0:00:02 > 0:00:04On today's Fierce Earth...
0:00:04 > 0:00:07When the ground lets us down.
0:00:07 > 0:00:08Danger from above!
0:00:08 > 0:00:11The island being eaten away by the sea.
0:00:13 > 0:00:15Danger from below.
0:00:15 > 0:00:17Exploring the secret world of the sinkhole.
0:00:20 > 0:00:22Danger all around!
0:00:25 > 0:00:27Look out for the landslide!
0:00:28 > 0:00:32What happens when the ground shakes, the seas rise up
0:00:32 > 0:00:35and the air tears itself apart?
0:00:35 > 0:00:37The Fierce Earth team move in,
0:00:37 > 0:00:40taking on the most powerful forces on the planet.
0:00:56 > 0:00:58Get ready for Fierce Earth -
0:00:58 > 0:01:00the Earth and how to survive it.
0:01:04 > 0:01:08Rock, earth, debris...
0:01:08 > 0:01:11a landslide is any or all of these things,
0:01:11 > 0:01:13moving down a slope, en masse.
0:01:13 > 0:01:16Landslides can be big, they can be small.
0:01:16 > 0:01:20They can happen slowly or be over in seconds.
0:01:20 > 0:01:22One thing is for certain, though -
0:01:22 > 0:01:27if you're above, or if you're below, landslides can mean big trouble.
0:01:27 > 0:01:30Houses, roads, people - they're all at risk
0:01:30 > 0:01:34when the solid ground we take for granted gives way.
0:01:37 > 0:01:38Today, we're going to find out
0:01:38 > 0:01:42exactly why the earth can suddenly move,
0:01:42 > 0:01:45and how humans survive in the shadow of the landslide.
0:01:52 > 0:01:55There are four main types of landslides.
0:01:55 > 0:02:00The fall, where material breaks off from a cliff, or a steep slope,
0:02:00 > 0:02:01and tumbles down.
0:02:03 > 0:02:06The topple, where a big chunk falls forward
0:02:06 > 0:02:08from the top of a slope.
0:02:11 > 0:02:16Next, we have the slide, a mass of material slides down the slope
0:02:16 > 0:02:18along a clean break.
0:02:20 > 0:02:22And, finally, the flow.
0:02:22 > 0:02:27Material flows down the slope as a liquid, like mudflows.
0:02:28 > 0:02:30Landslides occur all over the world
0:02:30 > 0:02:35and are often triggered as a result of earthquakes or volcanoes.
0:02:35 > 0:02:38But there is one country with no volcanoes
0:02:38 > 0:02:42and few earthquakes that is still at risk from landslides,
0:02:42 > 0:02:46a country usually spared the worst of the Fierce Earth.
0:02:46 > 0:02:49And that country is the United Kingdom.
0:02:56 > 0:02:58Whoo!
0:03:01 > 0:03:05The UK is under attack from all sides by the sea.
0:03:05 > 0:03:07Lashed by the wind from the Atlantic,
0:03:07 > 0:03:10enduring snow and ice every winter.
0:03:10 > 0:03:13And let's not forget the rain.
0:03:13 > 0:03:17All these things create erosion, one of the major causes of landslides.
0:03:17 > 0:03:21In the UK, they tend to be slow moving and rarely cause injuries,
0:03:21 > 0:03:25but landslides can still be seriously destructive.
0:03:25 > 0:03:29And there's one little island here that really takes a battering.
0:03:31 > 0:03:34This is the Isle of Wight in the English Channel.
0:03:34 > 0:03:36It's like the UK in miniature,
0:03:36 > 0:03:39surrounded by 100 kilometres of coastline.
0:03:39 > 0:03:43No-one lives very far from the water
0:03:43 > 0:03:46and because of that, landslides have become a part of life.
0:03:50 > 0:03:53The Needles are the Isle of Wight's most famous landmark -
0:03:53 > 0:03:57a series of chalk stacks rising out of the sea.
0:03:57 > 0:04:00The Needles are absolutely stunning,
0:04:00 > 0:04:03but they're the clearest example
0:04:03 > 0:04:06that erosion is slowly shrinking the island
0:04:06 > 0:04:07and causing landslides.
0:04:10 > 0:04:13Once upon a time, the Needles would have been arches
0:04:13 > 0:04:16and, before that, cliffs.
0:04:16 > 0:04:19Like the rest of the UK, the coastline here is always changing.
0:04:22 > 0:04:24Roads might have to be re-routed,
0:04:24 > 0:04:28houses abandoned and demolished before they fall into the sea,
0:04:28 > 0:04:32but it's the same story across much of the UK.
0:04:32 > 0:04:35So what's going on?
0:04:35 > 0:04:37Coastal erosion is what's going on.
0:04:37 > 0:04:41The sea attacking the land and it never gives up.
0:04:45 > 0:04:48The sea is moving constantly, isn't it?
0:04:48 > 0:04:52Every day, every night, wearing away at the cliffs
0:04:52 > 0:04:53that make up the coast.
0:04:55 > 0:04:58As bits fall off the cliff, they're washed back again by the waves,
0:04:58 > 0:05:02acting like giant sandpaper, scouring away.
0:05:03 > 0:05:06The waves undercut the rock at sea level,
0:05:06 > 0:05:09and the land above gives way - a landslide.
0:05:11 > 0:05:15They say an Englishman's home is his castle,
0:05:15 > 0:05:17but he'd better watch out where he builds it.
0:05:25 > 0:05:29The softer the rock, the more at risk it is from erosion,
0:05:29 > 0:05:32and there's a lot of soft, white chalk on the Isle of Wight.
0:05:32 > 0:05:36But tougher rock is no match for water, either,
0:05:36 > 0:05:40and erosion causes rock falls all over the UK.
0:05:40 > 0:05:42Leo is in Scotland to find out how.
0:05:44 > 0:05:47The River Spean in the West Highlands.
0:05:47 > 0:05:51It wends its way through spectacular gorges cut through solid rock.
0:05:53 > 0:05:55Gorges cut by the power of water,
0:05:55 > 0:05:58but not just this bit of water, that kind of water.
0:06:02 > 0:06:04My kind of water.
0:06:05 > 0:06:08Flowing water erosion has caused rock falls
0:06:08 > 0:06:12and landslips that have left the river bed littered with debris -
0:06:12 > 0:06:15anything from small stones to huge boulders.
0:06:15 > 0:06:16They churn up the water
0:06:16 > 0:06:19and create some of the most spectacular rapids in the UK.
0:06:19 > 0:06:23And I'm going to take on those rapids in this...
0:06:23 > 0:06:24Here we go.
0:06:24 > 0:06:25..a River Bug.
0:06:25 > 0:06:28This tiny, white-water raft will let me really experience
0:06:28 > 0:06:32the fierce power of the water as it races through the rock.
0:06:33 > 0:06:34Rapids are dangerous,
0:06:34 > 0:06:37so I'll be watched over every splash of the way
0:06:37 > 0:06:39by white-water specialist Joe.
0:06:40 > 0:06:41So it's quite a rocky river.
0:06:41 > 0:06:44What happens if I'm going to crash into a big rock?
0:06:44 > 0:06:46If you're going backwards, that's fine,
0:06:46 > 0:06:50this big air packet behind you, this air bag, acts a bit like a cushion.
0:06:50 > 0:06:54If you're going forward, however, you get your legs out in front
0:06:54 > 0:06:55but keep your knees soft.
0:06:55 > 0:06:58- So you can fend yourself off? - Exactly.
0:06:58 > 0:07:00If you come across a boulder, just push off with your feet
0:07:00 > 0:07:04and push yourself back into the flow, where the water's nice and deep.
0:07:04 > 0:07:07- Ready to rock'n'roll? - Let's do this!- Excellent.
0:07:11 > 0:07:14I'm going to have to get good at this fast, but, remember,
0:07:14 > 0:07:18I've had training from an expert. Never attempt this on your own.
0:07:29 > 0:07:30Agh!
0:07:32 > 0:07:34Ah!
0:07:34 > 0:07:38Not exactly the line I was hoping for!
0:07:38 > 0:07:39Agh!
0:07:39 > 0:07:42A slight lack of control, but really good fun.
0:07:44 > 0:07:48Rapids show us that a gentle river can suddenly gain dangerous power -
0:07:48 > 0:07:51a good reason never to explore rivers unaccompanied.
0:07:53 > 0:07:55But water doesn't have to flow quickly to erode.
0:07:55 > 0:07:59Even the tiniest particles carried along in the water
0:07:59 > 0:08:02help scour away the rock.
0:08:02 > 0:08:06This is how the river could have looked thousands of years ago.
0:08:07 > 0:08:09And this is how it looks now.
0:08:10 > 0:08:12Even now, when the water seems quite calm,
0:08:12 > 0:08:14it's working its way slowly, slowly,
0:08:14 > 0:08:18eating away at the rock, carving its way deeper.
0:08:18 > 0:08:21In millions of years, who knows how deep it will be?
0:08:23 > 0:08:24I hear rapids!
0:08:25 > 0:08:26Sounds terrifying!
0:08:29 > 0:08:32Rivers that descend steeply tend to erode downwards
0:08:32 > 0:08:35and cut high, V-shaped banks.
0:08:35 > 0:08:38Landslides are more likely to occur here than on gentler,
0:08:38 > 0:08:41wider rivers with more sideways erosion.
0:08:51 > 0:08:54The eroded rocks, close up, are almost alien.
0:08:54 > 0:08:56They're smooth and fluid,
0:08:56 > 0:08:59and look like a frozen version of the water that has shaped them.
0:09:00 > 0:09:04You see these deep channels that have been cut down into the rock?
0:09:04 > 0:09:06Well, these pebbles scoured them out
0:09:06 > 0:09:09over thousands and thousands of years.
0:09:09 > 0:09:11You know when you pull a plug out of your bath tub?
0:09:11 > 0:09:13It makes those little whirlpools.
0:09:13 > 0:09:16That's kind of what happens in the river - they're called eddies.
0:09:16 > 0:09:18These pebbles go round and round
0:09:18 > 0:09:20and scour out these beautiful channels.
0:09:23 > 0:09:26It's been a real privilege to travel this gorge,
0:09:26 > 0:09:27going with the flow
0:09:27 > 0:09:30like one of the billions of tiny floating particles,
0:09:30 > 0:09:32dwarfed by the very cliffs they help create.
0:09:41 > 0:09:432012 was wet.
0:09:43 > 0:09:45It rained and it rained
0:09:45 > 0:09:47and it rained.
0:09:47 > 0:09:50By December, it had been officially declared
0:09:50 > 0:09:52the second wettest year since records began.
0:09:53 > 0:09:56And then, at Christmas, this happened.
0:09:59 > 0:10:02A massive landslide tore a huge chunk of land
0:10:02 > 0:10:05off the north coast of the Isle of Wight.
0:10:05 > 0:10:06It destroyed the concrete sea wall
0:10:06 > 0:10:10that was protecting the slope from wave erosion.
0:10:10 > 0:10:13So if the sea didn't cause this landslide, what did?
0:10:14 > 0:10:18Everyone who grows up on the Isle of Wight knows the warning signs
0:10:18 > 0:10:20to look for. Danny and Kieran live nearby.
0:10:20 > 0:10:24You start to see sort of cracks
0:10:24 > 0:10:27and, occasionally, some rocks tumbling down,
0:10:27 > 0:10:29so it gradually slips away.
0:10:29 > 0:10:32Eventually, it just goes.
0:10:32 > 0:10:34Also, when just little chunks
0:10:34 > 0:10:35of rock fall down
0:10:35 > 0:10:37and they're soft, so as they're falling down,
0:10:37 > 0:10:39they break into littler bits.
0:10:39 > 0:10:42That's also a sign that the land could go any minute.
0:10:42 > 0:10:45If you feel how soft the rock is.
0:10:45 > 0:10:46That's really quite soft.
0:10:46 > 0:10:49That would give way quite easily.
0:10:49 > 0:10:51That's basically what we're walking along.
0:10:51 > 0:10:54At the top, it's the mud that's just dried up
0:10:54 > 0:10:56that makes it hard and seem like it's all right.
0:10:56 > 0:10:58But, underneath, it's really soft.
0:10:58 > 0:11:00We have special permission to visit
0:11:00 > 0:11:04the foot of the recent giant landslide, now thought to be stable.
0:11:04 > 0:11:07The same can't be said for the path.
0:11:08 > 0:11:11I can't believe... This path, you used to be able to walk along it,
0:11:11 > 0:11:15but the full force pushed this pathway right out into the sea.
0:11:15 > 0:11:17It used to be a straight path.
0:11:17 > 0:11:18It used to have no cracks.
0:11:18 > 0:11:21It used to be good for walking, cycling, running.
0:11:21 > 0:11:24- It was never an empty path. - It is really scary.
0:11:24 > 0:11:27If you look, at the earth that was there, now,
0:11:27 > 0:11:29it used to be up on that thing.
0:11:29 > 0:11:33We didn't actually put the cracks and all the things together
0:11:33 > 0:11:37to come up with the idea of a landslide, so we were like, "What?!"
0:11:37 > 0:11:39This all sounds quite scary to me,
0:11:39 > 0:11:43but Danny and Kieran have grown up with landslides.
0:11:43 > 0:11:46If you're a bit worried about it, don't worry,
0:11:46 > 0:11:48cos it will come down, usually, quite slowly,
0:11:48 > 0:11:50so you should be able to get away.
0:11:50 > 0:11:52Also, the best safety precautions are put in place,
0:11:52 > 0:11:54so if there is any risk of a landslide,
0:11:54 > 0:11:56the path will be sealed off,
0:11:56 > 0:11:58so there's no risk that anybody can get hurt.
0:11:58 > 0:12:00After safety checks,
0:12:00 > 0:12:03I'm allowed to walk out further onto the landslide itself.
0:12:03 > 0:12:07It really brings home the forces locked within the land.
0:12:07 > 0:12:10Forces that a sea wall is powerless to control.
0:12:11 > 0:12:13Standing here on the landslide,
0:12:13 > 0:12:15you can really feel the power of the rocks
0:12:15 > 0:12:18that must have forced their way down,
0:12:18 > 0:12:20pushing the concrete path there out,
0:12:20 > 0:12:24like it was a piece of paper. So what happened?
0:12:25 > 0:12:27The landslide started behind the sea wall,
0:12:27 > 0:12:31so it couldn't have been caused by sea erosion from the waves.
0:12:31 > 0:12:34But 2012 was the second wettest year on record.
0:12:34 > 0:12:36Here's the monthly rainfall.
0:12:36 > 0:12:38And, according to the
0:12:38 > 0:12:39British Geological Survey,
0:12:39 > 0:12:41there were way more landslides
0:12:41 > 0:12:42than usual,
0:12:42 > 0:12:44shown here in green. In December,
0:12:44 > 0:12:47around five times as many.
0:12:47 > 0:12:49If you compare the monthly rainfall
0:12:49 > 0:12:51with the number of landslides,
0:12:51 > 0:12:52they follow the same pattern,
0:12:52 > 0:12:55so the record rain is causing the record landslides.
0:13:01 > 0:13:04With the help of Kieran, Danny and his mates,
0:13:04 > 0:13:07I am going to show you how rain can cause landslides
0:13:07 > 0:13:11even miles away from the sea. But first, we have to build a hill.
0:13:11 > 0:13:13On your way, guys!
0:13:13 > 0:13:18'The ground we stand on is made up of different sorts of material.'
0:13:18 > 0:13:22We're building our hill on a rock which is impermeable,
0:13:22 > 0:13:24which means it doesn't soak up water.
0:13:24 > 0:13:28But some rock is permeable, which means it does soak up water,
0:13:28 > 0:13:31just like this sand.
0:13:31 > 0:13:33These different types of rock can make a big difference
0:13:33 > 0:13:35when it comes to landslides.
0:13:35 > 0:13:37So, thanks to these guys, I've got my hill
0:13:37 > 0:13:40and I've learned my lesson from last time,
0:13:40 > 0:13:43so I built the castle on top of it.
0:13:43 > 0:13:44But, oh, no, this is the UK
0:13:44 > 0:13:48and the one thing we can rely on is the rain.
0:13:50 > 0:13:52- Oh! - SHE LAUGHS
0:13:53 > 0:13:58As the rain falls on the hills, some water runs off as rivers.
0:13:58 > 0:14:01But if the ground is permeable, it soaks up the rain
0:14:01 > 0:14:04and starts to get heavier, like our sand here.
0:14:04 > 0:14:08Add in other danger factors, like a steep slope,
0:14:08 > 0:14:10weaker or impermeable rock below,
0:14:10 > 0:14:13and you have the perfect recipe for instability.
0:14:13 > 0:14:16Our wet, heavy, rock begins to slide.
0:14:18 > 0:14:20ALL: Yes!
0:14:21 > 0:14:23- Yes!- Nearly, nearly!
0:14:25 > 0:14:28The Isle of Wight has it tough, with both the sea
0:14:28 > 0:14:30and weather causing landslides.
0:14:30 > 0:14:34But stick around because the islanders are fighting back.
0:14:36 > 0:14:39Later in the show, I'll be taking the battle against landslides
0:14:39 > 0:14:42to new heights. Plus, the amusement park
0:14:42 > 0:14:46where the ground itself is a white-knuckle ride.
0:14:46 > 0:14:50But first, Dougal is in Yorkshire to find out how underground water
0:14:50 > 0:14:52creates the most feared land
0:14:52 > 0:14:54movement of them all.
0:14:55 > 0:14:57This is a sinkhole.
0:14:57 > 0:14:59Houses, cars,
0:14:59 > 0:15:01even whole street blocks, have been damaged
0:15:01 > 0:15:04when the ground suddenly gives way.
0:15:04 > 0:15:07And if you want to know what causes these awesome phenomena, you can
0:15:07 > 0:15:11find them right here in the UK, where they're not quite as scary -
0:15:11 > 0:15:14unless you're hanging over the edge of one.
0:15:14 > 0:15:17This is Alum Pot, a gigantic sinkhole
0:15:17 > 0:15:20in the Yorkshire Dales that's 80m deep.
0:15:20 > 0:15:23You could fit Nelson's Column in there.
0:15:23 > 0:15:27It's beautiful from here, but a little scary from the edge.
0:15:27 > 0:15:30But like everything on our fierce Earth,
0:15:30 > 0:15:34sinkholes are a lot less scary when you understand them.
0:15:34 > 0:15:35Woo!
0:15:37 > 0:15:41This area in the Yorkshire Dales is what's known as a karst landscape,
0:15:41 > 0:15:44a type of land recognisable by its pitted surface
0:15:44 > 0:15:46and numerous sinkholes.
0:15:46 > 0:15:49Karst formations can be found across the UK
0:15:49 > 0:15:53and they're all made of the same type of rock - limestone.
0:15:54 > 0:15:58Here is a stunning example of a limestone pavement.
0:15:58 > 0:16:01The rocks beneath my feet are riddled with holes,
0:16:01 > 0:16:04a bit like a wood-infested floorboard,
0:16:04 > 0:16:07and it's this landscape that holds the key to sinkholes.
0:16:09 > 0:16:13This amazing eroded rock only hints at the fierce forces
0:16:13 > 0:16:15at work in these peaceful valleys.
0:16:15 > 0:16:18The real action is deep underground.
0:16:20 > 0:16:24This is how sinkholes happen.
0:16:24 > 0:16:28Here is a mini-version of the landscape that's all around us.
0:16:28 > 0:16:29The sugar cubes beneath
0:16:29 > 0:16:32are the limestone that you can see that I am sitting on,
0:16:32 > 0:16:35and the sand above is the soil on top.
0:16:36 > 0:16:42Just like the limestone, the sugar cubes are strong,
0:16:42 > 0:16:44but they can also be dissolved in water.
0:16:44 > 0:16:47Mmm. Tasty.
0:16:47 > 0:16:49So what happens when it rains?
0:16:50 > 0:16:54As the water pours down on to the soil, it filters down through,
0:16:54 > 0:16:58until it hits the limestone - the sugar cubes in this example.
0:16:58 > 0:17:00There, it can start to dissolve the limestone.
0:17:00 > 0:17:04Rainwater is naturally acidic and this aids that process.
0:17:04 > 0:17:06The limestone dissolves, the sugar cubes dissolve,
0:17:06 > 0:17:07they leave hollows
0:17:07 > 0:17:12and the ground literally falls from underneath your feet.
0:17:12 > 0:17:13That's how you make a sinkhole.
0:17:15 > 0:17:19This erosion is exactly what created Alum Pot.
0:17:19 > 0:17:22The underground water here has built a cave system that will lead me
0:17:22 > 0:17:25right into the centre of the giant sinkhole itself.
0:17:27 > 0:17:30You should never, ever enter caves unaccompanied,
0:17:30 > 0:17:34so I've got expert caver, Jane, as my guide.
0:17:34 > 0:17:37One of the underground streams breaks the surface
0:17:37 > 0:17:39a couple of hundred metres from the pot.
0:17:39 > 0:17:43This is our entrance into the secret world of sinkholes.
0:17:46 > 0:17:48As the stream enters the cave system,
0:17:48 > 0:17:51you can see how it's opening out the cracks,
0:17:51 > 0:17:56dissolving, carving, sculpting the rock
0:17:56 > 0:17:59as it plunges further and further into the Earth,
0:17:59 > 0:18:01and that's where we're going to follow it.
0:18:06 > 0:18:08There you go. Down you go. Don't fall in,
0:18:08 > 0:18:10but, if you do, don't worry.
0:18:10 > 0:18:12There is a very cold pool at the bottom to catch you.
0:18:12 > 0:18:15- There's a cold pool to stop me.- Very cold.- Oh!
0:18:15 > 0:18:17- Hold on tight!- OK.
0:18:24 > 0:18:27The path of the stream soon splits and becomes harder to follow.
0:18:27 > 0:18:32The cave system is like a maze built by water, as it squeezes
0:18:32 > 0:18:35and eats its way relentlessly through the limestone.
0:18:36 > 0:18:38It's getting really tight now.
0:18:38 > 0:18:42'Things are about to get a lot tighter.'
0:18:42 > 0:18:45They call this gap the Cheese Press.
0:18:45 > 0:18:48Apparently, I've got to squeeze through this
0:18:48 > 0:18:49to get to the other side.
0:18:49 > 0:18:51I don't even think my helmet can make it through.
0:18:51 > 0:18:54You might have to take your helmet off, but you can get through.
0:18:54 > 0:18:55Wish me luck.
0:19:00 > 0:19:02HE LAUGHS This is incredible!
0:19:05 > 0:19:07Phew!
0:19:11 > 0:19:15Now I know why they call it the Cheese Press! Oh!
0:19:15 > 0:19:18I really hope there's another way out of here.
0:19:25 > 0:19:26Just look at this!
0:19:27 > 0:19:30You can actually see the cracks and joints in the rock
0:19:30 > 0:19:33where the water's percolating through and dissolving it.
0:19:33 > 0:19:35And, here...
0:19:35 > 0:19:40Here's a big chunk of rock that's fallen from just up there. Bang!
0:19:40 > 0:19:43There's thousands of tonnes of rock above our head
0:19:43 > 0:19:46and the river is still going deeper and deeper into the Earth.
0:19:46 > 0:19:51This process has been happening for thousands and thousands of years
0:19:51 > 0:19:52and it's still happening today.
0:19:52 > 0:19:54Wow!
0:19:54 > 0:19:58Not many people get to crawl through the secret plumbing of the Earth.
0:19:59 > 0:20:04The water that is endlessly at work is leading us closer to our goal -
0:20:04 > 0:20:09a view of the giant Alum Pot sinkhole that few ever see.
0:20:09 > 0:20:11One last obstacle remains.
0:20:11 > 0:20:14It has to be the thinnest ladder I've ever been on.
0:20:14 > 0:20:16Light at the end of the tunnel!
0:20:17 > 0:20:20And what a light it is.
0:20:20 > 0:20:24The stream has brought me back to where my journey began,
0:20:24 > 0:20:28to the incredible sinkhole the water itself created - Alum Pot.
0:20:29 > 0:20:31Ominous from above,
0:20:31 > 0:20:34a wondrous secret world from below.
0:20:38 > 0:20:42That's amazing! Wow!
0:20:45 > 0:20:49I started my journey just up there, skipped down waterfalls,
0:20:49 > 0:20:51literally been squeezed through the Earth
0:20:51 > 0:20:54and I've come here to see Alum Pot in its full glory.
0:20:54 > 0:20:57I just want to go one stage further.
0:21:01 > 0:21:05My final goal is suspended in the very middle of the abyss...
0:21:06 > 0:21:08..a precarious, fallen boulder.
0:21:12 > 0:21:15My journey to this spot has been tough
0:21:15 > 0:21:19and not something you should ever attempt without an expert guide.
0:21:19 > 0:21:22But standing in the centre of this incredible sinkhole,
0:21:22 > 0:21:24it's been more than worth it.
0:21:34 > 0:21:36The powerful forces that cause landslides
0:21:36 > 0:21:39are never going to go away.
0:21:39 > 0:21:42So how do humans deal with the risk?
0:21:42 > 0:21:43Here on the Isle of Wight,
0:21:43 > 0:21:46islanders know better than most people
0:21:46 > 0:21:48that what goes up
0:21:48 > 0:21:51must come down!
0:21:51 > 0:21:53Whoo-hoo!
0:22:00 > 0:22:05Blackgang Chine is the oldest amusement park in the world.
0:22:05 > 0:22:07It first opened in 1843
0:22:07 > 0:22:10and generations of families have come here
0:22:10 > 0:22:13since the island became fashionable in Victorian times.
0:22:13 > 0:22:16The park has changed a lot since then,
0:22:16 > 0:22:19but so has the very land it sits on.
0:22:19 > 0:22:22The chine that gives Blackgang its name
0:22:22 > 0:22:24came close to destroying it.
0:22:27 > 0:22:32A chine is a narrow gorge on the coast, formed by water erosion.
0:22:32 > 0:22:34The small chine at Blackgang
0:22:34 > 0:22:37has grown into a vast gash in the coastline,
0:22:37 > 0:22:41with landslides sitting on top of landslides.
0:22:41 > 0:22:43Erosion rates average four metres a year,
0:22:43 > 0:22:48but heavy rains have seen losses of up to 40 metres in one year.
0:22:48 > 0:22:51The park is being eaten away.
0:22:51 > 0:22:54The last major landslide here was in 1994,
0:22:54 > 0:22:58when a third of the existing park moved.
0:22:58 > 0:23:01If you look really carefully, you can see the remains
0:23:01 > 0:23:05of the old Wild West-themed area that had to be abandoned.
0:23:15 > 0:23:20Was Blackgang Chine about to go the way of dinosaurs?
0:23:20 > 0:23:25You don't keep going for 170 years without learning a few tricks.
0:23:25 > 0:23:27The chine is constantly monitored for movement,
0:23:27 > 0:23:31so nobody was hurt when the Wild West finally slipped away.
0:23:31 > 0:23:35The owners of the park did what they had always done - regrouped,
0:23:35 > 0:23:38re-planned and rebuilt.
0:23:38 > 0:23:42This is the new Wild West area, built on higher, more stable ground.
0:23:42 > 0:23:45In summer, 5,000 people a day come here,
0:23:45 > 0:23:47most of them oblivious to the challenges
0:23:47 > 0:23:50that winter rains bring to Blackgang Chine.
0:23:50 > 0:23:54An amusement park that has adapted to the times and landslides.
0:23:57 > 0:24:00Just along the coast from Blackgang Chine,
0:24:00 > 0:24:05a very 21st-century battle against landslides is taking place,
0:24:05 > 0:24:07and the islanders are winning.
0:24:08 > 0:24:10Work is going on all across the Isle of Wight
0:24:10 > 0:24:12to make sure the coast is safe.
0:24:12 > 0:24:14It's happening above me right now -
0:24:14 > 0:24:18it's called landslide mitigation - and it's a massive job.
0:24:18 > 0:24:21After all, they're holding a cliff together.
0:24:23 > 0:24:26The clifftop path here is popular with local walkers,
0:24:26 > 0:24:30but a recent landslip means it's too dangerous to use.
0:24:30 > 0:24:34And the Hideaway Cafe is in danger of slipping away.
0:24:34 > 0:24:37In the past, the path might have been left to disappear,
0:24:37 > 0:24:41but modern techniques mean there's hope for the cafe yet.
0:24:41 > 0:24:45The council has called in an expert landslide mitigation team
0:24:45 > 0:24:49to make the cliff safe over a sheer drop 40 metres above the beach
0:24:49 > 0:24:51and I'm the newest recruit.
0:24:51 > 0:24:56- You feel nice and snug?- Yes.- OK, brilliant. Come round here. OK?
0:24:56 > 0:24:59- 'Simon shows me the ropes...' - Right, you can pull across this way.
0:24:59 > 0:25:00'..and pulleys...'
0:25:00 > 0:25:02- That's you descending. - '..and levers.'
0:25:02 > 0:25:04If you want to stop, you can let go of everything
0:25:04 > 0:25:07- and that pulls tight.- Good.
0:25:07 > 0:25:11- That's nice and secure. You do have to trust this kit.- You do.
0:25:11 > 0:25:15If I step down here, and then you can follow me down.
0:25:15 > 0:25:18- Lovely!- Whoo, incoming! - Yeah, no problem.
0:25:18 > 0:25:22'The wooden wall is the first step in making the coastal path safe.
0:25:22 > 0:25:25'It will reinforce the path foundations by stopping them
0:25:25 > 0:25:29'from sliding in wet weather, so it has to be very secure.'
0:25:29 > 0:25:31And we are pretty much ready to go.
0:25:31 > 0:25:32Whoo!
0:25:34 > 0:25:36- We are just going to let the drill do the work.- Yep.
0:25:39 > 0:25:41OK, pull backwards.
0:25:42 > 0:25:44'Longer and longer drill bits are added
0:25:44 > 0:25:46'as we drill deeper and deeper.'
0:25:46 > 0:25:49We are going to go back in again.
0:25:49 > 0:25:53'It's a tough job drilling two metres into the sticky, wet clay.'
0:25:53 > 0:25:55Woo!
0:25:56 > 0:25:59- OK.- 'Two-metre hole drilled.'
0:25:59 > 0:26:02'Time to insert a two-metre reinforced steel bolt
0:26:02 > 0:26:05'to hold up the wood that's holding up the earth
0:26:05 > 0:26:07'that's holding up the path!'
0:26:07 > 0:26:11- That's right.- OK.- He's going to sit over the end.- There we go.
0:26:11 > 0:26:13- Fantastic.- How long do you think this will last,
0:26:13 > 0:26:17- a structure like this?- More than our lifetime, hopefully.- Wow!
0:26:17 > 0:26:19'The path is on its way to being rebuilt.
0:26:19 > 0:26:23'Next job is to secure the loose earth below with plastic mat
0:26:23 > 0:26:25'and wire netting.
0:26:25 > 0:26:28'The holes allow plants to regrow through into the slope
0:26:28 > 0:26:31'and bind the earth together with their roots.
0:26:31 > 0:26:35'Stability with a little help from mother nature.'
0:26:35 > 0:26:36You can't even see the rock netting now
0:26:36 > 0:26:39and that's what we want. We want lots of vegetation
0:26:39 > 0:26:42to help stick everything on the top together.
0:26:44 > 0:26:45Nice and tight on there.
0:26:48 > 0:26:51- This is the final one.- Lovely. I'll just put my foot on there.- Yep.
0:26:51 > 0:26:54And we'll feed him round and underneath.
0:26:54 > 0:26:57'Since the early 1990s, the council here has spent
0:26:57 > 0:27:00'over £5 million on cliff stabilisation.'
0:27:00 > 0:27:03Landslides will always be with us here in the UK.
0:27:03 > 0:27:05The waves will always pound at the coast
0:27:05 > 0:27:09and, let's face it, the rain will always fall.
0:27:09 > 0:27:10But the human ingenuity
0:27:10 > 0:27:14in the face of the Fierce Earth will always remain.
0:27:15 > 0:27:18Although landslides that injure people are rare,
0:27:18 > 0:27:21they are one threat that will never go away.
0:27:21 > 0:27:24But we can learn to live alongside them,
0:27:24 > 0:27:29analysing the ground, controlling the risks
0:27:29 > 0:27:32and rebuilding when needed.
0:27:32 > 0:27:37This is how we maximise our chances of surviving the Fierce Earth.
0:27:39 > 0:27:42Next time, things are hotting up underground.
0:27:44 > 0:27:47And I dive to the spot where the Earth tears itself apart.
0:27:47 > 0:27:48Wish me luck.