Professor Danielle George uses five decades of BBC archive to find out how well disaster documentaries keep pace with scientific theories that advance every day.
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Natural disasters unleash forces
that are, literally, earth-shattering.
Whether it be an earthquake, a volcanic eruption, a tidal wave,
each is terrifying.
but fascinating too.
Hollywood disaster movies make for a thrilling spectacle,
but what about disaster documentaries?
Surely we look to them to provide answers, not just entertainment.
But to do that, programmes need to keep pace
with science that advances every day.
So, I've searched the archives
of the ground-breaking history series Timewatch
and 60 years of BBC documentaries,
to see how film-makers have dealt with disaster,
providing an extraordinary insight
into one of the fastest-moving branches of knowledge.
I'll see how rival theories keep emerging
on the destruction of ancient Atlantis...
It's normal, as a scientist that you guess, essentially,
what might have happened, say, in Atlantis,
based on the evidence at the time.
..how there's still much to learn
about history's most famous volcanic eruption at Pompeii...
Science, if it's healthy, is a constant state of doubt.
..how film-makers explore theories
that sometimes sound barely believable.
Was this killer wave of 400 years ago a British tsunami?
These films do show that historians and scientists have made
incredible advances in the study of historical disasters.
Best of all, we can share that thrill of discovery
and a new understanding of some of history's greatest calamities.
As an engineer, I'm fascinated to discover how things work.
But, as I've studied the film archive on disasters,
I've realised we're still learning how the Earth itself works.
The experts in this field keep turning up
fresh evidence and new theories.
What they thought was true just a few years ago
may no longer seem certain today.
But there's still something in me
that wants to ask what actually happened to cause such and such?
Was it X or was it Y? Surely somebody knows.
For me, searching the film archive offers
a unique opportunity to see how theories develop over time.
I know that definite answers will be hard to find.
For instance, this beach I'm on in south Wales was hit
by a giant wave 400 years ago, causing huge loss of life.
Some researchers say it was a massive storm surge.
Much more controversially, others believe it was a tsunami,
caused by an earthquake out at sea.
I'll come back to that later,
but it's just one example of how researchers,
and the film-makers who document their work,
are forever seeking new explanations
for some of the greatest calamities to ever strike our planet.
Since the dawn of time,
we humans have been trying to understand how the Earth works.
Specifically, the earthquakes and volcanic eruptions
which can wipe out whole cities in moments -
events so cataclysmic, they're still often simply called acts of God.
Before we consider the disasters themselves,
we need to look at the science behind them.
The realisation that the Earth has a constantly moving crust
is really very recent
and it's completely changed our understanding of disasters.
This has only really been an accepted theory
since as late as the 1960s.
Earthquake science is really quite novel and quite new
and the last 30 years or so have shown incredible developments.
And so, when this film appeared 45 years ago,
it was proclaiming nothing less than a revolution.
Nearly all earthquakes occur at the boundaries
between the great plates of the Earth's outer shell.
In the Middle East and the Mediterranean,
the home of many ancient civilisations,
there's an extraordinary jumble of large and small plates.
Dan McKenzie of Cambridge University
is one of the young revolutionaries of the Earth sciences.
He played a pioneering part in first telling
how the first great plates move as rigid units about the globe.
Most of the worst earthquakes in the Mediterranean occur
because Greece and Turkey are moving really quite rapidly westwards,
at about 5cm a year.
This means they've moved about 100 yards since the time of Socrates.
This pair of scissors and a bobbin show what's happening.
The bottom of the scissors is Africa and the top is Europe.
Bobbin is Turkey.
As Africa comes towards Europe, Turkey is squeezed out of the way.
In this village, three-quarters of the population perished.
An earthquake struck at 2.15 in the afternoon of 31st August, 1968.
It killed 10,000 villagers and some of the bodies were never found.
When the heavily-built roof of this communal wash house
fell on them, 28 women died.
The energy let loose in this earthquake was equivalent
to an H-bomb of several megatons.
The film shows how this new theory,
that pieces of the Earth's crust collide
and grind against each other,
allowed scientists to understand even very recent disasters
in a completely new way.
Right across the world, in California,
the San Fernando earthquake of 1971 awoke old faults
that hadn't moved for thousands of years.
It killed more than 60 people and gave warning
of what more severe earthquakes might do to Californian cities.
Earthquakes are part of a systematic remodelling of the Earth.
That's the doctrine of a new generation of Earth scientists,
like Tanya Atwater.
She worked out how movements of the ocean floor have affected the land
and so explain afresh much of the scenery of the western USA.
When I was in school, I was taught that the Earth makes its mountains
by a complicated sort of sinking and bobbing action,
first down and then up again.
That doesn't seem to be the case at all.
Most mountains seem to be made
by one piece of the Earth's outer crust
pushing sideways against another.
This is some of the damage from the recent San Fernando earthquake.
The buckling here is just the latest step
in the buckling of the Earth that made the mountains behind.
Here, great plates are grinding.
The coastal strip of California is edging
past the rest of North America.
This is three feet of mountain that was thrown up
in the recent earthquake, just like the sidewalk was.
It doesn't look like much, but you have to think about this happening
over and over again, maybe once a century for thousands of centuries.
If you look at the documentaries in the early '70s,
they were still explaining plate tectonics to the audience.
Now, if you look at more recent documentaries,
plate tectonics is very broadly understood by the viewing public,
I think, so they're starting from a different point.
Once you know how recently the nature of the Earth's crust
was still a mystery, it's easier to understand
how theories are still being revised and refined.
I'm going to look first at how this rapidly developing knowledge
actually posed problems for film-makers.
I've been looking at a series of films tackling the same subject,
with each of them drawing a different conclusion.
One of the most enduring, most romantic mysteries of all
is the search for the fabled island of Atlantis.
Historians have argued whether the story of a lost civilisation,
first told by the Greek philosopher Plato, around 350 BC,
has a basis in fact, or whether it's merely a legend.
Finally, in 1972,
archaeologists discovered startling new evidence
that Atlantis may have truly existed
but was wiped out in a natural disaster.
This is how Plato had described it.
"In this island of Atlantis,
"there was the fairest and noblest race of men that ever lived.
"But they fell from grace
"and were punished by the Earth shaker Poseidon.
"And afterwards, there occurred violent earthquakes
"and floods and, in one terrible day and night,
"the island of Atlantis disappeared in the depths of the sea."
The new evidence suggested
that the disaster struck in the eastern Mediterranean
on an island now crowded with tourists ever year,
but which, in 1972, was a sleepy backwater -
Santorini, sometimes known as Thera.
A land of grapes and wine,
one of the most enchanting of all the Greek islands of the Aegean,
a picturesque, idyllic island on the surface but, underneath,
there lurks a threat of terrible natural violence.
For Santorini is an area of alarming geological instability.
These cliffs are the walls of a caldera,
a vast crater that formed when the erupting volcano collapsed,
leaving a gaping hole to be filled by the sea.
It was a Greek philosopher, Plato,
who first wrote of the legend in the fourth century BC.
It told of an ancient island civilisation.
They became greedy and were punished by the gods
and their land sank beneath the sea.
What the archaeologists had just discovered was an entire city
buried beneath tonnes of volcanic ash.
And, remarkably, it seemed to match Plato's description
of a wealthy, civilised society,
with a taste for artistic expression.
Perhaps the most exciting discoveries are the frescos,
and we arrived at the site
just as completely new wall painting was being uncovered.
Skin divers and fishermen at work. One goes down with a hook.
One might be collecting sponges.
And, as the divers pick their way through the coral on the seabed,
on the surface, a convoy of ships is on the move,
led by a 50-oared galley.
What's more, the eruption on Santorini also appeared
to neatly solve another long-standing historical mystery.
Experts already knew that, at almost the same time,
sudden disaster had overcome the island of Crete,
60 miles to the south.
The wealthy and highly developed civilisation there,
the Minoan kingdom, disappeared almost overnight,
and for no obvious reason.
But, armed with their new knowledge of the Earth sciences,
archaeologists imagined that the volcano on Santorini
had sent out a tidal wave big enough
to cause wholesale destruction on Crete.
Tidal waves of appalling violence, perhaps some 600 feet high,
came raging in over the exposed northern coasts of Crete.
Buildings had been dragged to the ground, as the waves receded.
These waves had been created
by the collapse of the volcano in Santorini,
some 60 miles away to the north.
This was a ground-breaking piece of historical detective work.
Atlantis had been found and the mystery of the Minoans solved.
But in less than ten years, new evidence emerged,
forcing the very same team of film-makers
to backtrack on the tsunami theory.
On islands much closer than Crete, especially the island of Melos,
archaeologists found no evidence of a giant tidal wave.
We saw no evidence at all
of these great waves, tidal waves, tsunamis,
whatever you want to call them, in Melos.
If there were great tsunamis which were rushing across the ocean
and going to flatten the palaces of Crete,
we would have expected to find traces of that also in Melos.
I have the feeling, therefore,
that it wasn't as disastrous in the Aegean,
as a whole, as is sometimes thought.
But, if it wasn't a tsunami,
what then caused the destruction of the Minoan civilisation on Crete?
The film shows how archaeologists revisited all the clues,
just like detectives reopening an old case.
In particular, they looked again
at the wall paintings they'd uncovered
and now, built a theory that the Minoans were wiped out
by invaders from the Greek mainland.
It's a fascinating insight into the way that archaeologists
necessarily use one piece of a jigsaw to imagine the whole picture.
With the tidal wave theory crushed,
the chief archaeologist on Santorini had to come up with a new narrative
to explain those wall paintings of people in the sea.
He first interpreted the figures in the water
as underwater fishermen or sponge divers
but later, he recognised them to be dead bodies,
sinking to the bottom of the sea,
casualties of some kind of naval engagement
that seems to be taking place on the surface above them.
The figures in the water may yet turn out to be
evidence in favour of the invasion thesis.
In the space of less than ten years, one important theory had emerged,
been shot down and then replaced by another.
It's very easy to look back and say they got it all wrong,
but isn't this experimental approach
what archaeology, science too, is all about -
providing new answers to old questions
with evidence that's constantly emerging?
Science, if it's healthy, is a constant state of doubt.
There are phrases like, "Scientists believe that..." -
a phrase I hate because it doesn't represent
this constant disagreement that has to go on in science or else it dies.
And, of course, that wasn't the end of it.
Discovering Atlantis is pretty much the Holy Grail
for archaeologists and a perennial subject for TV documentaries.
In 2002, film-makers once again reported that it HAD been found.
But in a different part of Greece altogether.
A separate team of archaeologists, digging on the Greek mainland,
declared they'd found Atlantis...
..and that it had been destroyed by a quite different natural disaster.
This is the coast of Greece on the Corinthian Gulf,
150km west of Athens.
It is one of the most active earthquake regions in the world.
According to old Roman texts,
there was once a great Ancient Greek city here, called Helike.
2,500 years ago, Helike was a thriving metropolis.
Over 5,000 people lived and worked within its walls
and pilgrims thronged to its temple of Poseidon.
But on one cold winter's night, in 373 BC,
the god of earthquakes and the sea turned on his own people.
The ancient sources said the earthquake struck at night
when most people were caught in their houses.
A massive tidal wave or tsunami or sea wave came in...
..and swept away all survivors.
Helike and all of its people were swept to the bottom of the sea,
never to be seen again.
Just a few short years after the disaster,
the Greek writer Plato created the story of Atlantis.
The archaeologists had been toiling here for 15 years,
uncovering pottery and other artefacts,
when they came upon structures
which seemed to show signs of damage by tidal wave.
Finally, in the walls below them,
was possible evidence of the disaster itself.
There were signs some huge force had struck the building.
This wall has been knocked down toward the sea.
That has the kind of pattern that you see when you have the backwash
from the enormous wave going back to the sea...
..and knocking them down in the direction of the sea.
So, it seems that, after 15 long years of searching,
their team may have succeeded
where so many other archaeologists have failed.
They believe these walls are just the first glimpses
of the buildings that must lie in the ground around them.
Beyond them, towards the hills, should lie the rest of the city,
waiting to be uncovered.
Now it seems the city whose destruction inspired
the legend of Atlantis may finally have been found.
So, was that the end of the quest for Atlantis?
It's a mystery that just won't die.
When Timewatch joined the search for Atlantis a decade later,
the pendulum had swung right back to where it was in 1972.
Historian Bettany Hughes went hunting for fresh evidence,
homing in, once again, on the island of Santorini.
Atlantis hunting is a fraught exercise
but, precisely because it has generated so many wild theories,
there's even more reason to try to sift the fact from the fiction.
Fresh scientific evidence buttresses the idea that Plato's story
was inspired by a real island and a real ancient civilisation
that was destroyed by a real natural disaster...
..an eruption on a scale the ancient world had never experienced before.
This was an eruption that shook much of the planet.
Ash was transported as far north as the Black Sea,
as far east as central Turkey and as far south as the Nile Delta.
Global temperatures dipped, stunting plant growth, even in Ireland.
The early documentaries show a completely different picture
from the modern ones, due to this advancement of science.
New technologies, like satellite imagery, that we can now study,
that give us a better global picture of what's happening,
GPS, which records the relative movements on two sides of a fault
before, during, after an earthquake.
All of this instrumentation is providing us new data
with which to study these natural events.
For these film-makers, Santorini also seemed to fit perfectly
with the description which Plato had provided.
The first thing that strikes you is its really odd topography.
The land just juts straight out of the sea
and then you get these small islands, ringed by water,
which are then, in turn, cradled
by that massive semicircle of land up there.
Now, just listen to what Plato has to say about his Atlantis.
"There were circular belts of sea and land enclosing one another,
"some greater, some smaller."
Of course, that, in itself, doesn't prove anything.
There could be loads of locations all round the world
that match this description.
But, nonetheless, this account
and that landscape are really remarkably similar.
Bettany's team had revived the 1972 theory
that a massive tsunami had swept south from Santorini,
smashing into the island of Crete.
Evidence of the tsunami had now turned up on Crete itself.
Archaeologist Sandy MacGillivray and tsunami expert, Costas Synolakis,
are investigating the scale of the tsunamis
by mapping pumice on Crete's northern coastline.
Here's some. Here's a piece there.
That's so light, isn't it? Mm-hmm.
Cos it must have floated here, so... It's exactly what we like.
I mean, flotsam that comes out gives us an idea
of how high the wave reached.
So, the tsunami would have carried this up here to this headland.
At least to this point.
It could have carried it further up
and then it could have washed downriver
with the rain, with floods.
But this gives us, helps us bracket the size of the wave right offshore.
Costas has developed a computer simulation
of how the tsunamis would have travelled.
This is the initial wave.
We follow it all the way to Crete.
The first wave causes the shoreline to retreat, to move offshore.
We are less than an hour from the eruption
and the red on the south side of Crete
and the eastern Peloponnese are experiencing the big wave.
What do you think, Sandy, that says about what happened to Crete,
because most people live along the coast, don't they? I think so.
There was the city of Knossos which is inland
but, otherwise it's very much open coastline
and so, the death toll would have been staggering.
The hard evidence shows us
that here, there was a sophisticated trading civilisation
that flourished and was then swallowed by the sea,
ravaged by a disaster of legendary proportions.
Surely this is the root of Plato's Atlantis legend?
So, it's clear that theories come and go.
I suspect that's not the last we've heard of Atlantis.
Certainly, for the moment at least,
the evidence seems to favour Santorini
as the true location for Plato's Atlantis.
And it's brought home to me,
just how new much of the underlying science really is.
Tsunamis, in particular, are very poorly understood.
I don't think a lot of people realise
but, until the Indian Ocean tsunami, in 2004,
we didn't even know what a tsunami wave looked like.
It was only due to the complete chance of there being a vessel,
measuring the depth of water offshore of Thailand
when the tsunami passed under it, that we actually have a trace
of what a tsunami wave looks like, and that's 2004.
I'm going to look now at how film-makers have tried to keep pace
with another branch of the Earth sciences.
Just as with tsunamis, our understanding of volcanoes
has massively increased in the last 40 years.
In 1972, film-makers explored
some of the brand-new discoveries in volcanology.
A volcano in eruption is undoubtedly the finest pyrotechnic display
that man can ever see.
These falls are twice the height of Niagara.
And the fire fountain rises to almost 1,000 feet.
Volcanoes can be docile or violent.
In fact, volcanoes can vary enormously.
Some lava flows like water, some is thicker than treacle.
Volcanoes may have a far greater effect on the formation of the globe
than the volcanologists at first suspected.
Starting at the South Pacific,
volcanoes spread right through Indonesia
and up the island chain to Japan, Siberia and Alaska,
down the west coast of America, with a loop round the Caribbean,
though Mexico, Peru and Chile.
It's not a random distribution. There are patterns.
The structure of the Earth's crust is a series of rigid plates.
Volcanoes help determine the plate boundaries.
The film advances the then novel theory
that all the land we now live on
was at one time spewed from the mouth of an erupting volcano.
The best information which we have available at the present time
suggests that all the world's volcanoes, between them,
are currently producing about three cubic kilometres
of new material per year.
At this rate, sustained through the course of geological time,
the Earth's volcanoes would be capable of building up
the whole of the continental crust.
I think it's possible that the continental crust is, indeed,
due to four and a half thousand million years of volcanism.
This new understanding of volcanoes helped historians
to better explain huge historic disasters,
in particular the incredible story of Pompeii.
This city in southern Italy, along with its neighbouring Herculaneum,
was destroyed by a vast eruption of Mount Vesuvius in the year 79 AD.
The way that Pompeii citizens, who perished in the disaster,
seem frozen in time has captured our imaginations.
Their body outlines, preserved in the ashes,
give a real sense of their final moments.
More than 50 years ago, in 1966,
presenter Robert Erskine introduced
this remarkable story to the TV audience.
Thousands of the townsfolk died, poisonous by the sulphurous fumes,
in the basements of the houses and in the streets,
because they couldn't make up their minds what to do.
At the first cataclysmic explosion,
the mountain split, split open,
and it spewed its hideous innards all the way down this gulley,
straight towards the town.
Well, the inhabitants took one look and ran.
Down these very streets, they fled in terror,
away from the mountain, leaving everything behind them,
doors and houses open, the wine bars precipitantly deserted,
everything left where it was dropped in the terror of the moment.
A blind panic flight, it must have been.
By the early '70s,
our new understanding of Earth science would deepen this knowledge.
So, by 1974, film-makers could give
a much more detailed account of the disaster.
On Mount Vesuvius, broad sheets of fire
and leaping flames blazed at several points.
Ashes were already falling.
The buildings were now shaking with violent shocks.
Outside, on the other hand,
there was the danger of falling pumice stones.
We now know what actually happened.
A violent blast of gas shot a huge cloud of ash and pumice
miles into the air.
Down fell a rain of lapilli, pieces of pumice,
which buried the city to a depth of about ten feet.
Some people fled, but many who sheltered in the houses
were killed by buildings crumbling under the weight.
Others were trapped and died.
Survivors emerged into the open.
It was then that a hurricane of scorching ash
swept down the mountain.
Those in flight, their lungs seared by the red-hot lava particles,
collapsed in their tracks.
About 2,000 bodies have been found so far, one-tenth of the population.
The last minor eruption of Vesuvius was in 1944.
For 30 years, the volcano has been silent, dangerously silent.
But for how long?
Vesuvius today looks like a volcano.
Although you can climb to the top, no-one can be in much doubt
of the explosive forces not very far below the surface.
Vesuvius is a particularly dangerous volcano, capable of great violence.
Always the cities of the Bay of Naples must live in fear.
No-one can be sure when the mountain will split apart again.
And the learning process still continues,
fed by archaeology on one hand, volcanology on the other.
We have a particular volcanic eruption - Vesuvius, AD 79.
Our understanding of that is developing in two ways.
Firstly, more excavations are being done around Vesuvius.
But the other way is that we experience
other eruptions of similar types.
Therefore, you realise you can use the geophysical data,
the observational data, and so on,
of these different eruptions to understand AD 79.
It's clear how our understanding has increased
when you look at a much more recent film,
which adopted a rigorously forensic approach to the disaster.
In the early 1980s, a remarkable discovery was made
at Herculaneum, which lies only 7km from Vesuvius, closer than Pompeii.
300 skeletons were discovered, all victims of the volcanic eruption.
But, to work out exactly what killed them, scientists needed to study
another eruption that happened almost 2,000 years later.
The results appeared in a film, presented by Roman history scholar
and one-time Apprentice panellist Margaret Mountford.
What force was hot enough to reduce these poor people
to a pile of scorched bones?
We need to look at a volcano that erupted in North America
in the 1980s.
Mount St Helens National Park has
some of the most breathtaking scenery in the USA.
But on Sunday, May 18th, 1980, this peaceful world was transformed
when the Mount St Helens volcano erupted.
Volcanologists had seen eruptions before,
but this was the first time
they had managed to capture on film a little-known phenomenon.
The whole north face of Mount St Helens collapses.
As it does, it releases a searing-hot avalanche
of gas and dust that explodes down the sides of the mountain.
This is called a pyroclastic current.
The turbulent wave of gas measured 700 degrees Celsius
and travelled at nearly 500km an hour.
Can you explain what a pyroclastic current is?
A pyroclastic current is an avalanche
of searing-hot gas, ash and rock
that travels down the slopes of a volcano
at hundreds of kilometres an hour.
It's impossible to outrun and absolutely deadly.
When I think of an eruption, I think of streams of lava
coming down a mountain.
Well, the style of eruption - whether a volcano will erupt lava
or if it will erupt explosively -
is primarily a function of how much gas is in the magma.
If there is no gas in the magma,
then the magma will erupt as a lava flow or a lava dome.
And that is the actual magma,
the liquefied rock that's coming out as lava. Exactly.
And, in an explosive eruption,
the difference is the magma has gas bubbles
and as the gas in the magma makes its way to the surface,
the gas bubbles get bigger and bigger and bigger,
to the point where, when the volcano erupts,
the gases expand very quickly
and it rips the magma apart into very tiny pieces,
which are your ash and your pumice.
From what scientists witnessed at Mount St Helens,
and data gathered from other volcanic eruptions,
it's now possible to piece together
exactly what happened when Vesuvius erupted.
12 hours after the initial eruption,
the column above Vesuvius stretched nearly 32km high.
But under its own weight, it collapsed.
A pyroclastic current surged down the sides of the volcano
at speeds up 300km an hour.
Temperatures inside the explosive blast were over 500 degrees Celsius.
The wave of searing-hot gas and ash took less than five minutes
to strike Herculaneum 7km away.
The intense heat surge killed them instantly.
It vaporised their flesh.
And that is why all that remained
were blackened skeletons and cracked skulls.
This new insight into volcanoes gives historians a toolkit
with which to investigate previously unexplained events from the past.
We get new data all the time.
We didn't have a concept of the pyroclastic flow
and what pyroclastic flows did to people.
So, this constant drawing of information from other areas,
and comparisons and analogies,
means that the science is changing all the time.
The depth of knowledge which now exists
about the Vesuvius eruption shows
that with historians, scientists and film-makers working together,
it is possible to take an old mystery
and supply a definitive answer.
Bur my trawl through the film archive shows there are still areas
where that's not at all true.
One of the deadliest disasters ever to strike the planet
still has no known cause.
Or at least no cause which experts can agree on.
It was an epidemic which killed tens of millions of people
and could, some experts fear, reappear today.
650 years ago, the so-called Black Death
is thought to have wiped out
something close to a third of Europe's population.
But, as Timewatch reported in 1984,
the epidemic raises maybe the biggest question in medical history.
The cause of that holocaust, historians believe, was plague -
more specifically, bubonic and pneumonic plague.
New biological research, however, is coming to a different conclusion.
The time-honoured theory was that bubonic plague had been spread
by black rats.
The fleas that live on the rats, but also feed on humans,
were thought to be the way the disease was transmitted.
But did this theory add up, in the light of new evidence?
The Black Death first arrived in Britain on the Dorset coast.
By the end of 1348, it had most of southern England in its grip.
Six months later, it had spread through Wales,
the Midlands and East Anglia.
By the end of 1349, it had reached the Scottish Highlands
and the North of Ireland.
It moved across the country at about a mile a day
or even a little more than that, depending whose account you follow.
Now, this just doesn't fit in with what we know of plague today.
The winter of 1348 to '49 was unusually cold.
But bubonic plague does not appear to thrive in low temperatures.
The black rat is an animal
that likes the warmth.
It comes from India, basically, in that region.
The flea is very temperature dependent.
It only breeds when the temperature gets
between 65 and 85 degrees Fahrenheit and when the humidity is right.
According to Dr Twigg, there just weren't enough rats and fleas
to spread bubonic plague across Britain so rapidly
and with such fearful loss of life.
But if it wasn't bubonic plague, what was it?
One disease that fits the bill rather well would be anthrax.
Unlike bubonic plague, it can spread from person to person.
It's found, to a great extent,
in domesticated animals - cattle and sheep.
But, in a human being, when the spore gets into the body,
The body oozes dark blood from all the bodily orifices.
The fact that anthrax, rather than bubonic plague,
might have been the culprit shows, perhaps,
how little we really know about this huge episode in history...
..and how difficult it is for film-makers
to offer a definitive account,
with research constantly being updated.
When Timewatch returned to the question in 2004,
yet another possible candidate
for the killer disease had entered the frame.
The biologist is convinced he's found the answer
to the mystery of the Black Death.
Historians have spent a lot of time
interpreting what went on,
in terms of rats and fleas, which is incorrect
and I think we need the record straightened out.
Professor Duncan's analysis is controversial
but he's willing to speculate on the actual identity of the killer
which terrorised Europe for over 300 years.
His guess is based on symptoms
mentioned in some of the 14th-century accounts.
"Sudden fever, spitting blood and saliva
"and no-one who spat blood survived it."
"Brought on by an affliction of the head of vomiting blood."
"The accompanying putrefaction of humours
"caused the victim to cough up blood."
Could these be medieval descriptions
of someone dying of internal haemorrhaging?
From the symptoms, it has got features in common with Ebola.
Ebola is one of the deadliest diseases on Earth.
It's caused by a tiny threadlike virus,
which was first isolated 30 years ago in Africa.
It causes a wide range of symptoms - fever, coughing up blood
and, occasionally, lumps under the skin.
The tragedy that was played out across medieval Europe
no longer seems to be easily explained
as an epidemic of bubonic plague, spread by fleas.
We are in the uneasy position of not knowing the cause
of the most deadly epidemic ever to strike humanity.
And until we know, we can't be sure we could stop it happening again.
So, now two possible new diagnoses.
One of this country's leading authorities on epidemics
believes the Black Death could even have been a series of diseases,
striking around the same time.
I don't place all that much reliance on anyone, myself included,
coming up and saying, "This is the answer.
"It's not the plague bacillus, it's the anthrax bacillus
"or it's Ebola, or it's this or it's that or it's something else."
It's bad enough to get things diagnosed today, and I mean today.
Imagine what it's like 800 years ago.
I suspect, myself, there were deaths of all kinds of things,
all kinds of things,
and it's too easy to throw them all into the bubonic plague pot.
That's why I'm sceptical about it.
It would be wrong to be too harsh about these conflicting diagnoses.
After all, the second opinion is a long-established tradition.
But it does serve as a warning
about looking for certainty where it simply may not exist.
After studying these films, I think one of the reasons
why disaster documentaries are so fascinating
is that they make you wonder, "Am I safe? Could it ever happen here?"
Could a lovely beach like this, Dunraven Bay in south Wales,
really be the location for a huge natural disaster?
Timewatch revealed that's not as farfetched as it sounds.
400 years ago, the entire coastline of the Bristol Channel
was engulfed by an enormous flood.
The question is, what caused it?
On 20th January, 1607, a wall of water up to ten metres high
rushed over the low-lying sea defences.
Travelling at 30mph, the killer wave bore down
on the villages of Somerset and Monmouthshire.
It came without warning and left 2,000 dead in its wake.
Yet, for centuries,
this apocalyptic flood has been forgotten,
and only now are scientists piecing together the evidence left behind.
Was it just a huge storm
or was the killer wave of 1607 in fact a British tsunami?
It was a very timely question when this film appeared in 2005.
The terrible Boxing Day tsunami off Indonesia,
with a quarter of a million people dead,
was still fresh in everyone's mind.
The film looks at new research,
suggesting the flood had many of the characteristics of a tsunami,
in particular, the way the rocks are laid out on this beach.
At Dunraven Bay in south Wales,
hundreds of boulders lie at the foot of the cliffs.
Some have obviously just dropped off the face,
but others are less easy to explain.
This particular boulder, I'm pretty sure,
has been moved off the beach.
It's got some fossils in it which you don't normally associate
with the older limestones
which you find on the cliffs here.
So, it looks like this quite big boulder
has come from over there on the beach.
The force of water needed to move seven-tonne boulders
could easily be produced by a tsunami.
The way the boulders are lying gives Simon another clue.
That's 270 degrees west.
Certainly storms can move the odd boulder
and can fling boulders up onto the top of cliffs
but, given that we've got so many boulders in a train,
what we call a boulder train,
and they're all pointing back in the same direction,
that suggests to us a constant flow over time.
It would only have taken a five-metre tsunami wave
to shift these boulders.
For a storm to do the same thing, they calculate it would have taken
a wave at least 20 metres high, over 60 feet.
Yet the very idea of a tsunami laying waste to the Bristol Channel
goes against every assumption we have
about Britain being geologically safe.
The big surprise is that the seabed off the southwest tip of Ireland
is the location of an ancient but massive faultline.
On 8th February, 1980, sensors recorded an earthquake
from exactly this area, 4.5 on the Richter scale,
violent enough to give fresh impetus to the tsunami theory.
I think I've got the dark layer here.
I really like that style of film-making.
I think that's quite a change
from something of the 1970s,
the way that the evidence is presented.
Quite thin here. It's coming to about ten centimetres.
The dilemma scientists actually have themselves about the evidence
which, of course, has a great deal of uncertainty about it.
The film-makers are careful to say that much more evidence is needed
before the theory is widely accepted.
But the thought of an undersea earthquake zone,
just a short distance off the British coast,
is an intriguing hypothesis and a scary one, too.
The last film I'm going to look at is especially chilling
because it assembles compelling evidence
for disaster that's yet to happen.
This is the story
of how the greatest natural disaster
in human history might one day unfold.
The biggest wave ever seen...
..threatening death and devastation
on an unprecedented scale.
The power of this film lies in the fact
that it's based on a genuine scientific hypothesis,
yet it uses all the visual tricks
of the classic disaster movie.
The film reports a study of a volcano in the Canary Islands.
Some scientists fear that an eruption
would cause the volcano to crumble, producing a huge landslide.
That, in turn,
could displace enough water to trigger a mega tsunami.
The film goes on to imagine the terrible consequences
if a disaster like that happened for real.
Travelling at up to 800 millions an hour,
the giant wave surges out in all directions.
Immediately in its path,
the highly populated island of Tenerife.
Locals and holiday-makers alike
do all they can to outrun it.
the wave has claimed its first victims.
I don't think there's any doubt
that the initial wave will be
very catastrophic for the islands themselves.
So you're talking about thousands of people dead
and destruction on a scale that we've never seen
in this part of the world before.
Our mega tsunami's journey of destruction
has only just begun.
Over the following hours,
these waves will devastate the coastlines of Europe.
The emergency services have just three hours
before the wave strikes Britain.
The Environment Agency issues flood warnings
to the south coast
and rescue units are put on standby.
Police clear the streets of southern coastal towns,
evacuating schools and vulnerable communities.
A giant tsunami is spreading
throughout the Atlantic Basin.
Scientists estimate that the wave is travelling
at approximately 500mph.
Just three hours after the first UK warnings,
a wave up to 25 metres high
makes its first landfall in Britain...
From Cornwall, the wave surges
through the English Channel,
engulfing much of Britain's south coast.
In our scenario, London, our capital,
tucked in from the North Sea, is safely sheltered.
Models differ on what the wave might do
to our southern cities, as it works its way east.
Towns such as Brighton would suffer serious disruption.
We can get some idea of the impact
of a seven to ten-metre wave on the UK south coast,
by looking at what happened in the Indian Ocean in 2004
in places like Sri Lanka and Thailand.
The death toll was in the tens of thousands.
The population on the south coast of the UK
is probably quite a bit higher,
so that sort of wave would be immensely destructive in the UK.
But the greatest carnage would be inflicted
on the USA, with east coast cities like New York,
directly in the path of the tsunami.
New York, Boston, Washington, Miami.
Entire cities have been destroyed.
The number of casualties
is really hard to get at in something like this.
For the 25-metre scenario,
with maybe three to four hours' warning,
we came up with roughly 4.5 million causalities.
Around the world, there may be
one of these enormous events
maybe once every 20,000 years, maybe only once every 50,000 years.
We can't say when the collapse is going to occur.
It seems to already be close to failure.
So, the crucial question is not a matter of if, but of when.
If the worst were to happen, then at least WE'D have some warning,
unlike the people of Pompeii or maybe Atlantis,
who were suddenly overwhelmed
by forces they could only ascribe to the angry gods.
Given that we've only just begun to understand
what's happening beneath the Earth's surface in the past few decades,
it's little wonder that they looked for supernatural explanation
more than 3,000 years ago.
My trawl through the film archive clearly shows
that we've learnt a huge amount about natural disasters
in the last half-century,
and we've learnt so fast that it's hard for film-makers to keep up.
It's our scientific responsibility to be very humble
about the limitations of this knowledge
and what it's based on, but also invite debate.
It's important that new discoveries, that new theories are debated.
There has to be an acknowledgement that science changes.
As a scientist, I treat these films as a snapshot
that captures our understanding at a certain point in time.
These documentaries, whatever their imperfections, their flaws
and their distortions and all the complaints, you know,
"Things aren't being represented, it's not certain science,"
but it's describing possibilities,
and it's possibilities the knowledge of which may save lives.
As these films evolve, it's like actually being an observer
during the discovery process and I'm all in favour of that.
As the years go by, we understand more and more,
so I don't think we've seen the last documentary
on what happened 3,000 years ago in Atlantis, or Pompeii or even here.
Are you good? You all right?
Pleased to be back.
Your baby has been loved by me very much.
I'd like to say thank you.
I like you.
We have a report there's a suitcase washed up.
There's black human hair coming from the inside.
From earthquakes to tsunamis to volcanic eruptions, natural disasters are both terrifying and fascinating - providing endless fresh material for documentary makers. But how well do disaster documentaries keep pace with the scientific theories that advance every day? To try and answer that question, Professor Danielle George is plunging into five decades of BBC archive. What she uncovers provides an extraordinary insight into one of the fastest moving branches of knowledge. From the legendary loss of Atlantis to the eruption that destroyed Pompeii, Danielle reveals how film-makers have changed their approach again and again in the light of new scientific theories. While we rarely associate Britain with major natural disaster, at the end of the programme Danielle brings us close to home, exploring programmes which suggest that 400 years ago Britain was hit by a tidal wave that killed hundreds of people, and that an even bigger tsunami could threaten us again.