francisco Bay.

He's hoping analysis of the seabed will explain the powerful currents that surge

around Alcatraz, making escape attempts so dangerous.

-Today we're going to be mapping from the Golden Gate Bridge west towards the

outer coast.

NARRATOR: The investigation begins under the most iconic location in San Francisco Bay.

Draining the water from under the Golden Gate Bridge reveals a huge gorge.

It's far deeper than the rest of the Bay.

Large enough to hide a 30 story building.

But what happens to the seabed when the multi-beam vessel heads west to the open ocean?

As the boat moves farther from the bridge, the water grows much shallower.

The sonar readings suggest a dramatic transformation in the seascape below.

PATRICK: The bottom is changing, we're seeing a lot more sediment

on the seafloor now.

NARRATOR: Draining the water reveals an incredible sight.

PATRICK: We're starting to see some very large sand waves here that are emerging from

the depths of the Golden Gate strait.

NARRATOR: These formations on the seabed are huge.

PATRICK: So the largest sand waves are about 200 meters long, 6 meters high,

the biggest ones 10 meters high or about 3 stories.

NARRATOR: And they're sitting just yards away from the harbor entrance.

PATRICK: They look like probably what the Sahara would look like if you were walking

through it.

NARRATOR: These giant sand waves are caused by the huge tidal rush through

the Golden Gate Strait.

The fast-moving water picks up sand and then dumps it as it slows down.

PATRICK: You have all this sand and gravel being carried along and forced through this

narrow opening and then as the opening widens further and further all this material gets

deposited in these bed forms.

NARRATOR: The drained landscape shows how the geology of the seabed shapes

the powerful tidal currents in San Francisco Bay.

First the deep gorge that funnels the water into a jet stream.

Moving west, beyond the Bridge we follow the seabed as it rises from over 300 feet deep

to just 130 feet.

The 'drain' shows how the racing current dumps thousands of tons of sand, creating

these giant sand waves up to 30 feet high.

But what does this underwater landscape have to do with escaping from Alcatraz?

These racing tides are what the inmates had to contend with when fleeing the rock.

Is it possible that Frank Morris and the Anglin brothers

got caught in these wicked currents?

The records from the 1962 FBI investigation show the tide charts on June 11th.

From 9 PM to 3 AM there was a strong outgoing tide.

Which peaked at exactly 11:46 PM.

So, when did the three escapees hit the water in their home-made raft?

MARTINI: From the moment lights out happened, which I think was 9:30, as soon as

they could've they would have gotten out of their cells, give it an hour, hour and a

half to have gotten everything that they needed to through that vent on the roof, across

the cell house, down the other side, hit the water.

I think that they started paddling as soon as they got to the water.

Let's say 11:00.

NARRATOR: The three convicts would have been in the water at peak tidal flow during an

ebbing, outgoing tide.

What were their chances if their flimsy raft made of raincoats broke up, leaving

them to swim in the powerful currents?

PATRICK: If you tried to escape off the north end of the island especially during

ebbing tide like they did in 1962 where the currents are extremely strong and moving

straight out to sea.

It would have been very difficult to swim out of that current within an hour and a

half you could have been at the open coast.

NARRATOR: So Morris and the Anglin brothers had to struggle with the fastest and

deadliest current flow in the bay.

What happened to them is one of the great Alcatraz mysteries.

h been wildly different rumors

about the men's fate.

Some claim to have seen the three men on the mainland.

But this conflicts with the official FBI report into the escape.

Which states that their objective was Angel Island!

A 2 mile paddle north of Alcatraz.

-They did what nobody else ever did, they got off the island with a head start

and, and were never seen again.

-The official Bureau of Prisons report on these three men in the raft is that the

raft took on water, the men were in the San Francisco Bay, they became hypothermic and

the currents took them out to the Pacific.

NARRATOR: But this was never proved.

And when the story broke around the world, there was excitement and intrigue.

MAN (over TV): It appears to be the first successful escape in the history of the

maximum-security prison.

NARRATOR: For weeks, the FBI searched the bay,

their goal was to find them, dead or alive.

MAN (over TV): The escape triggered the greatest man

hunt in San Francisco's history.

NARRATOR: Though they never discovered any trace of the bodies, the FBI did find

evidence of the escape.

MARTINI: They recovered two of the inflatable life vests.

They recovered two of the plywood paddles found floating in different

places in the bay.

Another one of the life vests was recovered outside the Golden Gate at a beach north

of the Golden Gate.

There was no lack of evidence that they escaped.

NARRATOR: Draining San Francisco Bay reveals how powerful currents on the

surface that swept men to their deaths are shaped by the contours below.

But for the three inmates, if they did reach the open ocean there was one more deadly

challenge because of its high population of great white sharks this area is known as

the Red Triangle.

PATRICK: In June of '62, it would have also been during up-welling season

like it is now.

So, you have lots of nutrients in the water column.

Lots of fish and lots of bigger predators, so it's likely there could have been

more great whites in the area than there are during the rest of the year.

NARRATOR: So if they made it this far out, dead or alive, they may have become prey for

the great whites.

The bodies of the three inmates were never found.

The infamous prison closed its doors in 1963 with a perfect record.

Officially there were no successful escapes from Alcatraz, though many tried.

JOHN: The conditions surrounding this island is what really made it an

escape-proof prison.

MARTINI: The bay was the most formidable of the prison's walls.

You could say that the bay has really created Alcatraz' reputation.

NARRATOR: The 'perfect prison' was the result of extraordinary geology.

Deep gorges, giant underwater sand dunes,

hard bedrock pillars at the Golden Gate Strait,

powerful currents and even great predators that roam the waters outside the Bay.

All natural phenomena that made the rock 'inescapable'.

But there is another mighty natural force at work in San Francisco Bay that dwarfs even

the power of the ocean currents.

A drained Pacific Ocean reveals the first clue.

Deep under the waters off the coast of San Francisco lies the infamous

San Andreas Fault.

The shifting tectonic plates have caused major earthquakes in the past.

The most deadly in 1906.

Over 3000 people lost their lives.

But could an even deadlier earthquake hit the area?

The so called 'big one'.

-So in our forecast we actually consider an earthquake that could start at

the southernmost part of the San Andreas Fault, run all the way along through the bay area

up north, involves the entire San Andreas Fault zone.

That earthquake would be on the scale of 8.2 to 8.4 in magnitude.

NARRATOR: The devastation would be far greater than the destruction caused

by the 1989 quake.

TOM: If we were to see an earthquake of that scale in San Francisco that would

cause, unfortunately a lot of casualties, many buildings would collapse, freeways and

infrastructure type things would be in danger.

If it did happen I think we would see significant destruction in the city and

throughout the bay area and throughout California.

NARRATOR: The massive earthquake could cause parts of the city to

topple into the sea.

Much of the downtown core destroyed.

The Golden Gate Bridge pushed to its engineering limits.

But when the fire and smoke clears, 'one' place will still be standing.

TOM: During a big earthquake Alcatraz would be a safe haven because it is built out of

very strong rock.

It's not going to collapse under strong shaking like soft soil would.

It's been there for 100 million years, it's hung in there, so it's going to do

well under an earthquake.

MARTINI: If the geologists are correct and when the San Andreas lets go Alcatraz is

the safest place to be, that is the ultimate irony.

The island that so many men wanted to get away from is the place

that's gonna offer the refuge.

NARRATOR: By draining Alcatraz and exposing the secrets hidden on the seabed, a

different picture of the island emerges.

The explanations behind its most legendary mysteries involve more than just the

prison itself.

The geography of San Francisco Bay, the waters, the rocks, the wind and the fog, a

tightly woven net making Alcatraz an inescapable place.

Unless the 'big one' hits.

Draining the waters around Port Royal and Alcatraz island reveal deep powerful

geological forces at work.

Captioned by Cotter Captioning Services.