0:00:05 > 0:00:07For all our technological wonders,
0:00:07 > 0:00:12mankind is vulnerable to a far greater power.
0:00:15 > 0:00:20The wrath and fury that only our planet can unleash.
0:00:25 > 0:00:28Volcanoes...
0:00:28 > 0:00:30earthquakes...
0:00:30 > 0:00:35and silent assassins, unseen until it's too late.
0:00:43 > 0:00:48Tsunamis that bring death and devastation from the sea.
0:00:53 > 0:00:56On Boxing Day 2004,
0:00:56 > 0:01:00nearly a quarter of a million people were killed in southern Asia.
0:01:02 > 0:01:06On March 11, 2011, Japan
0:01:06 > 0:01:11and destruction that came within a whisker of nuclear catastrophe.
0:01:13 > 0:01:15But scientists believe
0:01:15 > 0:01:19that something even more destructive lies in wait.
0:01:19 > 0:01:23Something that will one day strike us in the West.
0:01:25 > 0:01:30A wave so many times bigger than any conventional tsunami,
0:01:30 > 0:01:34it's been dubbed a mega-tsunami.
0:01:46 > 0:01:54Now, using the very latest science, powerful computer models
0:01:54 > 0:01:58and the terrible evidence of all to recent events,
0:01:58 > 0:02:01this is the story of how some experts believe the greatest
0:02:01 > 0:02:06natural disaster in human history might one day unfold.
0:02:10 > 0:02:13The biggest wave ever seen...
0:02:13 > 0:02:16threatening cataclysmic destruction
0:02:16 > 0:02:19of some of the world's greatest cities...
0:02:22 > 0:02:27..death and devastation on an unprecedented scale
0:02:27 > 0:02:31and economic fallout that could reshape the future
0:02:31 > 0:02:33of the entire world.
0:02:52 > 0:02:55It will all begin on one of Britain's most popular
0:02:55 > 0:02:58tourist resorts...
0:02:58 > 0:03:00the Canary Islands,
0:03:00 > 0:03:04with an event that last occurred in 1971
0:03:04 > 0:03:07and, before that, in 1949.
0:03:11 > 0:03:13A volcanic eruption.
0:03:13 > 0:03:16'The Canary Islands' volcano of La Palma
0:03:16 > 0:03:18'erupted for the first time in two centuries.
0:03:18 > 0:03:20'Menacing the population
0:03:20 > 0:03:23'and is turning night into day with blazing rivers of molten lava.'
0:03:30 > 0:03:33People think of volcanoes of being, sort of, cone shaped
0:03:33 > 0:03:35with a little hole in the top
0:03:35 > 0:03:37and those are what we called stratovolcanoes,
0:03:37 > 0:03:39they are the traditional volcano shape,
0:03:39 > 0:03:43but this is very different, this is an elongate structure.
0:03:48 > 0:03:51La Palma is one of a chain of volcanic islands,
0:03:51 > 0:03:53lying off the coast of West Africa,
0:03:53 > 0:03:56that includes Gran Canaria and Tenerife.
0:04:01 > 0:04:04Its most active region is a high mountain ridge
0:04:04 > 0:04:06called La Cumbre Vieja.
0:04:08 > 0:04:12The Cumbre Vieja occupies the southernmost part of the island
0:04:12 > 0:04:16and it forms this north-south lined ridge.
0:04:16 > 0:04:19The whole ridge is, sort of, pockmarked craters and holes,
0:04:19 > 0:04:22and then you have lava flows heading off in both directions,
0:04:22 > 0:04:25to the west and east, from these particular craters.
0:04:30 > 0:04:36In 1949, quite a small eruption, in terms of volume of lava,
0:04:36 > 0:04:39the volume of magma, erupted but during the eruption
0:04:39 > 0:04:42there had been a series of very strong earthquakes
0:04:42 > 0:04:46and a fault line had developed along the crest of the volcano.
0:04:51 > 0:04:55A giant gash had opened up along the island's ridge,
0:04:55 > 0:04:59four kilometres long and up to four metres wide.
0:05:02 > 0:05:07Part of the west flank dropped a couple of metres towards the sea
0:05:07 > 0:05:10and then stopped, and that's really what tells us that something
0:05:10 > 0:05:13other than just magma coming up was going on during that eruption.
0:05:19 > 0:05:23That geological rift is the reason why this volcano
0:05:23 > 0:05:27could one day trigger a mega-tsunami.
0:05:32 > 0:05:35Because ever since 1949,
0:05:35 > 0:05:41the peaceful island of La Palma has been a time bomb...
0:05:41 > 0:05:45and some scientists believe that today another eruption
0:05:45 > 0:05:50could send 500 cubic kilometres of it crashing into the sea.
0:05:53 > 0:05:56A colossal landslide with enough energy
0:05:56 > 0:06:00to generate the biggest wave humanity will have ever seen.
0:06:02 > 0:06:08Unleashed not upon the Pacific but the Atlantic and heading for us...
0:06:10 > 0:06:14..the first mega-tsunami in recorded history.
0:06:30 > 0:06:33The terrible human cost of the recent Pacific tsunamis
0:06:33 > 0:06:36came from underwater earthquakes.
0:06:44 > 0:06:49But recent history has already shown that the collapse of a volcano
0:06:49 > 0:06:52could unleash even greater devastation.
0:06:54 > 0:06:58Most people think of volcanoes as these are unchanging sentinels
0:06:58 > 0:07:00of solid rock that persists for many millions of years
0:07:00 > 0:07:03and, really, just go on getting bigger,
0:07:03 > 0:07:07but they are better viewed, really, as unstable piles of rubble.
0:07:08 > 0:07:12It was the Mount St Helens eruption in 1980 that really provided us
0:07:12 > 0:07:16with that first visual proof that volcanoes did collapse.
0:07:16 > 0:07:20'This is the CBS Evening News with Dan Rather.'
0:07:20 > 0:07:23It is an event that defies superlatives.
0:07:23 > 0:07:27One geologist said today, "There is no record today, in geology,
0:07:27 > 0:07:31"in the last 4,000 years, of anything like this happening before.
0:07:31 > 0:07:34"The tremendous lateral blast is unprecedented."
0:07:35 > 0:07:38This is the only photographic evidence that we have
0:07:38 > 0:07:42for a volcano lateral collapse actually happening.
0:07:42 > 0:07:45'This sequence of photos was taken during the first 60 seconds
0:07:45 > 0:07:47'of the mountain's eruption,
0:07:47 > 0:07:50'beginning shortly after 8.30 on Sunday morning.'
0:07:51 > 0:07:54It was really an iconic moment, which taught us that volcanoes
0:07:54 > 0:07:57did things that we didn't think they did before, and that is that
0:07:57 > 0:08:01instead of just erupting upwards they can also erupt sideways.
0:08:05 > 0:08:08You can see the bulge dislodging,
0:08:08 > 0:08:11forming this landslide which heads off northwards.
0:08:14 > 0:08:18And then this massive column of ash, which heads up into the atmosphere,
0:08:18 > 0:08:20and ultimately covers the entire region.
0:08:22 > 0:08:25The question we all asked ourselves at the time was,
0:08:25 > 0:08:28"What would've happened if that collapse had occurred into water?"
0:08:31 > 0:08:34What would happen would be the conversion
0:08:34 > 0:08:37of a vast amount of energy into an ocean-going wave...
0:08:39 > 0:08:42..starting off up to one kilometre high
0:08:42 > 0:08:47and with the power to cross oceans at the speed of a jet aircraft...
0:08:48 > 0:08:52..ready to make landfall with potentially apocalyptic results.
0:09:08 > 0:09:11Startlingly, it wouldn't be the first time that a landslide
0:09:11 > 0:09:15has called a tsunami on the Canary Islands.
0:09:15 > 0:09:20One marine geologist thinks he's found evidence of a past event...
0:09:25 > 0:09:31..not on La Palma but nearby on Gran Canaria
0:09:31 > 0:09:33at a site called Agaete.
0:09:36 > 0:09:43What we have here are tiny pieces of shell - that's about two centimetres.
0:09:43 > 0:09:46That's a mollusc, it comes from the sea.
0:09:46 > 0:09:50What is strange about finding them here
0:09:50 > 0:09:55is that they are 50 metres above...
0:09:55 > 0:09:59the level in the sea at which they usually live.
0:10:00 > 0:10:04Shells like these can be found three kilometres inland
0:10:04 > 0:10:07and 200 metres above the sea -
0:10:07 > 0:10:11too far to have been carried there by any storm.
0:10:11 > 0:10:14And, without evidence of changes in sea level,
0:10:14 > 0:10:17there can be only one explanation.
0:10:17 > 0:10:20If they weren't laid down by a high sea level,
0:10:20 > 0:10:24if they weren't laid down by a storm, then what was the source?
0:10:25 > 0:10:30We need something to have created a wave 200 metres high.
0:10:35 > 0:10:39Dave Tappin's wave on Gran Canaria was far too big
0:10:39 > 0:10:41to have been made by an earthquake.
0:10:42 > 0:10:48The only answer, in my estimation, is the collapse of a volcano.
0:10:48 > 0:10:54It's unlikely to have been Gran Canaria but the nearest island,
0:10:54 > 0:10:58100 kilometres away, just over there, where I'm pointing, is Tenerife.
0:11:00 > 0:11:05On the coastline, facing Gran Canaria, there is a major collapse
0:11:05 > 0:11:08and that collapse is called Guimar.
0:11:22 > 0:11:26The area where we are now, in the Guimar Valley, in Tenerife,
0:11:26 > 0:11:31it's around about ten kilometres wide along the coast,
0:11:31 > 0:11:36extends several kilometres inland, so it's a big feature.
0:11:37 > 0:11:42Where now there is this broad, flat-floored valley,
0:11:42 > 0:11:47there would have originally been a steep sided volcanic cone.
0:11:49 > 0:11:53So, the area that collapsed is over to our right
0:11:53 > 0:11:59and on the left we can see the lavas that formed the old volcano.
0:12:01 > 0:12:04And between the two we have this enormous cliff.
0:12:05 > 0:12:10But originally that would have been the sidewall of the landslide.
0:12:13 > 0:12:15Over in the distance, from here,
0:12:15 > 0:12:19we can see the tops of the mountains of Gran Canaria,
0:12:19 > 0:12:23round about 100 kilometres away, so it's very easy to imagine
0:12:23 > 0:12:28that the Guimar landside, as it went down into the ocean,
0:12:28 > 0:12:32would have generated a tsunami that spread across the ocean
0:12:32 > 0:12:36to Gran Canaria and produced the tsunami deposits at Agaete.
0:12:40 > 0:12:43This tsunami would drive across the ocean,
0:12:43 > 0:12:46between Tenerife and Gran Canaria,
0:12:46 > 0:12:49and strike in this particular location,
0:12:49 > 0:12:52could easily build up after it hit the coastline,
0:12:52 > 0:12:56travel inland to heights above sea level of hundreds of metres.
0:12:59 > 0:13:03But even Tappin's tsunami would pale alongside the wave
0:13:03 > 0:13:07that would be created by a collapse of the entire mountain flank
0:13:07 > 0:13:09of La Cumbre Vieja.
0:13:11 > 0:13:16Not everyone agrees, but many experts think that such an event
0:13:16 > 0:13:18would have consequences of global proportions.
0:13:21 > 0:13:24It's not surprising that this tiny volcano has become
0:13:24 > 0:13:26so intensely studied.
0:13:31 > 0:13:34This is the story of a scientific model
0:13:34 > 0:13:40of a volcanic collapse of La Palma projected into the near future.
0:13:42 > 0:13:44By using reconstructions...
0:13:45 > 0:13:49Tens of thousands of people are feared dead and hundreds of thousands
0:13:49 > 0:13:53are still missing following the worst natural disaster in history.
0:13:53 > 0:13:58..real archive footage from previous natural disasters
0:13:58 > 0:14:02and graphical representations of what such a wave would do...
0:14:04 > 0:14:08..we can plot out the possible unfolding of events
0:14:08 > 0:14:10that one day could really happen.
0:14:21 > 0:14:23Our scenario begins
0:14:23 > 0:14:26one ordinary day on the island of La Palma itself.
0:14:28 > 0:14:30No-one knows it yet,
0:14:30 > 0:14:34but it's just five days before disaster will strike.
0:14:40 > 0:14:44Seismic monitoring will register a sudden increase in activity.
0:14:44 > 0:14:47Higher! Let's go, come up.
0:14:47 > 0:14:50But, since earthquakes here are common,
0:14:50 > 0:14:52no-one will take too much notice...
0:15:03 > 0:15:06..but then local wildlife will begin to die,
0:15:06 > 0:15:12succumbing to carbon monoxide fumes emanating from the ground.
0:15:12 > 0:15:15A harbinger that something more dangerous is afoot.
0:15:23 > 0:15:26An event that no-one can ignore.
0:15:55 > 0:15:59La Palma's La Cumbre Vieja is erupting once more.
0:16:13 > 0:16:18In one instant, a whole section of the island is dislodged.
0:16:26 > 0:16:33Breaking up as it falls, an entire mountainside plunges into the sea...
0:16:33 > 0:16:36at the speed of an express train.
0:16:46 > 0:16:50We see the landslide first generating an enormous wave.
0:16:59 > 0:17:02Within seconds, the surrounding ocean is distorted.
0:17:06 > 0:17:09At first it forms a huge dome of water...
0:17:11 > 0:17:13..and then a giant wall...
0:17:15 > 0:17:20..on a scale that is almost unimaginable.
0:17:20 > 0:17:21A mega-tsunami.
0:17:24 > 0:17:28That wave could be as much as a kilometre high.
0:17:30 > 0:17:32In terms of the height, you're talking about
0:17:32 > 0:17:35more than two Empire State Buildings on top of one another
0:17:35 > 0:17:38or three of London's Shard piled on top of one another.
0:17:40 > 0:17:42This is an immense mass of water.
0:17:44 > 0:17:48Not just fast, but fast.
0:17:48 > 0:17:51Travelling at up to 800 miles an hour,
0:17:51 > 0:17:54the giant wave surges out in all directions.
0:17:56 > 0:18:01Immediately in its path, the highly populated island of Tenerife,
0:18:01 > 0:18:03less than 100 miles away.
0:18:09 > 0:18:13In less than ten minutes the wave makes landfall.
0:18:17 > 0:18:21Locals and holidaymakers alike do all they can to outrun it.
0:18:51 > 0:18:55Within minutes, the wave has claimed its first victims.
0:18:57 > 0:18:59I don't think there's any doubt that,
0:18:59 > 0:19:03however big the collapse of the west flank of Cumbre Vieja,
0:19:03 > 0:19:06the initial wave will be very catastrophic
0:19:06 > 0:19:07for the islands themselves.
0:19:11 > 0:19:14So, you're talking about thousands of people dead and destruction
0:19:14 > 0:19:17on a scale that we've never seen in this part of the world before.
0:19:22 > 0:19:25With less than ten minutes to react,
0:19:25 > 0:19:29it's hard to see many of the two and a half million locals
0:19:29 > 0:19:33and visitors to the Canary Islands escaping with their lives.
0:19:36 > 0:19:40But even as the wave devastates neighbouring islands,
0:19:40 > 0:19:42La Palma continues to erupt.
0:19:45 > 0:19:48The mountain of La Cumbre Vieja is still collapsing...
0:19:51 > 0:19:55..releasing yet more energy into the sea.
0:20:04 > 0:20:09Our mega-tsunami's journey of destruction has only just begun.
0:20:10 > 0:20:17Within 20 or 30 minutes, all of the waves have spread out from La Palma
0:20:17 > 0:20:23and they've started this long journey out across the Atlantic Ocean.
0:20:27 > 0:20:31There's been no time to raise the alarm.
0:20:31 > 0:20:35Within 60 minutes, 90 metre waves will strike
0:20:35 > 0:20:36the coast of West Africa.
0:20:38 > 0:20:41Over the following hours, these waves will devastate
0:20:41 > 0:20:43the coastlines of Europe.
0:20:50 > 0:20:54While across the Atlantic Ocean, millions of Americans lie sleeping.
0:20:56 > 0:20:59Nothing can stop a wave this size.
0:20:59 > 0:21:05Only landfall and the coastal cities that lie in its path.
0:21:05 > 0:21:07It could be the costliest natural catastrophe
0:21:07 > 0:21:09in the history of our planet.
0:21:22 > 0:21:27While geologists have studied how a landslide tsunami could be caused,
0:21:27 > 0:21:30wave experts like Nils Kerpin are working out
0:21:30 > 0:21:35just how a mega-tsunami would travel once unleashed.
0:21:40 > 0:21:44A miniature Cumbre Vieja
0:21:44 > 0:21:48reveals exactly how fast waves would radiate out from La Palma.
0:21:49 > 0:21:54See that the wave that occurs due to the landslide will propagate
0:21:54 > 0:21:56and encircle around the island.
0:22:05 > 0:22:07Using physical modelling,
0:22:07 > 0:22:11Nils can analyse the very anatomy of the giant wave.
0:22:17 > 0:22:20Here we see the beginning of some landslides
0:22:20 > 0:22:25and we can see air bubbles that are rushing back
0:22:25 > 0:22:28and running up the slope of the remaining island.
0:22:30 > 0:22:33From the very moment it's first formed
0:22:33 > 0:22:37to its height and its speed as it spreads.
0:22:37 > 0:22:40The faster this landslides occurs,
0:22:40 > 0:22:44the more energy will be induced into the water body.
0:22:48 > 0:22:53Fluid science can model not only the wave itself
0:22:53 > 0:22:56but exactly how its journey progresses.
0:22:57 > 0:23:00Northwards towards Europe
0:23:00 > 0:23:03and unchecked across the open Atlantic.
0:23:06 > 0:23:12That science can help us to chart what will happen in our scenario
0:23:12 > 0:23:13in the hours to come.
0:23:25 > 0:23:29It's 80 minutes after the initial landslide
0:23:29 > 0:23:34and, to the east, the wave, still up to 60 metres high,
0:23:34 > 0:23:36is minutes from its first major cities...
0:23:39 > 0:23:43..Casablanca, in Morocco, and its capital Rabat.
0:23:45 > 0:23:47A combined population of six million.
0:23:50 > 0:23:52It is estimated that two thirds of them
0:23:52 > 0:23:55will not survive the wave's impact.
0:24:10 > 0:24:14Only now are the first reports of the unfolding disaster
0:24:14 > 0:24:16beginning to emerge.
0:24:22 > 0:24:27It's likely that, before any news agencies begin to report,
0:24:27 > 0:24:32Twitter, Facebook and mobile calls will carry the first images
0:24:32 > 0:24:34of unfolding disaster to the world.
0:24:39 > 0:24:42In London, the Prime Minister becomes aware of events.
0:24:43 > 0:24:47When a disaster happens that dominates everything,
0:24:47 > 0:24:49the whole diary's cleared.
0:24:51 > 0:24:55The PM summons the relevant government departments
0:24:55 > 0:24:58and representatives of the emergency services
0:24:58 > 0:25:00to the Cobra response room.
0:25:00 > 0:25:05Cobra's that kind of high-tech room with lots of links to police,
0:25:05 > 0:25:08the fire services, etc, round the country.
0:25:10 > 0:25:13But they have little time to plan.
0:25:19 > 0:25:24Just 30 minutes after Casablanca, the wave reaches Europe.
0:25:32 > 0:25:35It is still the height of a two-storey house.
0:25:37 > 0:25:41The coastal capital of Lisbon is devastated.
0:25:55 > 0:25:58Back in Westminster, the Cobra meeting room
0:25:58 > 0:26:01is now a centre of intense activity.
0:26:03 > 0:26:05So, the first thing we want to know
0:26:05 > 0:26:08is, "Just how big is this? What's actually happening?"
0:26:11 > 0:26:14Often, if you've got a TV screen on,
0:26:14 > 0:26:18you'll know as much as the person in the centre of Whitehall.
0:26:20 > 0:26:23As likely as not they'll have Sky and BBC 24-hour,
0:26:23 > 0:26:26and they'd be following Twitter and social media.
0:26:27 > 0:26:31There is always, always a period where there is a kind of fog of uncertainty.
0:26:31 > 0:26:36I think the key point is to alert the emergency services,
0:26:36 > 0:26:39so that they are prepared for it to happen.
0:26:44 > 0:26:49After hitting Lisbon, the emergency services have just three hours
0:26:49 > 0:26:51before the wave strikes Britain.
0:26:53 > 0:26:58The Environment Agency issues flood warnings to the south coast.
0:27:00 > 0:27:05Fire, ambulance and rescue units are put on standby.
0:27:07 > 0:27:11Police clear the streets of southern coastal towns,
0:27:11 > 0:27:14evacuating schools and vulnerable communities.
0:27:20 > 0:27:25Back in Whitehall, the Government has two work out what to say
0:27:25 > 0:27:29and how to deal with increasing public panic
0:27:29 > 0:27:32as awareness of the scale of unfolding events spreads.
0:27:34 > 0:27:38A giant tsunami is spreading throughout the Atlantic basin.
0:27:38 > 0:27:41Waves of up to 40 metres high have already devastated
0:27:41 > 0:27:44the coasts of Portugal, North Africa and Spain.
0:27:44 > 0:27:49Scientists estimate that the wave is travelling at approximately 500mph.
0:27:49 > 0:27:51It's expected to move across the Atlantic...
0:27:51 > 0:27:54You're still building up information as well as trying to move people.
0:27:54 > 0:27:56That'll be the time that the media are saying,
0:27:56 > 0:27:58"What are you doing about it? What's happening?"
0:27:58 > 0:28:01The key test of the Government will be to show they're responding,
0:28:01 > 0:28:03to outline the measures they're taking.
0:28:03 > 0:28:05But the measures they're taking
0:28:05 > 0:28:07are in the time when they really don't know how serious it is.
0:28:09 > 0:28:13Just three hours after the first UK warnings,
0:28:13 > 0:28:18a wave up to 25 metres high makes its first landfall in Britain...
0:28:20 > 0:28:22..on Cornwall.
0:28:36 > 0:28:39In the immediate aftermath, say two or three hours after it's hit,
0:28:39 > 0:28:41they'll still be confusion.
0:28:41 > 0:28:44I mean, we're probably talking about a very, very wide area of hundreds of miles.
0:28:44 > 0:28:48So, finding out what's happening in a cove in Devon or Cornwall,
0:28:48 > 0:28:50I mean, you know, how is that going to get back?
0:28:50 > 0:28:52I mean, you could well have communities wiped out.
0:29:08 > 0:29:12We can get some idea of the impact of a seven to ten metre wave,
0:29:12 > 0:29:13on the UK south coast,
0:29:13 > 0:29:17by looking at what happened in the Indian Ocean in 2004,
0:29:17 > 0:29:19in places like Sri Lanka and Thailand.
0:29:21 > 0:29:23The level of destruction was immense
0:29:23 > 0:29:26and the death toll was in the tens of thousands.
0:29:29 > 0:29:32You could say that the population of the south coast of the UK
0:29:32 > 0:29:34is probably quite a bit higher,
0:29:34 > 0:29:38so that sort of wave would be immensely destructive in the UK.
0:29:40 > 0:29:45From Cornwall, the wave surges through into the Irish Sea
0:29:45 > 0:29:47and through the English Channel,
0:29:47 > 0:29:50engulfing much of Britain's south coast.
0:29:51 > 0:29:55The aspect that makes a tsunami so devastating is its wavelength
0:29:55 > 0:29:56and how long it is.
0:30:02 > 0:30:05A storm wave might be ten, 20, 30 metres long, 40 metres long,
0:30:05 > 0:30:0750 metres long.
0:30:07 > 0:30:09In the case of a tsunami,
0:30:09 > 0:30:12we have a wave that is 200 or 300 kilometres long.
0:30:14 > 0:30:19Unlike a storm wave, a tsunami just keeps on coming -
0:30:19 > 0:30:21mile after mile of it.
0:30:24 > 0:30:27Seawater floods our southern cities
0:30:27 > 0:30:32and penetrates low-lying farmland for miles inland.
0:30:36 > 0:30:40It not only runs up the coastline and inundates the land,
0:30:40 > 0:30:44but it continues to flow inland, as if it's a river flowing over
0:30:44 > 0:30:49the land and scouring out, and removing things in its path.
0:30:49 > 0:30:51So, it's the inundation, it's the wavelength,
0:30:51 > 0:30:54that actually makes these events so dangerous.
0:30:57 > 0:31:01Models differ on what the wave might do to our southern cities
0:31:01 > 0:31:03as it works its way east.
0:31:04 > 0:31:08Towns such as Brighton would probably survive,
0:31:08 > 0:31:10but would suffer serious disruption.
0:31:29 > 0:31:33In our scenario, London, our capital,
0:31:33 > 0:31:36tucked in from the North Sea, is safely sheltered.
0:31:40 > 0:31:46Britain, it seems, will survive the worst calamities seen elsewhere.
0:31:51 > 0:31:56The wave, however, as well as travelling east to Africa
0:31:56 > 0:32:01and north to Europe is also heading west, across the Atlantic.
0:32:04 > 0:32:09And there is a whole new nation is waking up - America.
0:32:09 > 0:32:13'Good morning, New York. It's a beautiful day out there in the city
0:32:13 > 0:32:16'but here's a word of advice, enjoy it while you can.
0:32:16 > 0:32:19'The weathermen says there's going to be some rain this afternoon
0:32:19 > 0:32:23'and temperatures could drop dramatically by the end of the day.'
0:32:23 > 0:32:28It's 7am. As the tsunami is devastating southern Britain,
0:32:28 > 0:32:31it's three hours away from New York.
0:32:39 > 0:32:471,500 miles off the coast, the wave hurtles west at incredible speed.
0:32:50 > 0:32:53The deeper the water, the faster the wave moves.
0:32:53 > 0:32:55So, in five kilometres of water
0:32:55 > 0:32:58the wave will move at 800 kilometres an hour.
0:32:58 > 0:33:01It's travelling at the speed of a jet plane.
0:33:01 > 0:33:05Bear in mind, it's not the water that is moving.
0:33:05 > 0:33:08So, you can't imagine water moving at 800 kilometres an hour,
0:33:08 > 0:33:10it's the energy of the wave.
0:33:10 > 0:33:13The particles of water are pushing against each other
0:33:13 > 0:33:16and so, if you like, each is knocking against the next
0:33:16 > 0:33:19and it's moving the energy across the oceans.
0:33:23 > 0:33:27For evidence of how tsunami waves can travel between continents,
0:33:27 > 0:33:31scientists, once again, only need to look to the past.
0:33:32 > 0:33:35In particular, evidence of
0:33:35 > 0:33:40an earthquake generated tsunami that began in Chile in 1960.
0:33:42 > 0:33:46'Devastation untold, a death toll close on 5,000,
0:33:46 > 0:33:50'is part of the reckoning that staggers Chile. In Concepcion, city of...'
0:33:50 > 0:33:53The earthquake itself caused lots of damage, significant damage
0:33:53 > 0:33:57but it also created a very large tsunami.
0:33:57 > 0:34:00That tsunami did cause damage in Chile itself,
0:34:00 > 0:34:03but what was interesting about that one was that the damage it caused
0:34:03 > 0:34:06further afield was also significant.
0:34:06 > 0:34:09'Incredibly, Hawaii, 6,000 miles away in mid-Pacific,
0:34:09 > 0:34:12'was struck by four gigantic tidal waves.
0:34:12 > 0:34:16'On surged the terrifying walls of water as far as the Japanese coast
0:34:16 > 0:34:17'9,000 miles from Chile.'
0:34:20 > 0:34:24And that really brought home the fact that a tsunami happening
0:34:24 > 0:34:27one side of the ocean can have a dramatic impact
0:34:27 > 0:34:28the other side of the ocean.
0:34:31 > 0:34:35The wrath of volcanoes and earthquakes is all too evident,
0:34:35 > 0:34:38but often their violence is geographically limited.
0:34:39 > 0:34:43But tsunamis are different.
0:34:44 > 0:34:49Fluid dynamics means that the ocean itself can carry the energy
0:34:49 > 0:34:55of a tsunami over thousands of miles and in all directions.
0:35:03 > 0:35:0830 minutes after the northern face of the wave first struck Cornwall,
0:35:08 > 0:35:13its western edge is just 1,200 miles from a whole new nation.
0:35:15 > 0:35:18In the US, 40 million people
0:35:18 > 0:35:20live within 40 kilometres of the coastline.
0:35:20 > 0:35:23And of those 40 million people,
0:35:23 > 0:35:25something like 30 million of them
0:35:25 > 0:35:30live within ten metres, vertically, of the shoreline.
0:35:32 > 0:35:35If you're looking at these extreme events, like a tsunami,
0:35:35 > 0:35:39that can put ten, 20, 30 metre waves at the shoreline,
0:35:39 > 0:35:43that's an incredibly vulnerable population.
0:35:43 > 0:35:49Atlantic City, Washington, Boston...
0:35:49 > 0:35:51and New York.
0:35:55 > 0:35:59Major cities along the coast all lie directly in its path.
0:36:03 > 0:36:07- ALARM BEEPING - 'Short period alarm.'
0:36:07 > 0:36:09'Short period alarm.'
0:36:09 > 0:36:12America is equipped with systems
0:36:12 > 0:36:15capable of detecting an inbound tsunami.
0:36:15 > 0:36:18The first is a network of seismometers,
0:36:18 > 0:36:20located around the world,
0:36:20 > 0:36:25which feed real-time data to a monitoring station in Alaska.
0:36:25 > 0:36:28This shows the signal from all the different seismometers
0:36:28 > 0:36:32that come in to the centre. Coming in in what we call real-time.
0:36:32 > 0:36:35If there's anything that significant, it will trigger an alarm
0:36:35 > 0:36:38and that will bring the guys in to take a look at the event.
0:36:39 > 0:36:45But this system is designed to detect tsunamis generated by earthquakes.
0:36:45 > 0:36:47Not a distant landslide
0:36:47 > 0:36:51like the collapse of La Cumbre Vieja on La Palma.
0:36:51 > 0:36:54Landslide generated tsunamis are very hard for us to respond to.
0:36:54 > 0:36:58They do not show up on our seismic networks in the same way that earthquakes do.
0:36:58 > 0:37:00Much, much more challenging.
0:37:02 > 0:37:06A second line of defence is a network of deep ocean sensors
0:37:06 > 0:37:11called DARTs, designed to detect changes in water pressure
0:37:11 > 0:37:13caused by passing waves.
0:37:13 > 0:37:16If there was a tsunami generated in the Canary Islands,
0:37:16 > 0:37:21we would see impacts on our DART in the central Atlantic Ocean.
0:37:23 > 0:37:26The DART system would raise the alarm,
0:37:26 > 0:37:30but just three to four hours before the waves hit the coast.
0:37:43 > 0:37:48The likelihood, though, is that, for all their sophistication,
0:37:48 > 0:37:51these technological detection measures would do well
0:37:51 > 0:37:55to beat the speed of reports coming through social media.
0:37:58 > 0:38:04For America, news of the mega-tsunami's impact in Africa and Europe
0:38:04 > 0:38:07would throw their own fate into sharp relief.
0:38:12 > 0:38:19New York City is 8.4 million people who live on 302 square miles.
0:38:19 > 0:38:21That is three islands and a peninsula,
0:38:21 > 0:38:24mostly about 50 feet above the waterline.
0:38:26 > 0:38:29It is a world-class city with enormous strengths
0:38:29 > 0:38:32and also significant vulnerabilities.
0:38:34 > 0:38:36An example is the island of Manhattan,
0:38:36 > 0:38:40which has a population of about 1.5 million.
0:38:40 > 0:38:42That population doubles every business day
0:38:42 > 0:38:44to about three million people.
0:38:47 > 0:38:51For the city authorities, it's a question of how many people
0:38:51 > 0:38:53you might be able to save.
0:38:57 > 0:39:01New York's Office of Emergency Management is responsible
0:39:01 > 0:39:04for coordinating the response to any natural disaster.
0:39:06 > 0:39:13We have spent the last ten years analysing the roadway network
0:39:13 > 0:39:18and the mass transit network, and the population,
0:39:18 > 0:39:24and determining how long it would take to evacuate.
0:39:27 > 0:39:31The city's rail network would be the primary means of escape.
0:39:36 > 0:39:40And yet, for all the evacuation plans in place,
0:39:40 > 0:39:41there's a terrible irony.
0:39:43 > 0:39:47Even in the apparent knowledge that disaster is imminent,
0:39:47 > 0:39:52studies have shown that whole populations can go into denial.
0:39:52 > 0:39:56Refusing to accept that the danger is real.
0:39:59 > 0:40:04So, if we can get people to think, "This IS going to happen to me,
0:40:04 > 0:40:06"I AM at risk, my family is at risk,"
0:40:06 > 0:40:10then we can get them to move. But the reality is that up to half
0:40:10 > 0:40:13the people won't move, no matter what we say to them.
0:40:13 > 0:40:16They don't believe that it's going to happen.
0:40:24 > 0:40:26For many typical New Yorkers,
0:40:26 > 0:40:29with the wave heading straight towards them,
0:40:29 > 0:40:33this is just another day in the Big Apple.
0:40:54 > 0:41:00Meanwhile, as American city dwellers try to decide whether to go or stay,
0:41:00 > 0:41:03the wave is about to hit the islands of the Caribbean.
0:41:06 > 0:41:11Here, it's another ordinary day of perfect sun and sea.
0:41:11 > 0:41:13But, across all the islands,
0:41:13 > 0:41:1840 million people live predominantly in coastal towns.
0:41:28 > 0:41:32The Caribbean would be absolutely devastated by this kind of wave.
0:41:32 > 0:41:37We would have ten to 20 metre waves sweeping across many of the islands.
0:41:38 > 0:41:42Bermuda, the wave would probably sweep entirely over the island.
0:41:42 > 0:41:44There would be nothing left.
0:41:44 > 0:41:47It would actually be stripped to the foundations.
0:41:47 > 0:41:51A lot of the islands are volcanic, so they have very steep shorelines.
0:41:51 > 0:41:53If you could go half a mile inland you would be out of the way
0:41:53 > 0:41:56but how do you get half a mile inland?
0:41:56 > 0:41:58The road infrastructure parallels the coastline,
0:41:58 > 0:42:00so you would literally have to run on foot
0:42:00 > 0:42:02to get out of the wave in many areas.
0:42:02 > 0:42:06So it's an extremely dangerous event for the Caribbean.
0:42:11 > 0:42:14With the wave now just minutes away from both the financial
0:42:14 > 0:42:19and political centres of the world's greatest superpower,
0:42:19 > 0:42:22most experts believe that the major eastern cities
0:42:22 > 0:42:24would still be packed.
0:42:28 > 0:42:32But now even hardened New Yorkers have to take notice.
0:42:34 > 0:42:39Evacuation plans have been activated, but it's chaos.
0:42:39 > 0:42:42You either go up high and risk becoming marooned
0:42:42 > 0:42:46or take underground road and rail tunnels out of Manhattan,
0:42:46 > 0:42:50and face the possibility of a gridlocked tomb.
0:42:50 > 0:42:54By the time the warning network's been up, it's here.
0:42:54 > 0:42:58So, we might have two or three hours notice at best.
0:42:59 > 0:43:02The question is, what can you do in two or three hours?
0:43:02 > 0:43:04And the answer is not much.
0:43:04 > 0:43:08The ocean wave is now only 12 metres high,
0:43:08 > 0:43:14but, as it approaches New York, it rears up again, becoming a monster.
0:43:16 > 0:43:20The back of the wave is still moving at, say, 500 miles an hour.
0:43:20 > 0:43:23The front of the wave is moving at, maybe, 40 miles an hour.
0:43:23 > 0:43:25And so the wave piles up,
0:43:25 > 0:43:28and that's where we go from a wave that is maybe a foot,
0:43:28 > 0:43:3230 centimetres high, to a wave that can suddenly become 50 metres high.
0:43:32 > 0:43:35And that's where the destruction occurs.
0:43:38 > 0:43:44No-one knows exactly how great a mega-tsunami's impact would be,
0:43:44 > 0:43:48but science points to one of mankind's greatest cities
0:43:48 > 0:43:52being humbled by the power of nature.
0:43:55 > 0:43:59What's worse is that studies have revealed that the landslide
0:43:59 > 0:44:03will result in not one wave but several.
0:44:06 > 0:44:09And the first will not be the biggest.
0:44:11 > 0:44:13People think of it as being one tsunami.
0:44:13 > 0:44:16There would be as many as ten waves sweeping across the coast.
0:44:18 > 0:44:21The first wave would be maybe eight to ten metres.
0:44:27 > 0:44:30The second wave would be as much as 25.
0:45:28 > 0:45:32Only 12 hours earlier, it was just another normal day.
0:45:33 > 0:45:38Now a geological collapse of a small volcano on a tiny island
0:45:38 > 0:45:44has changed tens of millions of lives on three separate continents.
0:45:46 > 0:45:48Tens of thousands of people are feared dead
0:45:48 > 0:45:51and hundreds of thousands are still missing,
0:45:51 > 0:45:53following the worst natural disaster in history.
0:45:57 > 0:46:01By the time our tsunami strikes New York,
0:46:01 > 0:46:05in Britain a nation is already coming to terms
0:46:05 > 0:46:07with widespread loss.
0:46:07 > 0:46:10The authorities say they are doing everything they can
0:46:10 > 0:46:12and have appealed for calm.
0:46:12 > 0:46:15A state of emergency has been declared.
0:46:20 > 0:46:24But this tsunami itself would only be the beginning
0:46:24 > 0:46:27of a whole new chain of events.
0:46:31 > 0:46:35Disaster planners know that, following any catastrophe,
0:46:35 > 0:46:38the biggest dangers come in the aftermath.
0:46:39 > 0:46:42Rescuing the injured and identifying the dead...
0:46:45 > 0:46:49..caring for a traumatised population and preventing disease...
0:46:51 > 0:46:56..retaining law and order and the reins of civilisation.
0:47:06 > 0:47:11In America, where our mega-tsunami has struck at the very heart
0:47:11 > 0:47:14of the world's political and economic capitals,
0:47:14 > 0:47:17the challenges are greatest of all.
0:47:20 > 0:47:22When you talk about Manhattan,
0:47:22 > 0:47:27virtually the entirety of Manhattan is below ten metres above sea level.
0:47:27 > 0:47:30So, if you were in the New York City area, hopefully,
0:47:30 > 0:47:34you evacuated up and didn't try to go out...
0:47:34 > 0:47:37and you'd be trapped, basically, while the water receded.
0:47:40 > 0:47:44You have this initial impact of the water, which is heavy,
0:47:44 > 0:47:47but as it recedes you've got the same amount of water going back
0:47:47 > 0:47:50into the ocean, taking with it a lot of debris.
0:47:50 > 0:47:54It's taking trees, it's taking buildings, it's taking cars
0:47:54 > 0:47:59and, so, all of a sudden, you have this water with a load
0:47:59 > 0:48:05of battering rams going back through the population that it's just hit.
0:48:05 > 0:48:08And as much damage is caused by the receding wave
0:48:08 > 0:48:11as is often caused by that initial wave.
0:48:13 > 0:48:16Taking the wave's progress to its final conclusion
0:48:16 > 0:48:20and, with the help of experts in disaster planning,
0:48:20 > 0:48:23we are able to continue our own scenario.
0:48:27 > 0:48:31It takes days before calm finally returns to the sea.
0:48:33 > 0:48:38Only now is the true scale of destruction becoming clear.
0:48:42 > 0:48:47New York, Boston, Washington, Miami -
0:48:47 > 0:48:52entire cities have been destroyed.
0:48:52 > 0:48:55The number of casualties is really hard to get at
0:48:55 > 0:48:57in something like this.
0:48:57 > 0:49:02For the 25 metre scenario, with maybe three to four hours of warning,
0:49:02 > 0:49:05we came up with roughly 4.5 million casualties.
0:49:13 > 0:49:17After the wave, those living, like in Japan,
0:49:17 > 0:49:20face a devastated homeland.
0:49:20 > 0:49:23You'd be left with an unimaginable landscape.
0:49:23 > 0:49:26Smaller structures would be destroyed and scattered,
0:49:26 > 0:49:30so the debris would be piled probably five, six metres high in the streets.
0:49:35 > 0:49:39Debris sits like a blanket across the city
0:49:39 > 0:49:43and it prevents us from getting ambulances to people who need them,
0:49:43 > 0:49:48and getting fire trucks to fires, and getting people to grocery stores
0:49:48 > 0:49:52to get food, and so, debris is our biggest and worst problem.
0:49:54 > 0:49:57The doctors, physicians, emergency responders,
0:49:57 > 0:50:00they're going to have enough trouble dealing with things
0:50:00 > 0:50:03they can see within 100 yards of their facility,
0:50:03 > 0:50:06much less being able to actually go on emergency calls.
0:50:06 > 0:50:09So, you can pretty much expect anyone that is injured
0:50:09 > 0:50:12is going to be on their own for at least a week.
0:50:12 > 0:50:15If it's any kind of a serious injury, without medical attention,
0:50:15 > 0:50:16they are likely to expire.
0:50:21 > 0:50:27Dealing with death on such a scale becomes a massive priority.
0:50:27 > 0:50:30Kenyon International Emergency Services is a private company
0:50:30 > 0:50:32that responds to disasters.
0:50:32 > 0:50:36Disasters that typically involve the loss of human life.
0:50:37 > 0:50:42We deal with mass fatalities that are catastrophic -
0:50:42 > 0:50:44a quarter of a million dead.
0:50:50 > 0:50:54This is a refrigeration unit, a portable refrigeration cabinet,
0:50:54 > 0:50:58of which we have several that we use to hold the deceased.
0:51:01 > 0:51:04The purpose of the morgue is where we examine the bodies
0:51:04 > 0:51:08and collect that picture that we're going to use to identify them.
0:51:08 > 0:51:12So, it's where the personal effects are collected...
0:51:12 > 0:51:16where we take the fingerprints, get the dental x-ray,
0:51:16 > 0:51:20make measurements of the body, record tattoos and scars.
0:51:20 > 0:51:23In the case of a natural disaster,
0:51:23 > 0:51:25where it's going to be some time before we can return the body,
0:51:25 > 0:51:30doing the embalming, the restoration, and the preservation of the body.
0:51:30 > 0:51:35So that it can be returned in a sanitary condition to the families.
0:51:40 > 0:51:43But even if emergency facilities like these could be set up,
0:51:43 > 0:51:46they would soon be overwhelmed.
0:51:46 > 0:51:49It's possible that millions of dead
0:51:49 > 0:51:53would be left to decay where they died
0:51:53 > 0:51:56and that brings with it yet another threat.
0:51:59 > 0:52:04It would be a horrific mix of debris and, unfortunately,
0:52:04 > 0:52:06human remains, animal remains.
0:52:08 > 0:52:10So, you can imagine, after a few hours,
0:52:10 > 0:52:13you would have a biological nightmare.
0:52:16 > 0:52:21Lack of shelter, food, water,
0:52:21 > 0:52:25and diseases like dysentery all become killers.
0:52:30 > 0:52:36We have identified 500 different locations
0:52:36 > 0:52:41that we could activate as emergency shelters.
0:52:42 > 0:52:44Those are primarily public schools
0:52:44 > 0:52:48and some of our city university buildings and facilities.
0:52:48 > 0:52:52The capacity of the system is 600,000 people.
0:52:52 > 0:52:56We don't look forward to a job
0:52:56 > 0:53:00where we would have to shelter 600,000 people,
0:53:00 > 0:53:04but that is the capacity of the system today.
0:53:08 > 0:53:13It's simply impossible to plan for such a scale of disaster.
0:53:13 > 0:53:19All these provisions will feed only 70,000 people for seven days.
0:53:19 > 0:53:23Just a tiny fraction of the possible numbers of displaced survivors
0:53:23 > 0:53:26in Manhattan alone.
0:53:30 > 0:53:34Our mega-tsunami has triggered not only death and destruction
0:53:34 > 0:53:36in the American East,
0:53:36 > 0:53:41but a humanitarian crisis that could affect the entire nation.
0:53:42 > 0:53:47Think of losing every single east coast shipping port.
0:53:47 > 0:53:51That's essentially what we're talking about with a mega-tsunami.
0:53:53 > 0:53:56If you lose those ports, you have a huge problem,
0:53:56 > 0:53:58believe it or not, into the Midwest of the US.
0:53:58 > 0:54:03All the way to the Mississippi River because a lot of that infrastructure, those rail hubs,
0:54:03 > 0:54:06come right to the coast.
0:54:06 > 0:54:12So, even if people weren't directly impacted by the tsunami itself,
0:54:12 > 0:54:16they wouldn't have food coming to their supermarkets.
0:54:16 > 0:54:18Far inland, many hundreds of miles
0:54:18 > 0:54:21from the direct effects of the mega-tsunami,
0:54:21 > 0:54:23there could be mass food shortages.
0:54:25 > 0:54:29Most cities only have a two or three day supply of food,
0:54:29 > 0:54:31so you think about cities like Atlanta,
0:54:31 > 0:54:34you think about Memphis, you think about those inland areas
0:54:34 > 0:54:38that get a lot of their material coming from ports on the east coast
0:54:38 > 0:54:42and that's suddenly gone for years, perhaps, to recover -
0:54:42 > 0:54:44that's an enormous problem.
0:54:45 > 0:54:48And, ultimately, the scale of disaster
0:54:48 > 0:54:51won't just be measured in lives lost.
0:54:53 > 0:54:54No-one can be sure,
0:54:54 > 0:55:00but a mega-tsunami could deliver a financial shock so great
0:55:00 > 0:55:03that it's impact could change the global economy,
0:55:03 > 0:55:08politics and the balance of East-West power, perhaps forever.
0:55:08 > 0:55:10You think about how much disruption was caused
0:55:10 > 0:55:13by September 11, 2001, attacks
0:55:13 > 0:55:16and how much that disrupted the world economy.
0:55:16 > 0:55:18Well, they were back up and running four days later.
0:55:18 > 0:55:23Imagine if they weren't able to be back up and running in 40 days or 40 months.
0:55:26 > 0:55:29It could be that the world's economy would recover,
0:55:29 > 0:55:33as capitalists moved electronic money to safer havens.
0:55:35 > 0:55:37There is some evidence,
0:55:37 > 0:55:41as was the case with the Kobe earthquake of 1995,
0:55:41 > 0:55:45that's natural disasters can even trigger investment and renewal.
0:55:47 > 0:55:52But it's hard to imagine the fragile global economy bouncing back
0:55:52 > 0:55:55from such devastation as this.
0:55:55 > 0:55:58The truth is, no-one really knows...
0:55:59 > 0:56:03..and, hopefully, given that landslide events
0:56:03 > 0:56:05are, fortunately, rare,
0:56:05 > 0:56:08no-one soon will get the chance to find out.
0:56:15 > 0:56:19In the long-term, we know these ocean island collapses occur.
0:56:19 > 0:56:23Around the world, there may be one of these enormous events
0:56:23 > 0:56:27maybe once every 20,000 years, maybe only once every 50,000 years.
0:56:29 > 0:56:31We can't say when the collapse is going to occur...
0:56:34 > 0:56:36..but the problem with the Cumbre Vieja
0:56:36 > 0:56:40is that it seems to already be close to failure.
0:56:43 > 0:56:48So, the crucial question is not a matter of "if" but of "when".
0:57:02 > 0:57:06We aren't prepared in the UK, for a tsunami.
0:57:06 > 0:57:10No measures have been put in place to mitigate tsunamis.
0:57:10 > 0:57:13Now, I think we need to learn from events, like Japan,
0:57:13 > 0:57:15that that really isn't the best policy.
0:57:17 > 0:57:21I think the question, "Are you prepared for a tsunami?"
0:57:21 > 0:57:23is almost the wrong question because, to an extent,
0:57:23 > 0:57:27you can't prepare for them, as Japan very clearly illustrated.
0:57:27 > 0:57:29The Japanese were ready,
0:57:29 > 0:57:34they prepared themselves for the potential impact of a tsunami wave.
0:57:34 > 0:57:37Those defences were still inadequate.
0:57:39 > 0:57:41The consequences were 15,000 dead
0:57:41 > 0:57:44and the costliest natural catastrophe in the history of our planet.
0:57:51 > 0:57:55Can we prevent the same thing that happened in Japan happening in Britain?
0:57:55 > 0:58:00No. Japan is probably one of the best equipped countries in the world
0:58:00 > 0:58:03in defending itself against tsunamis.
0:58:03 > 0:58:07If they can't get it right...we can't.
0:58:07 > 0:58:10And it's not a question of them getting it wrong,
0:58:10 > 0:58:12it's a question of there's a limit of what we can do
0:58:12 > 0:58:14against the forces of nature.
0:58:42 > 0:58:45Subtitles by Red Bee Media Ltd