0:00:03 > 0:00:06Natural disasters unleash forces
0:00:06 > 0:00:09that are, literally, earth-shattering.
0:00:09 > 0:00:13Whether it be an earthquake, a volcanic eruption, a tidal wave,
0:00:13 > 0:00:16each is terrifying.
0:00:16 > 0:00:18but fascinating too.
0:00:20 > 0:00:24Hollywood disaster movies make for a thrilling spectacle,
0:00:24 > 0:00:27but what about disaster documentaries?
0:00:27 > 0:00:31Surely we look to them to provide answers, not just entertainment.
0:00:31 > 0:00:35But to do that, programmes need to keep pace
0:00:35 > 0:00:38with science that advances every day.
0:00:39 > 0:00:41So, I've searched the archives
0:00:41 > 0:00:44of the ground-breaking history series Timewatch
0:00:44 > 0:00:46and 60 years of BBC documentaries,
0:00:46 > 0:00:49to see how film-makers have dealt with disaster,
0:00:49 > 0:00:52providing an extraordinary insight
0:00:52 > 0:00:56into one of the fastest-moving branches of knowledge.
0:00:56 > 0:01:00I'll see how rival theories keep emerging
0:01:00 > 0:01:03on the destruction of ancient Atlantis...
0:01:03 > 0:01:06It's normal, as a scientist that you guess, essentially,
0:01:06 > 0:01:08what might have happened, say, in Atlantis,
0:01:08 > 0:01:10based on the evidence at the time.
0:01:10 > 0:01:12..how there's still much to learn
0:01:12 > 0:01:17about history's most famous volcanic eruption at Pompeii...
0:01:17 > 0:01:21Science, if it's healthy, is a constant state of doubt.
0:01:21 > 0:01:25..how film-makers explore theories
0:01:25 > 0:01:28that sometimes sound barely believable.
0:01:32 > 0:01:36Was this killer wave of 400 years ago a British tsunami?
0:01:39 > 0:01:43These films do show that historians and scientists have made
0:01:43 > 0:01:47incredible advances in the study of historical disasters.
0:01:47 > 0:01:51Best of all, we can share that thrill of discovery
0:01:51 > 0:01:55and a new understanding of some of history's greatest calamities.
0:02:13 > 0:02:19As an engineer, I'm fascinated to discover how things work.
0:02:19 > 0:02:22But, as I've studied the film archive on disasters,
0:02:22 > 0:02:26I've realised we're still learning how the Earth itself works.
0:02:29 > 0:02:31The experts in this field keep turning up
0:02:31 > 0:02:34fresh evidence and new theories.
0:02:35 > 0:02:38What they thought was true just a few years ago
0:02:38 > 0:02:40may no longer seem certain today.
0:02:43 > 0:02:45But there's still something in me
0:02:45 > 0:02:50that wants to ask what actually happened to cause such and such?
0:02:50 > 0:02:53Was it X or was it Y? Surely somebody knows.
0:02:59 > 0:03:02For me, searching the film archive offers
0:03:02 > 0:03:06a unique opportunity to see how theories develop over time.
0:03:09 > 0:03:12I know that definite answers will be hard to find.
0:03:13 > 0:03:17For instance, this beach I'm on in south Wales was hit
0:03:17 > 0:03:22by a giant wave 400 years ago, causing huge loss of life.
0:03:24 > 0:03:28Some researchers say it was a massive storm surge.
0:03:28 > 0:03:32Much more controversially, others believe it was a tsunami,
0:03:32 > 0:03:35caused by an earthquake out at sea.
0:03:35 > 0:03:37I'll come back to that later,
0:03:37 > 0:03:40but it's just one example of how researchers,
0:03:40 > 0:03:42and the film-makers who document their work,
0:03:42 > 0:03:45are forever seeking new explanations
0:03:45 > 0:03:48for some of the greatest calamities to ever strike our planet.
0:03:49 > 0:03:51Since the dawn of time,
0:03:51 > 0:03:55we humans have been trying to understand how the Earth works.
0:03:57 > 0:04:01Specifically, the earthquakes and volcanic eruptions
0:04:01 > 0:04:05which can wipe out whole cities in moments -
0:04:05 > 0:04:11events so cataclysmic, they're still often simply called acts of God.
0:04:13 > 0:04:15Before we consider the disasters themselves,
0:04:15 > 0:04:18we need to look at the science behind them.
0:04:20 > 0:04:24The realisation that the Earth has a constantly moving crust
0:04:24 > 0:04:26is really very recent
0:04:26 > 0:04:30and it's completely changed our understanding of disasters.
0:04:30 > 0:04:32This has only really been an accepted theory
0:04:32 > 0:04:35since as late as the 1960s.
0:04:35 > 0:04:39Earthquake science is really quite novel and quite new
0:04:39 > 0:04:42and the last 30 years or so have shown incredible developments.
0:04:43 > 0:04:46And so, when this film appeared 45 years ago,
0:04:46 > 0:04:50it was proclaiming nothing less than a revolution.
0:04:51 > 0:04:54Nearly all earthquakes occur at the boundaries
0:04:54 > 0:04:56between the great plates of the Earth's outer shell.
0:04:56 > 0:05:01In the Middle East and the Mediterranean,
0:05:01 > 0:05:03the home of many ancient civilisations,
0:05:03 > 0:05:06there's an extraordinary jumble of large and small plates.
0:05:08 > 0:05:10Dan McKenzie of Cambridge University
0:05:10 > 0:05:14is one of the young revolutionaries of the Earth sciences.
0:05:14 > 0:05:16He played a pioneering part in first telling
0:05:16 > 0:05:20how the first great plates move as rigid units about the globe.
0:05:20 > 0:05:24Most of the worst earthquakes in the Mediterranean occur
0:05:24 > 0:05:28because Greece and Turkey are moving really quite rapidly westwards,
0:05:28 > 0:05:30at about 5cm a year.
0:05:30 > 0:05:34This means they've moved about 100 yards since the time of Socrates.
0:05:35 > 0:05:38This pair of scissors and a bobbin show what's happening.
0:05:38 > 0:05:42The bottom of the scissors is Africa and the top is Europe.
0:05:42 > 0:05:44Bobbin is Turkey.
0:05:44 > 0:05:49As Africa comes towards Europe, Turkey is squeezed out of the way.
0:05:52 > 0:05:55In this village, three-quarters of the population perished.
0:05:55 > 0:06:01An earthquake struck at 2.15 in the afternoon of 31st August, 1968.
0:06:01 > 0:06:06It killed 10,000 villagers and some of the bodies were never found.
0:06:06 > 0:06:10When the heavily-built roof of this communal wash house
0:06:10 > 0:06:12fell on them, 28 women died.
0:06:13 > 0:06:16The energy let loose in this earthquake was equivalent
0:06:16 > 0:06:19to an H-bomb of several megatons.
0:06:20 > 0:06:22The film shows how this new theory,
0:06:22 > 0:06:25that pieces of the Earth's crust collide
0:06:25 > 0:06:26and grind against each other,
0:06:26 > 0:06:30allowed scientists to understand even very recent disasters
0:06:30 > 0:06:32in a completely new way.
0:06:33 > 0:06:35Right across the world, in California,
0:06:35 > 0:06:39the San Fernando earthquake of 1971 awoke old faults
0:06:39 > 0:06:42that hadn't moved for thousands of years.
0:06:42 > 0:06:45It killed more than 60 people and gave warning
0:06:45 > 0:06:49of what more severe earthquakes might do to Californian cities.
0:06:50 > 0:06:54Earthquakes are part of a systematic remodelling of the Earth.
0:06:54 > 0:06:57That's the doctrine of a new generation of Earth scientists,
0:06:57 > 0:06:58like Tanya Atwater.
0:06:58 > 0:07:02She worked out how movements of the ocean floor have affected the land
0:07:02 > 0:07:05and so explain afresh much of the scenery of the western USA.
0:07:05 > 0:07:09When I was in school, I was taught that the Earth makes its mountains
0:07:09 > 0:07:12by a complicated sort of sinking and bobbing action,
0:07:12 > 0:07:14first down and then up again.
0:07:14 > 0:07:16That doesn't seem to be the case at all.
0:07:16 > 0:07:18Most mountains seem to be made
0:07:18 > 0:07:21by one piece of the Earth's outer crust
0:07:21 > 0:07:22pushing sideways against another.
0:07:22 > 0:07:26This is some of the damage from the recent San Fernando earthquake.
0:07:26 > 0:07:29The buckling here is just the latest step
0:07:29 > 0:07:31in the buckling of the Earth that made the mountains behind.
0:07:33 > 0:07:35Here, great plates are grinding.
0:07:36 > 0:07:38The coastal strip of California is edging
0:07:38 > 0:07:40past the rest of North America.
0:07:42 > 0:07:44This is three feet of mountain that was thrown up
0:07:44 > 0:07:47in the recent earthquake, just like the sidewalk was.
0:07:47 > 0:07:51It doesn't look like much, but you have to think about this happening
0:07:51 > 0:07:55over and over again, maybe once a century for thousands of centuries.
0:07:58 > 0:08:01If you look at the documentaries in the early '70s,
0:08:01 > 0:08:05they were still explaining plate tectonics to the audience.
0:08:08 > 0:08:11Now, if you look at more recent documentaries,
0:08:11 > 0:08:15plate tectonics is very broadly understood by the viewing public,
0:08:15 > 0:08:18I think, so they're starting from a different point.
0:08:24 > 0:08:27Once you know how recently the nature of the Earth's crust
0:08:27 > 0:08:30was still a mystery, it's easier to understand
0:08:30 > 0:08:33how theories are still being revised and refined.
0:08:35 > 0:08:38I'm going to look first at how this rapidly developing knowledge
0:08:38 > 0:08:41actually posed problems for film-makers.
0:08:41 > 0:08:45I've been looking at a series of films tackling the same subject,
0:08:45 > 0:08:48with each of them drawing a different conclusion.
0:08:52 > 0:08:56One of the most enduring, most romantic mysteries of all
0:08:56 > 0:09:00is the search for the fabled island of Atlantis.
0:09:01 > 0:09:05Historians have argued whether the story of a lost civilisation,
0:09:05 > 0:09:09first told by the Greek philosopher Plato, around 350 BC,
0:09:09 > 0:09:14has a basis in fact, or whether it's merely a legend.
0:09:16 > 0:09:18Finally, in 1972,
0:09:18 > 0:09:21archaeologists discovered startling new evidence
0:09:21 > 0:09:24that Atlantis may have truly existed
0:09:24 > 0:09:27but was wiped out in a natural disaster.
0:09:27 > 0:09:30This is how Plato had described it.
0:09:31 > 0:09:33"In this island of Atlantis,
0:09:33 > 0:09:36"there was the fairest and noblest race of men that ever lived.
0:09:36 > 0:09:37"But they fell from grace
0:09:37 > 0:09:40"and were punished by the Earth shaker Poseidon.
0:09:45 > 0:09:48"And afterwards, there occurred violent earthquakes
0:09:48 > 0:09:50"and floods and, in one terrible day and night,
0:09:50 > 0:09:54"the island of Atlantis disappeared in the depths of the sea."
0:10:03 > 0:10:05The new evidence suggested
0:10:05 > 0:10:08that the disaster struck in the eastern Mediterranean
0:10:08 > 0:10:11on an island now crowded with tourists ever year,
0:10:11 > 0:10:15but which, in 1972, was a sleepy backwater -
0:10:15 > 0:10:19Santorini, sometimes known as Thera.
0:10:23 > 0:10:24A land of grapes and wine,
0:10:24 > 0:10:28one of the most enchanting of all the Greek islands of the Aegean,
0:10:28 > 0:10:32a picturesque, idyllic island on the surface but, underneath,
0:10:32 > 0:10:35there lurks a threat of terrible natural violence.
0:10:35 > 0:10:39For Santorini is an area of alarming geological instability.
0:10:41 > 0:10:43These cliffs are the walls of a caldera,
0:10:43 > 0:10:47a vast crater that formed when the erupting volcano collapsed,
0:10:47 > 0:10:49leaving a gaping hole to be filled by the sea.
0:10:51 > 0:10:53It was a Greek philosopher, Plato,
0:10:53 > 0:10:56who first wrote of the legend in the fourth century BC.
0:10:56 > 0:10:59It told of an ancient island civilisation.
0:10:59 > 0:11:03They became greedy and were punished by the gods
0:11:03 > 0:11:05and their land sank beneath the sea.
0:11:09 > 0:11:13What the archaeologists had just discovered was an entire city
0:11:13 > 0:11:16buried beneath tonnes of volcanic ash.
0:11:17 > 0:11:20And, remarkably, it seemed to match Plato's description
0:11:20 > 0:11:23of a wealthy, civilised society,
0:11:23 > 0:11:26with a taste for artistic expression.
0:11:28 > 0:11:31Perhaps the most exciting discoveries are the frescos,
0:11:31 > 0:11:33and we arrived at the site
0:11:33 > 0:11:36just as completely new wall painting was being uncovered.
0:11:38 > 0:11:44Skin divers and fishermen at work. One goes down with a hook.
0:11:44 > 0:11:46One might be collecting sponges.
0:11:48 > 0:11:51And, as the divers pick their way through the coral on the seabed,
0:11:51 > 0:11:55on the surface, a convoy of ships is on the move,
0:11:55 > 0:11:57led by a 50-oared galley.
0:12:01 > 0:12:04What's more, the eruption on Santorini also appeared
0:12:04 > 0:12:08to neatly solve another long-standing historical mystery.
0:12:11 > 0:12:15Experts already knew that, at almost the same time,
0:12:15 > 0:12:18sudden disaster had overcome the island of Crete,
0:12:18 > 0:12:2060 miles to the south.
0:12:20 > 0:12:24The wealthy and highly developed civilisation there,
0:12:24 > 0:12:27the Minoan kingdom, disappeared almost overnight,
0:12:27 > 0:12:29and for no obvious reason.
0:12:31 > 0:12:34But, armed with their new knowledge of the Earth sciences,
0:12:34 > 0:12:38archaeologists imagined that the volcano on Santorini
0:12:38 > 0:12:41had sent out a tidal wave big enough
0:12:41 > 0:12:44to cause wholesale destruction on Crete.
0:12:44 > 0:12:49Tidal waves of appalling violence, perhaps some 600 feet high,
0:12:49 > 0:12:53came raging in over the exposed northern coasts of Crete.
0:12:54 > 0:12:57Buildings had been dragged to the ground, as the waves receded.
0:12:57 > 0:12:59These waves had been created
0:12:59 > 0:13:02by the collapse of the volcano in Santorini,
0:13:02 > 0:13:04some 60 miles away to the north.
0:13:05 > 0:13:09This was a ground-breaking piece of historical detective work.
0:13:09 > 0:13:14Atlantis had been found and the mystery of the Minoans solved.
0:13:14 > 0:13:16Case closed.
0:13:17 > 0:13:20But in less than ten years, new evidence emerged,
0:13:20 > 0:13:23forcing the very same team of film-makers
0:13:23 > 0:13:25to backtrack on the tsunami theory.
0:13:27 > 0:13:32On islands much closer than Crete, especially the island of Melos,
0:13:32 > 0:13:36archaeologists found no evidence of a giant tidal wave.
0:13:38 > 0:13:40We saw no evidence at all
0:13:40 > 0:13:42of these great waves, tidal waves, tsunamis,
0:13:42 > 0:13:45whatever you want to call them, in Melos.
0:13:46 > 0:13:49If there were great tsunamis which were rushing across the ocean
0:13:49 > 0:13:52and going to flatten the palaces of Crete,
0:13:52 > 0:13:55we would have expected to find traces of that also in Melos.
0:13:57 > 0:13:59I have the feeling, therefore,
0:13:59 > 0:14:01that it wasn't as disastrous in the Aegean,
0:14:01 > 0:14:03as a whole, as is sometimes thought.
0:14:06 > 0:14:08But, if it wasn't a tsunami,
0:14:08 > 0:14:11what then caused the destruction of the Minoan civilisation on Crete?
0:14:15 > 0:14:20The film shows how archaeologists revisited all the clues,
0:14:20 > 0:14:23just like detectives reopening an old case.
0:14:24 > 0:14:26In particular, they looked again
0:14:26 > 0:14:28at the wall paintings they'd uncovered
0:14:28 > 0:14:32and now, built a theory that the Minoans were wiped out
0:14:32 > 0:14:35by invaders from the Greek mainland.
0:14:35 > 0:14:38It's a fascinating insight into the way that archaeologists
0:14:38 > 0:14:43necessarily use one piece of a jigsaw to imagine the whole picture.
0:14:43 > 0:14:46With the tidal wave theory crushed,
0:14:46 > 0:14:50the chief archaeologist on Santorini had to come up with a new narrative
0:14:50 > 0:14:54to explain those wall paintings of people in the sea.
0:14:54 > 0:14:57He first interpreted the figures in the water
0:14:57 > 0:15:01as underwater fishermen or sponge divers
0:15:01 > 0:15:04but later, he recognised them to be dead bodies,
0:15:04 > 0:15:06sinking to the bottom of the sea,
0:15:06 > 0:15:09casualties of some kind of naval engagement
0:15:09 > 0:15:12that seems to be taking place on the surface above them.
0:15:14 > 0:15:17The figures in the water may yet turn out to be
0:15:17 > 0:15:19evidence in favour of the invasion thesis.
0:15:23 > 0:15:28In the space of less than ten years, one important theory had emerged,
0:15:28 > 0:15:31been shot down and then replaced by another.
0:15:33 > 0:15:37It's very easy to look back and say they got it all wrong,
0:15:37 > 0:15:39but isn't this experimental approach
0:15:39 > 0:15:43what archaeology, science too, is all about -
0:15:43 > 0:15:46providing new answers to old questions
0:15:46 > 0:15:48with evidence that's constantly emerging?
0:15:53 > 0:15:58Science, if it's healthy, is a constant state of doubt.
0:15:58 > 0:16:02There are phrases like, "Scientists believe that..." -
0:16:02 > 0:16:05a phrase I hate because it doesn't represent
0:16:05 > 0:16:11this constant disagreement that has to go on in science or else it dies.
0:16:13 > 0:16:16And, of course, that wasn't the end of it.
0:16:18 > 0:16:21Discovering Atlantis is pretty much the Holy Grail
0:16:21 > 0:16:25for archaeologists and a perennial subject for TV documentaries.
0:16:27 > 0:16:33In 2002, film-makers once again reported that it HAD been found.
0:16:33 > 0:16:35But in a different part of Greece altogether.
0:16:35 > 0:16:40A separate team of archaeologists, digging on the Greek mainland,
0:16:40 > 0:16:42declared they'd found Atlantis...
0:16:44 > 0:16:49..and that it had been destroyed by a quite different natural disaster.
0:16:50 > 0:16:53This is the coast of Greece on the Corinthian Gulf,
0:16:53 > 0:16:56150km west of Athens.
0:16:56 > 0:17:00It is one of the most active earthquake regions in the world.
0:17:00 > 0:17:02According to old Roman texts,
0:17:02 > 0:17:08there was once a great Ancient Greek city here, called Helike.
0:17:12 > 0:17:162,500 years ago, Helike was a thriving metropolis.
0:17:19 > 0:17:23Over 5,000 people lived and worked within its walls
0:17:23 > 0:17:26and pilgrims thronged to its temple of Poseidon.
0:17:30 > 0:17:34But on one cold winter's night, in 373 BC,
0:17:34 > 0:17:38the god of earthquakes and the sea turned on his own people.
0:17:45 > 0:17:47The ancient sources said the earthquake struck at night
0:17:47 > 0:17:50when most people were caught in their houses.
0:17:54 > 0:17:58A massive tidal wave or tsunami or sea wave came in...
0:18:05 > 0:18:07..and swept away all survivors.
0:18:12 > 0:18:15Helike and all of its people were swept to the bottom of the sea,
0:18:15 > 0:18:18never to be seen again.
0:18:21 > 0:18:23Just a few short years after the disaster,
0:18:23 > 0:18:27the Greek writer Plato created the story of Atlantis.
0:18:35 > 0:18:39The archaeologists had been toiling here for 15 years,
0:18:39 > 0:18:42uncovering pottery and other artefacts,
0:18:42 > 0:18:44when they came upon structures
0:18:44 > 0:18:47which seemed to show signs of damage by tidal wave.
0:18:48 > 0:18:51Finally, in the walls below them,
0:18:51 > 0:18:54was possible evidence of the disaster itself.
0:18:54 > 0:18:58There were signs some huge force had struck the building.
0:18:59 > 0:19:01This wall has been knocked down toward the sea.
0:19:04 > 0:19:07That has the kind of pattern that you see when you have the backwash
0:19:07 > 0:19:10from the enormous wave going back to the sea...
0:19:12 > 0:19:15..and knocking them down in the direction of the sea.
0:19:18 > 0:19:21So, it seems that, after 15 long years of searching,
0:19:21 > 0:19:23their team may have succeeded
0:19:23 > 0:19:25where so many other archaeologists have failed.
0:19:27 > 0:19:30They believe these walls are just the first glimpses
0:19:30 > 0:19:34of the buildings that must lie in the ground around them.
0:19:34 > 0:19:38Beyond them, towards the hills, should lie the rest of the city,
0:19:38 > 0:19:40waiting to be uncovered.
0:19:42 > 0:19:45Now it seems the city whose destruction inspired
0:19:45 > 0:19:49the legend of Atlantis may finally have been found.
0:19:55 > 0:19:58So, was that the end of the quest for Atlantis?
0:20:02 > 0:20:05It's a mystery that just won't die.
0:20:05 > 0:20:10When Timewatch joined the search for Atlantis a decade later,
0:20:10 > 0:20:15the pendulum had swung right back to where it was in 1972.
0:20:16 > 0:20:21Historian Bettany Hughes went hunting for fresh evidence,
0:20:21 > 0:20:25homing in, once again, on the island of Santorini.
0:20:27 > 0:20:30Atlantis hunting is a fraught exercise
0:20:30 > 0:20:34but, precisely because it has generated so many wild theories,
0:20:34 > 0:20:40there's even more reason to try to sift the fact from the fiction.
0:20:42 > 0:20:46Fresh scientific evidence buttresses the idea that Plato's story
0:20:46 > 0:20:50was inspired by a real island and a real ancient civilisation
0:20:50 > 0:20:55that was destroyed by a real natural disaster...
0:20:58 > 0:21:03..an eruption on a scale the ancient world had never experienced before.
0:21:08 > 0:21:12This was an eruption that shook much of the planet.
0:21:12 > 0:21:15Ash was transported as far north as the Black Sea,
0:21:15 > 0:21:19as far east as central Turkey and as far south as the Nile Delta.
0:21:19 > 0:21:24Global temperatures dipped, stunting plant growth, even in Ireland.
0:21:30 > 0:21:33The early documentaries show a completely different picture
0:21:33 > 0:21:36from the modern ones, due to this advancement of science.
0:21:38 > 0:21:42New technologies, like satellite imagery, that we can now study,
0:21:42 > 0:21:45that give us a better global picture of what's happening,
0:21:45 > 0:21:49GPS, which records the relative movements on two sides of a fault
0:21:49 > 0:21:51before, during, after an earthquake.
0:21:51 > 0:21:54All of this instrumentation is providing us new data
0:21:54 > 0:21:57with which to study these natural events.
0:21:59 > 0:22:03For these film-makers, Santorini also seemed to fit perfectly
0:22:03 > 0:22:06with the description which Plato had provided.
0:22:10 > 0:22:14The first thing that strikes you is its really odd topography.
0:22:16 > 0:22:19The land just juts straight out of the sea
0:22:19 > 0:22:22and then you get these small islands, ringed by water,
0:22:22 > 0:22:24which are then, in turn, cradled
0:22:24 > 0:22:26by that massive semicircle of land up there.
0:22:29 > 0:22:32Now, just listen to what Plato has to say about his Atlantis.
0:22:35 > 0:22:38"There were circular belts of sea and land enclosing one another,
0:22:38 > 0:22:41"some greater, some smaller."
0:22:43 > 0:22:46Of course, that, in itself, doesn't prove anything.
0:22:46 > 0:22:49There could be loads of locations all round the world
0:22:49 > 0:22:50that match this description.
0:22:50 > 0:22:53But, nonetheless, this account
0:22:53 > 0:22:57and that landscape are really remarkably similar.
0:23:09 > 0:23:13Bettany's team had revived the 1972 theory
0:23:13 > 0:23:17that a massive tsunami had swept south from Santorini,
0:23:17 > 0:23:20smashing into the island of Crete.
0:23:20 > 0:23:25Evidence of the tsunami had now turned up on Crete itself.
0:23:26 > 0:23:30Archaeologist Sandy MacGillivray and tsunami expert, Costas Synolakis,
0:23:30 > 0:23:33are investigating the scale of the tsunamis
0:23:33 > 0:23:37by mapping pumice on Crete's northern coastline.
0:23:37 > 0:23:40Here's some. Here's a piece there.
0:23:41 > 0:23:44That's so light, isn't it? Mm-hmm.
0:23:44 > 0:23:48Cos it must have floated here, so... It's exactly what we like.
0:23:48 > 0:23:51I mean, flotsam that comes out gives us an idea
0:23:51 > 0:23:54of how high the wave reached.
0:23:54 > 0:23:57So, the tsunami would have carried this up here to this headland.
0:23:57 > 0:23:58At least to this point.
0:23:58 > 0:24:00It could have carried it further up
0:24:00 > 0:24:02and then it could have washed downriver
0:24:02 > 0:24:04with the rain, with floods.
0:24:04 > 0:24:08But this gives us, helps us bracket the size of the wave right offshore.
0:24:10 > 0:24:13Costas has developed a computer simulation
0:24:13 > 0:24:16of how the tsunamis would have travelled.
0:24:16 > 0:24:18This is the initial wave.
0:24:20 > 0:24:22We follow it all the way to Crete.
0:24:22 > 0:24:26The first wave causes the shoreline to retreat, to move offshore.
0:24:26 > 0:24:28We are less than an hour from the eruption
0:24:28 > 0:24:31and the red on the south side of Crete
0:24:31 > 0:24:36and the eastern Peloponnese are experiencing the big wave.
0:24:36 > 0:24:39What do you think, Sandy, that says about what happened to Crete,
0:24:39 > 0:24:43because most people live along the coast, don't they? I think so.
0:24:43 > 0:24:45There was the city of Knossos which is inland
0:24:45 > 0:24:48but, otherwise it's very much open coastline
0:24:48 > 0:24:52and so, the death toll would have been staggering.
0:24:54 > 0:24:56The hard evidence shows us
0:24:56 > 0:25:00that here, there was a sophisticated trading civilisation
0:25:00 > 0:25:04that flourished and was then swallowed by the sea,
0:25:04 > 0:25:08ravaged by a disaster of legendary proportions.
0:25:10 > 0:25:15Surely this is the root of Plato's Atlantis legend?
0:25:21 > 0:25:24So, it's clear that theories come and go.
0:25:24 > 0:25:27I suspect that's not the last we've heard of Atlantis.
0:25:30 > 0:25:32Certainly, for the moment at least,
0:25:32 > 0:25:35the evidence seems to favour Santorini
0:25:35 > 0:25:38as the true location for Plato's Atlantis.
0:25:39 > 0:25:41And it's brought home to me,
0:25:41 > 0:25:46just how new much of the underlying science really is.
0:25:46 > 0:25:49Tsunamis, in particular, are very poorly understood.
0:25:51 > 0:25:53I don't think a lot of people realise
0:25:53 > 0:25:56but, until the Indian Ocean tsunami, in 2004,
0:25:56 > 0:25:58we didn't even know what a tsunami wave looked like.
0:25:58 > 0:26:02It was only due to the complete chance of there being a vessel,
0:26:02 > 0:26:04measuring the depth of water offshore of Thailand
0:26:04 > 0:26:08when the tsunami passed under it, that we actually have a trace
0:26:08 > 0:26:13of what a tsunami wave looks like, and that's 2004.
0:26:15 > 0:26:19I'm going to look now at how film-makers have tried to keep pace
0:26:19 > 0:26:22with another branch of the Earth sciences.
0:26:23 > 0:26:27Just as with tsunamis, our understanding of volcanoes
0:26:27 > 0:26:30has massively increased in the last 40 years.
0:26:32 > 0:26:35In 1972, film-makers explored
0:26:35 > 0:26:38some of the brand-new discoveries in volcanology.
0:26:41 > 0:26:44EXPLOSION
0:26:44 > 0:26:48A volcano in eruption is undoubtedly the finest pyrotechnic display
0:26:48 > 0:26:51that man can ever see.
0:26:52 > 0:26:54These falls are twice the height of Niagara.
0:26:56 > 0:26:59And the fire fountain rises to almost 1,000 feet.
0:27:01 > 0:27:03Volcanoes can be docile or violent.
0:27:04 > 0:27:07In fact, volcanoes can vary enormously.
0:27:07 > 0:27:11Some lava flows like water, some is thicker than treacle.
0:27:16 > 0:27:19Volcanoes may have a far greater effect on the formation of the globe
0:27:19 > 0:27:22than the volcanologists at first suspected.
0:27:22 > 0:27:23Starting at the South Pacific,
0:27:23 > 0:27:25volcanoes spread right through Indonesia
0:27:25 > 0:27:29and up the island chain to Japan, Siberia and Alaska,
0:27:29 > 0:27:32down the west coast of America, with a loop round the Caribbean,
0:27:32 > 0:27:35though Mexico, Peru and Chile.
0:27:35 > 0:27:39It's not a random distribution. There are patterns.
0:27:40 > 0:27:43The structure of the Earth's crust is a series of rigid plates.
0:27:43 > 0:27:46Volcanoes help determine the plate boundaries.
0:27:51 > 0:27:54The film advances the then novel theory
0:27:54 > 0:27:56that all the land we now live on
0:27:56 > 0:28:00was at one time spewed from the mouth of an erupting volcano.
0:28:03 > 0:28:06The best information which we have available at the present time
0:28:06 > 0:28:10suggests that all the world's volcanoes, between them,
0:28:10 > 0:28:13are currently producing about three cubic kilometres
0:28:13 > 0:28:15of new material per year.
0:28:16 > 0:28:20At this rate, sustained through the course of geological time,
0:28:20 > 0:28:22the Earth's volcanoes would be capable of building up
0:28:22 > 0:28:25the whole of the continental crust.
0:28:25 > 0:28:29I think it's possible that the continental crust is, indeed,
0:28:29 > 0:28:32due to four and a half thousand million years of volcanism.
0:28:36 > 0:28:39This new understanding of volcanoes helped historians
0:28:39 > 0:28:42to better explain huge historic disasters,
0:28:42 > 0:28:47in particular the incredible story of Pompeii.
0:28:49 > 0:28:53This city in southern Italy, along with its neighbouring Herculaneum,
0:28:53 > 0:28:59was destroyed by a vast eruption of Mount Vesuvius in the year 79 AD.
0:29:04 > 0:29:08EXPLOSIONS
0:29:08 > 0:29:12The way that Pompeii citizens, who perished in the disaster,
0:29:12 > 0:29:16seem frozen in time has captured our imaginations.
0:29:16 > 0:29:20Their body outlines, preserved in the ashes,
0:29:20 > 0:29:23give a real sense of their final moments.
0:29:27 > 0:29:30More than 50 years ago, in 1966,
0:29:30 > 0:29:33presenter Robert Erskine introduced
0:29:33 > 0:29:37this remarkable story to the TV audience.
0:29:39 > 0:29:43Thousands of the townsfolk died, poisonous by the sulphurous fumes,
0:29:43 > 0:29:45in the basements of the houses and in the streets,
0:29:45 > 0:29:48because they couldn't make up their minds what to do.
0:29:48 > 0:29:51At the first cataclysmic explosion,
0:29:51 > 0:29:54the mountain split, split open,
0:29:54 > 0:29:58and it spewed its hideous innards all the way down this gulley,
0:29:58 > 0:30:00straight towards the town.
0:30:01 > 0:30:06Well, the inhabitants took one look and ran.
0:30:06 > 0:30:09Down these very streets, they fled in terror,
0:30:09 > 0:30:12away from the mountain, leaving everything behind them,
0:30:12 > 0:30:16doors and houses open, the wine bars precipitantly deserted,
0:30:16 > 0:30:19everything left where it was dropped in the terror of the moment.
0:30:19 > 0:30:21A blind panic flight, it must have been.
0:30:27 > 0:30:29By the early '70s,
0:30:29 > 0:30:32our new understanding of Earth science would deepen this knowledge.
0:30:34 > 0:30:38So, by 1974, film-makers could give
0:30:38 > 0:30:40a much more detailed account of the disaster.
0:30:42 > 0:30:44On Mount Vesuvius, broad sheets of fire
0:30:44 > 0:30:47and leaping flames blazed at several points.
0:30:48 > 0:30:51Ashes were already falling.
0:30:51 > 0:30:53The buildings were now shaking with violent shocks.
0:30:53 > 0:30:55Outside, on the other hand,
0:30:55 > 0:30:58there was the danger of falling pumice stones.
0:31:01 > 0:31:04We now know what actually happened.
0:31:04 > 0:31:07A violent blast of gas shot a huge cloud of ash and pumice
0:31:07 > 0:31:09miles into the air.
0:31:09 > 0:31:11Down fell a rain of lapilli, pieces of pumice,
0:31:11 > 0:31:14which buried the city to a depth of about ten feet.
0:31:14 > 0:31:18Some people fled, but many who sheltered in the houses
0:31:18 > 0:31:20were killed by buildings crumbling under the weight.
0:31:20 > 0:31:22Others were trapped and died.
0:31:25 > 0:31:27Survivors emerged into the open.
0:31:27 > 0:31:31It was then that a hurricane of scorching ash
0:31:31 > 0:31:32swept down the mountain.
0:31:35 > 0:31:38Those in flight, their lungs seared by the red-hot lava particles,
0:31:38 > 0:31:40collapsed in their tracks.
0:31:40 > 0:31:46About 2,000 bodies have been found so far, one-tenth of the population.
0:31:48 > 0:31:52The last minor eruption of Vesuvius was in 1944.
0:31:52 > 0:31:58For 30 years, the volcano has been silent, dangerously silent.
0:31:58 > 0:32:00But for how long?
0:32:07 > 0:32:09Vesuvius today looks like a volcano.
0:32:11 > 0:32:14Although you can climb to the top, no-one can be in much doubt
0:32:14 > 0:32:17of the explosive forces not very far below the surface.
0:32:19 > 0:32:25Vesuvius is a particularly dangerous volcano, capable of great violence.
0:32:25 > 0:32:29Always the cities of the Bay of Naples must live in fear.
0:32:29 > 0:32:33No-one can be sure when the mountain will split apart again.
0:32:37 > 0:32:40And the learning process still continues,
0:32:40 > 0:32:45fed by archaeology on one hand, volcanology on the other.
0:32:45 > 0:32:50We have a particular volcanic eruption - Vesuvius, AD 79.
0:32:50 > 0:32:55Our understanding of that is developing in two ways.
0:32:55 > 0:32:59Firstly, more excavations are being done around Vesuvius.
0:32:59 > 0:33:03But the other way is that we experience
0:33:03 > 0:33:06other eruptions of similar types.
0:33:08 > 0:33:12Therefore, you realise you can use the geophysical data,
0:33:12 > 0:33:15the observational data, and so on,
0:33:15 > 0:33:20of these different eruptions to understand AD 79.
0:33:23 > 0:33:25It's clear how our understanding has increased
0:33:25 > 0:33:28when you look at a much more recent film,
0:33:28 > 0:33:32which adopted a rigorously forensic approach to the disaster.
0:33:33 > 0:33:36In the early 1980s, a remarkable discovery was made
0:33:36 > 0:33:42at Herculaneum, which lies only 7km from Vesuvius, closer than Pompeii.
0:33:43 > 0:33:48300 skeletons were discovered, all victims of the volcanic eruption.
0:33:51 > 0:33:55But, to work out exactly what killed them, scientists needed to study
0:33:55 > 0:33:59another eruption that happened almost 2,000 years later.
0:34:01 > 0:34:05The results appeared in a film, presented by Roman history scholar
0:34:05 > 0:34:09and one-time Apprentice panellist Margaret Mountford.
0:34:13 > 0:34:16What force was hot enough to reduce these poor people
0:34:16 > 0:34:18to a pile of scorched bones?
0:34:21 > 0:34:23We need to look at a volcano that erupted in North America
0:34:23 > 0:34:25in the 1980s.
0:34:31 > 0:34:33Mount St Helens National Park has
0:34:33 > 0:34:36some of the most breathtaking scenery in the USA.
0:34:38 > 0:34:44But on Sunday, May 18th, 1980, this peaceful world was transformed
0:34:44 > 0:34:47when the Mount St Helens volcano erupted.
0:34:50 > 0:34:54EXPLOSIONS
0:34:58 > 0:35:01Volcanologists had seen eruptions before,
0:35:01 > 0:35:03but this was the first time
0:35:03 > 0:35:06they had managed to capture on film a little-known phenomenon.
0:35:08 > 0:35:12The whole north face of Mount St Helens collapses.
0:35:15 > 0:35:18As it does, it releases a searing-hot avalanche
0:35:18 > 0:35:22of gas and dust that explodes down the sides of the mountain.
0:35:24 > 0:35:27This is called a pyroclastic current.
0:35:29 > 0:35:33The turbulent wave of gas measured 700 degrees Celsius
0:35:33 > 0:35:37and travelled at nearly 500km an hour.
0:35:38 > 0:35:42Can you explain what a pyroclastic current is?
0:35:42 > 0:35:45A pyroclastic current is an avalanche
0:35:45 > 0:35:48of searing-hot gas, ash and rock
0:35:48 > 0:35:50that travels down the slopes of a volcano
0:35:50 > 0:35:53at hundreds of kilometres an hour.
0:35:53 > 0:35:56It's impossible to outrun and absolutely deadly.
0:35:56 > 0:35:59When I think of an eruption, I think of streams of lava
0:35:59 > 0:36:01coming down a mountain.
0:36:01 > 0:36:05Well, the style of eruption - whether a volcano will erupt lava
0:36:05 > 0:36:08or if it will erupt explosively -
0:36:08 > 0:36:12is primarily a function of how much gas is in the magma.
0:36:12 > 0:36:14If there is no gas in the magma,
0:36:14 > 0:36:18then the magma will erupt as a lava flow or a lava dome.
0:36:18 > 0:36:19And that is the actual magma,
0:36:19 > 0:36:23the liquefied rock that's coming out as lava. Exactly.
0:36:23 > 0:36:24And, in an explosive eruption,
0:36:24 > 0:36:27the difference is the magma has gas bubbles
0:36:27 > 0:36:31and as the gas in the magma makes its way to the surface,
0:36:31 > 0:36:33the gas bubbles get bigger and bigger and bigger,
0:36:33 > 0:36:36to the point where, when the volcano erupts,
0:36:36 > 0:36:38the gases expand very quickly
0:36:38 > 0:36:41and it rips the magma apart into very tiny pieces,
0:36:41 > 0:36:43which are your ash and your pumice.
0:36:45 > 0:36:48From what scientists witnessed at Mount St Helens,
0:36:48 > 0:36:51and data gathered from other volcanic eruptions,
0:36:51 > 0:36:53it's now possible to piece together
0:36:53 > 0:36:56exactly what happened when Vesuvius erupted.
0:36:57 > 0:37:00EXPLOSION
0:37:00 > 0:37:0312 hours after the initial eruption,
0:37:03 > 0:37:07the column above Vesuvius stretched nearly 32km high.
0:37:09 > 0:37:12But under its own weight, it collapsed.
0:37:15 > 0:37:18A pyroclastic current surged down the sides of the volcano
0:37:18 > 0:37:21at speeds up 300km an hour.
0:37:28 > 0:37:32Temperatures inside the explosive blast were over 500 degrees Celsius.
0:37:38 > 0:37:42The wave of searing-hot gas and ash took less than five minutes
0:37:42 > 0:37:46to strike Herculaneum 7km away.
0:37:58 > 0:38:01The intense heat surge killed them instantly.
0:38:05 > 0:38:08It vaporised their flesh.
0:38:16 > 0:38:18And that is why all that remained
0:38:18 > 0:38:22were blackened skeletons and cracked skulls.
0:38:26 > 0:38:31This new insight into volcanoes gives historians a toolkit
0:38:31 > 0:38:36with which to investigate previously unexplained events from the past.
0:38:38 > 0:38:41We get new data all the time.
0:38:41 > 0:38:44We didn't have a concept of the pyroclastic flow
0:38:44 > 0:38:47and what pyroclastic flows did to people.
0:38:47 > 0:38:50So, this constant drawing of information from other areas,
0:38:50 > 0:38:52and comparisons and analogies,
0:38:52 > 0:38:55means that the science is changing all the time.
0:38:56 > 0:38:59The depth of knowledge which now exists
0:38:59 > 0:39:01about the Vesuvius eruption shows
0:39:01 > 0:39:06that with historians, scientists and film-makers working together,
0:39:06 > 0:39:09it is possible to take an old mystery
0:39:09 > 0:39:11and supply a definitive answer.
0:39:12 > 0:39:16Bur my trawl through the film archive shows there are still areas
0:39:16 > 0:39:18where that's not at all true.
0:39:18 > 0:39:22One of the deadliest disasters ever to strike the planet
0:39:22 > 0:39:24still has no known cause.
0:39:25 > 0:39:29Or at least no cause which experts can agree on.
0:39:31 > 0:39:35It was an epidemic which killed tens of millions of people
0:39:35 > 0:39:39and could, some experts fear, reappear today.
0:39:40 > 0:39:43650 years ago, the so-called Black Death
0:39:43 > 0:39:45is thought to have wiped out
0:39:45 > 0:39:48something close to a third of Europe's population.
0:39:49 > 0:39:53But, as Timewatch reported in 1984,
0:39:53 > 0:39:58the epidemic raises maybe the biggest question in medical history.
0:40:00 > 0:40:03The cause of that holocaust, historians believe, was plague -
0:40:03 > 0:40:07more specifically, bubonic and pneumonic plague.
0:40:07 > 0:40:11New biological research, however, is coming to a different conclusion.
0:40:15 > 0:40:18The time-honoured theory was that bubonic plague had been spread
0:40:18 > 0:40:20by black rats.
0:40:21 > 0:40:25The fleas that live on the rats, but also feed on humans,
0:40:25 > 0:40:28were thought to be the way the disease was transmitted.
0:40:28 > 0:40:32But did this theory add up, in the light of new evidence?
0:40:35 > 0:40:39The Black Death first arrived in Britain on the Dorset coast.
0:40:40 > 0:40:44By the end of 1348, it had most of southern England in its grip.
0:40:44 > 0:40:47Six months later, it had spread through Wales,
0:40:47 > 0:40:49the Midlands and East Anglia.
0:40:49 > 0:40:52By the end of 1349, it had reached the Scottish Highlands
0:40:52 > 0:40:54and the North of Ireland.
0:40:54 > 0:40:56It moved across the country at about a mile a day
0:40:56 > 0:41:00or even a little more than that, depending whose account you follow.
0:41:00 > 0:41:03Now, this just doesn't fit in with what we know of plague today.
0:41:03 > 0:41:08The winter of 1348 to '49 was unusually cold.
0:41:08 > 0:41:12But bubonic plague does not appear to thrive in low temperatures.
0:41:12 > 0:41:14The black rat is an animal
0:41:14 > 0:41:15that likes the warmth.
0:41:15 > 0:41:18It comes from India, basically, in that region.
0:41:18 > 0:41:21The flea is very temperature dependent.
0:41:23 > 0:41:25It only breeds when the temperature gets
0:41:25 > 0:41:30between 65 and 85 degrees Fahrenheit and when the humidity is right.
0:41:33 > 0:41:37According to Dr Twigg, there just weren't enough rats and fleas
0:41:37 > 0:41:40to spread bubonic plague across Britain so rapidly
0:41:40 > 0:41:42and with such fearful loss of life.
0:41:44 > 0:41:47But if it wasn't bubonic plague, what was it?
0:41:48 > 0:41:51One disease that fits the bill rather well would be anthrax.
0:41:53 > 0:41:56Unlike bubonic plague, it can spread from person to person.
0:41:56 > 0:41:59It's found, to a great extent,
0:41:59 > 0:42:02in domesticated animals - cattle and sheep.
0:42:03 > 0:42:06But, in a human being, when the spore gets into the body,
0:42:06 > 0:42:08haemorrhages occur.
0:42:09 > 0:42:14The body oozes dark blood from all the bodily orifices.
0:42:17 > 0:42:20The fact that anthrax, rather than bubonic plague,
0:42:20 > 0:42:22might have been the culprit shows, perhaps,
0:42:22 > 0:42:26how little we really know about this huge episode in history...
0:42:28 > 0:42:31..and how difficult it is for film-makers
0:42:31 > 0:42:34to offer a definitive account,
0:42:34 > 0:42:37with research constantly being updated.
0:42:37 > 0:42:41When Timewatch returned to the question in 2004,
0:42:41 > 0:42:43yet another possible candidate
0:42:43 > 0:42:45for the killer disease had entered the frame.
0:42:47 > 0:42:50The biologist is convinced he's found the answer
0:42:50 > 0:42:52to the mystery of the Black Death.
0:42:52 > 0:42:54Historians have spent a lot of time
0:42:54 > 0:42:57interpreting what went on,
0:42:57 > 0:43:01in terms of rats and fleas, which is incorrect
0:43:01 > 0:43:03and I think we need the record straightened out.
0:43:05 > 0:43:09Professor Duncan's analysis is controversial
0:43:09 > 0:43:12but he's willing to speculate on the actual identity of the killer
0:43:12 > 0:43:16which terrorised Europe for over 300 years.
0:43:16 > 0:43:18His guess is based on symptoms
0:43:18 > 0:43:22mentioned in some of the 14th-century accounts.
0:43:23 > 0:43:26"Sudden fever, spitting blood and saliva
0:43:26 > 0:43:29"and no-one who spat blood survived it."
0:43:29 > 0:43:33"Brought on by an affliction of the head of vomiting blood."
0:43:33 > 0:43:37"The accompanying putrefaction of humours
0:43:37 > 0:43:40"caused the victim to cough up blood."
0:43:43 > 0:43:45Could these be medieval descriptions
0:43:45 > 0:43:48of someone dying of internal haemorrhaging?
0:43:50 > 0:43:54From the symptoms, it has got features in common with Ebola.
0:43:57 > 0:44:01Ebola is one of the deadliest diseases on Earth.
0:44:01 > 0:44:04It's caused by a tiny threadlike virus,
0:44:04 > 0:44:07which was first isolated 30 years ago in Africa.
0:44:09 > 0:44:14It causes a wide range of symptoms - fever, coughing up blood
0:44:14 > 0:44:17and, occasionally, lumps under the skin.
0:44:20 > 0:44:23The tragedy that was played out across medieval Europe
0:44:23 > 0:44:25no longer seems to be easily explained
0:44:25 > 0:44:29as an epidemic of bubonic plague, spread by fleas.
0:44:29 > 0:44:32We are in the uneasy position of not knowing the cause
0:44:32 > 0:44:36of the most deadly epidemic ever to strike humanity.
0:44:37 > 0:44:42And until we know, we can't be sure we could stop it happening again.
0:44:49 > 0:44:51So, now two possible new diagnoses.
0:44:53 > 0:44:56One of this country's leading authorities on epidemics
0:44:56 > 0:45:01believes the Black Death could even have been a series of diseases,
0:45:01 > 0:45:04striking around the same time.
0:45:04 > 0:45:07I don't place all that much reliance on anyone, myself included,
0:45:07 > 0:45:10coming up and saying, "This is the answer.
0:45:10 > 0:45:13"It's not the plague bacillus, it's the anthrax bacillus
0:45:13 > 0:45:16"or it's Ebola, or it's this or it's that or it's something else."
0:45:16 > 0:45:20It's bad enough to get things diagnosed today, and I mean today.
0:45:20 > 0:45:22Imagine what it's like 800 years ago.
0:45:24 > 0:45:27I suspect, myself, there were deaths of all kinds of things,
0:45:27 > 0:45:29all kinds of things,
0:45:29 > 0:45:33and it's too easy to throw them all into the bubonic plague pot.
0:45:33 > 0:45:35That's why I'm sceptical about it.
0:45:38 > 0:45:43It would be wrong to be too harsh about these conflicting diagnoses.
0:45:43 > 0:45:47After all, the second opinion is a long-established tradition.
0:45:48 > 0:45:51But it does serve as a warning
0:45:51 > 0:45:55about looking for certainty where it simply may not exist.
0:45:56 > 0:45:59After studying these films, I think one of the reasons
0:45:59 > 0:46:02why disaster documentaries are so fascinating
0:46:02 > 0:46:08is that they make you wonder, "Am I safe? Could it ever happen here?"
0:46:10 > 0:46:13Could a lovely beach like this, Dunraven Bay in south Wales,
0:46:13 > 0:46:17really be the location for a huge natural disaster?
0:46:20 > 0:46:24Timewatch revealed that's not as farfetched as it sounds.
0:46:27 > 0:46:31400 years ago, the entire coastline of the Bristol Channel
0:46:31 > 0:46:33was engulfed by an enormous flood.
0:46:35 > 0:46:37The question is, what caused it?
0:46:41 > 0:46:47On 20th January, 1607, a wall of water up to ten metres high
0:46:47 > 0:46:50rushed over the low-lying sea defences.
0:46:58 > 0:47:01Travelling at 30mph, the killer wave bore down
0:47:01 > 0:47:04on the villages of Somerset and Monmouthshire.
0:47:16 > 0:47:20It came without warning and left 2,000 dead in its wake.
0:47:21 > 0:47:22Yet, for centuries,
0:47:22 > 0:47:25this apocalyptic flood has been forgotten,
0:47:25 > 0:47:29and only now are scientists piecing together the evidence left behind.
0:47:30 > 0:47:33Was it just a huge storm
0:47:33 > 0:47:38or was the killer wave of 1607 in fact a British tsunami?
0:47:43 > 0:47:48It was a very timely question when this film appeared in 2005.
0:47:49 > 0:47:52The terrible Boxing Day tsunami off Indonesia,
0:47:52 > 0:47:54with a quarter of a million people dead,
0:47:54 > 0:47:57was still fresh in everyone's mind.
0:48:03 > 0:48:05The film looks at new research,
0:48:05 > 0:48:09suggesting the flood had many of the characteristics of a tsunami,
0:48:09 > 0:48:14in particular, the way the rocks are laid out on this beach.
0:48:17 > 0:48:19At Dunraven Bay in south Wales,
0:48:19 > 0:48:22hundreds of boulders lie at the foot of the cliffs.
0:48:22 > 0:48:25Some have obviously just dropped off the face,
0:48:25 > 0:48:28but others are less easy to explain.
0:48:28 > 0:48:31This particular boulder, I'm pretty sure,
0:48:31 > 0:48:33has been moved off the beach.
0:48:33 > 0:48:36It's got some fossils in it which you don't normally associate
0:48:36 > 0:48:38with the older limestones
0:48:38 > 0:48:39which you find on the cliffs here.
0:48:39 > 0:48:41So, it looks like this quite big boulder
0:48:41 > 0:48:44has come from over there on the beach.
0:48:45 > 0:48:48The force of water needed to move seven-tonne boulders
0:48:48 > 0:48:51could easily be produced by a tsunami.
0:48:51 > 0:48:55The way the boulders are lying gives Simon another clue.
0:48:56 > 0:48:59That's 270 degrees west.
0:48:59 > 0:49:01Certainly storms can move the odd boulder
0:49:01 > 0:49:03and can fling boulders up onto the top of cliffs
0:49:03 > 0:49:06but, given that we've got so many boulders in a train,
0:49:06 > 0:49:08what we call a boulder train,
0:49:08 > 0:49:11and they're all pointing back in the same direction,
0:49:11 > 0:49:15that suggests to us a constant flow over time.
0:49:17 > 0:49:20It would only have taken a five-metre tsunami wave
0:49:20 > 0:49:21to shift these boulders.
0:49:21 > 0:49:26For a storm to do the same thing, they calculate it would have taken
0:49:26 > 0:49:29a wave at least 20 metres high, over 60 feet.
0:49:31 > 0:49:34Yet the very idea of a tsunami laying waste to the Bristol Channel
0:49:34 > 0:49:36goes against every assumption we have
0:49:36 > 0:49:39about Britain being geologically safe.
0:49:40 > 0:49:45The big surprise is that the seabed off the southwest tip of Ireland
0:49:45 > 0:49:48is the location of an ancient but massive faultline.
0:49:50 > 0:49:54On 8th February, 1980, sensors recorded an earthquake
0:49:54 > 0:49:59from exactly this area, 4.5 on the Richter scale,
0:49:59 > 0:50:03violent enough to give fresh impetus to the tsunami theory.
0:50:06 > 0:50:09I think I've got the dark layer here.
0:50:09 > 0:50:12I really like that style of film-making.
0:50:12 > 0:50:14I think that's quite a change
0:50:14 > 0:50:15from something of the 1970s,
0:50:15 > 0:50:18the way that the evidence is presented.
0:50:18 > 0:50:21Quite thin here. It's coming to about ten centimetres.
0:50:21 > 0:50:25The dilemma scientists actually have themselves about the evidence
0:50:25 > 0:50:28which, of course, has a great deal of uncertainty about it.
0:50:28 > 0:50:33The film-makers are careful to say that much more evidence is needed
0:50:33 > 0:50:35before the theory is widely accepted.
0:50:37 > 0:50:40But the thought of an undersea earthquake zone,
0:50:40 > 0:50:43just a short distance off the British coast,
0:50:43 > 0:50:47is an intriguing hypothesis and a scary one, too.
0:50:49 > 0:50:52The last film I'm going to look at is especially chilling
0:50:52 > 0:50:54because it assembles compelling evidence
0:50:54 > 0:50:57for disaster that's yet to happen.
0:51:05 > 0:51:06This is the story
0:51:06 > 0:51:09of how the greatest natural disaster
0:51:09 > 0:51:12in human history might one day unfold.
0:51:14 > 0:51:16The biggest wave ever seen...
0:51:17 > 0:51:20..threatening death and devastation
0:51:20 > 0:51:22on an unprecedented scale.
0:51:29 > 0:51:31The power of this film lies in the fact
0:51:31 > 0:51:35that it's based on a genuine scientific hypothesis,
0:51:35 > 0:51:38yet it uses all the visual tricks
0:51:38 > 0:51:40of the classic disaster movie.
0:51:41 > 0:51:44The film reports a study of a volcano in the Canary Islands.
0:51:46 > 0:51:48Some scientists fear that an eruption
0:51:48 > 0:51:53would cause the volcano to crumble, producing a huge landslide.
0:51:53 > 0:51:55That, in turn,
0:51:55 > 0:52:00could displace enough water to trigger a mega tsunami.
0:52:01 > 0:52:04The film goes on to imagine the terrible consequences
0:52:04 > 0:52:07if a disaster like that happened for real.
0:52:10 > 0:52:13Travelling at up to 800 millions an hour,
0:52:13 > 0:52:17the giant wave surges out in all directions.
0:52:17 > 0:52:19Immediately in its path,
0:52:19 > 0:52:23the highly populated island of Tenerife.
0:52:24 > 0:52:26Locals and holiday-makers alike
0:52:26 > 0:52:28do all they can to outrun it.
0:52:42 > 0:52:43Within minutes,
0:52:43 > 0:52:46the wave has claimed its first victims.
0:52:47 > 0:52:50I don't think there's any doubt
0:52:50 > 0:52:52that the initial wave will be
0:52:52 > 0:52:55very catastrophic for the islands themselves.
0:52:57 > 0:53:00So you're talking about thousands of people dead
0:53:00 > 0:53:02and destruction on a scale that we've never seen
0:53:02 > 0:53:04in this part of the world before.
0:53:06 > 0:53:09Our mega tsunami's journey of destruction
0:53:09 > 0:53:11has only just begun.
0:53:11 > 0:53:13Over the following hours,
0:53:13 > 0:53:17these waves will devastate the coastlines of Europe.
0:53:19 > 0:53:22The emergency services have just three hours
0:53:22 > 0:53:25before the wave strikes Britain.
0:53:27 > 0:53:29The Environment Agency issues flood warnings
0:53:29 > 0:53:31to the south coast
0:53:31 > 0:53:34and rescue units are put on standby.
0:53:36 > 0:53:39Police clear the streets of southern coastal towns,
0:53:39 > 0:53:44evacuating schools and vulnerable communities.
0:53:44 > 0:53:46A giant tsunami is spreading
0:53:46 > 0:53:47throughout the Atlantic Basin.
0:53:47 > 0:53:50Scientists estimate that the wave is travelling
0:53:50 > 0:53:53at approximately 500mph.
0:53:54 > 0:53:57Just three hours after the first UK warnings,
0:53:57 > 0:54:00a wave up to 25 metres high
0:54:00 > 0:54:03makes its first landfall in Britain...
0:54:05 > 0:54:07..on Cornwall.
0:54:18 > 0:54:20From Cornwall, the wave surges
0:54:20 > 0:54:22through the English Channel,
0:54:22 > 0:54:25engulfing much of Britain's south coast.
0:54:33 > 0:54:36In our scenario, London, our capital,
0:54:36 > 0:54:40tucked in from the North Sea, is safely sheltered.
0:54:42 > 0:54:45Models differ on what the wave might do
0:54:45 > 0:54:48to our southern cities, as it works its way east.
0:54:50 > 0:54:53Towns such as Brighton would suffer serious disruption.
0:54:58 > 0:55:01We can get some idea of the impact
0:55:01 > 0:55:04of a seven to ten-metre wave on the UK south coast,
0:55:04 > 0:55:07by looking at what happened in the Indian Ocean in 2004
0:55:07 > 0:55:09in places like Sri Lanka and Thailand.
0:55:10 > 0:55:13The death toll was in the tens of thousands.
0:55:13 > 0:55:15The population on the south coast of the UK
0:55:15 > 0:55:17is probably quite a bit higher,
0:55:17 > 0:55:21so that sort of wave would be immensely destructive in the UK.
0:55:21 > 0:55:24But the greatest carnage would be inflicted
0:55:24 > 0:55:27on the USA, with east coast cities like New York,
0:55:27 > 0:55:30directly in the path of the tsunami.
0:55:30 > 0:55:35New York, Boston, Washington, Miami.
0:55:35 > 0:55:38Entire cities have been destroyed.
0:55:40 > 0:55:42The number of casualties
0:55:42 > 0:55:44is really hard to get at in something like this.
0:55:44 > 0:55:47For the 25-metre scenario,
0:55:47 > 0:55:50with maybe three to four hours' warning,
0:55:50 > 0:55:53we came up with roughly 4.5 million causalities.
0:55:55 > 0:55:57Around the world, there may be
0:55:57 > 0:55:59one of these enormous events
0:55:59 > 0:56:04maybe once every 20,000 years, maybe only once every 50,000 years.
0:56:05 > 0:56:08We can't say when the collapse is going to occur.
0:56:09 > 0:56:13It seems to already be close to failure.
0:56:15 > 0:56:21So, the crucial question is not a matter of if, but of when.
0:56:21 > 0:56:24EXPLOSION
0:56:32 > 0:56:37If the worst were to happen, then at least WE'D have some warning,
0:56:37 > 0:56:41unlike the people of Pompeii or maybe Atlantis,
0:56:41 > 0:56:43who were suddenly overwhelmed
0:56:43 > 0:56:47by forces they could only ascribe to the angry gods.
0:56:50 > 0:56:53Given that we've only just begun to understand
0:56:53 > 0:56:56what's happening beneath the Earth's surface in the past few decades,
0:56:56 > 0:57:00it's little wonder that they looked for supernatural explanation
0:57:00 > 0:57:02more than 3,000 years ago.
0:57:03 > 0:57:06My trawl through the film archive clearly shows
0:57:06 > 0:57:09that we've learnt a huge amount about natural disasters
0:57:09 > 0:57:12in the last half-century,
0:57:12 > 0:57:16and we've learnt so fast that it's hard for film-makers to keep up.
0:57:16 > 0:57:19It's our scientific responsibility to be very humble
0:57:19 > 0:57:21about the limitations of this knowledge
0:57:21 > 0:57:25and what it's based on, but also invite debate.
0:57:25 > 0:57:30It's important that new discoveries, that new theories are debated.
0:57:30 > 0:57:32There has to be an acknowledgement that science changes.
0:57:32 > 0:57:37As a scientist, I treat these films as a snapshot
0:57:37 > 0:57:41that captures our understanding at a certain point in time.
0:57:41 > 0:57:45These documentaries, whatever their imperfections, their flaws
0:57:45 > 0:57:49and their distortions and all the complaints, you know,
0:57:49 > 0:57:52"Things aren't being represented, it's not certain science,"
0:57:52 > 0:57:55but it's describing possibilities,
0:57:55 > 0:58:00and it's possibilities the knowledge of which may save lives.
0:58:01 > 0:58:05As these films evolve, it's like actually being an observer
0:58:05 > 0:58:10during the discovery process and I'm all in favour of that.
0:58:12 > 0:58:16As the years go by, we understand more and more,
0:58:16 > 0:58:19so I don't think we've seen the last documentary
0:58:19 > 0:58:25on what happened 3,000 years ago in Atlantis, or Pompeii or even here.
0:59:02 > 0:59:04Detective Griffin?
0:59:04 > 0:59:05Are you good? You all right?
0:59:05 > 0:59:06Pleased to be back.
0:59:06 > 0:59:09Your baby has been loved by me very much.
0:59:09 > 0:59:10I'd like to say thank you.
0:59:11 > 0:59:13I like you.
0:59:13 > 0:59:15We have a report there's a suitcase washed up.
0:59:15 > 0:59:18There's black human hair coming from the inside.