0:00:02 > 0:00:04Skiing, snowboarding, sledging!
0:00:04 > 0:00:07Here in the Alps, it's full of people having the time of their lives
0:00:07 > 0:00:11in some of the most spectacular scenery on the planet.
0:00:12 > 0:00:17But snow, the white fluffy stuff that everyone comes here for,
0:00:17 > 0:00:19the very thing that makes it fun,
0:00:19 > 0:00:22can also put you in mortal danger.
0:00:22 > 0:00:26Here in the mountains, it's the word everybody fears...
0:00:26 > 0:00:27- Avalanche!- Avalanche!
0:00:29 > 0:00:34Get suited and booted, cos we're travelling to avalanche country,
0:00:34 > 0:00:37skiing in the shadow of the biggest threat in the mountains...
0:00:37 > 0:00:40This is the run where the avalanche happened.
0:00:40 > 0:00:43..checking out cutting-edge survival tech,
0:00:43 > 0:00:45taking on nature in a man versus snow race...
0:00:47 > 0:00:51..and prevention - fighting avalanche with avalanche.
0:00:57 > 0:01:01What happens when the ground shakes, the seas rise up
0:01:01 > 0:01:04and the air tears itself apart?
0:01:04 > 0:01:06The Fierce Earth team move in,
0:01:06 > 0:01:09taking on the most powerful forces on the planet.
0:01:25 > 0:01:27Get ready for Fierce Earth -
0:01:27 > 0:01:29the Earth, and how to survive it.
0:01:33 > 0:01:35This is an avalanche.
0:01:35 > 0:01:40Hundreds of tonnes of snow travelling in excess of 150 miles per hour.
0:01:41 > 0:01:44Spectacular, beautiful, deadly.
0:01:44 > 0:01:49If it hits you, you're along for the ride all the way to the bottom.
0:01:49 > 0:01:52And the cause of this terrifying moving cliff of snow?
0:01:52 > 0:01:55Well, sometimes it's this.
0:01:55 > 0:01:56Me.
0:01:58 > 0:02:00Well, not just you, Dougal.
0:02:01 > 0:02:04In 90% of all avalanche incidents where people get hurt,
0:02:04 > 0:02:07it's the very people caught up in the avalanche
0:02:07 > 0:02:09or their ski party that trigger it.
0:02:10 > 0:02:11Check out Dougal's skis.
0:02:11 > 0:02:13Every time he makes a turn,
0:02:13 > 0:02:16he moves the snow and that creates lots of mini avalanches.
0:02:16 > 0:02:18Take a close look at that,
0:02:18 > 0:02:21because it holds the secret to avalanche survival.
0:02:21 > 0:02:23You said you wanted a closer look!
0:02:23 > 0:02:27To understand avalanches, you've got to understand snow.
0:02:28 > 0:02:30We've come to Tignes,
0:02:30 > 0:02:33a major ski resort over 2,000 metres high in the French Alps.
0:02:35 > 0:02:38Tignes has over 300km of marked ski runs called pistes,
0:02:38 > 0:02:42and many more miles of unmarked off-piste skiing.
0:02:42 > 0:02:44In short, there's a lot of snow.
0:02:47 > 0:02:50Snow is always cold and always white,
0:02:50 > 0:02:53but, other that that, it has endless variety,
0:02:53 > 0:02:56which can all add up to increased avalanche risk.
0:02:58 > 0:03:00How snow falls...
0:03:00 > 0:03:02Does it float gently down like a Christmas card?
0:03:02 > 0:03:05Or get blasted out of the sky like a blizzard?
0:03:06 > 0:03:07How it collects...
0:03:07 > 0:03:09As snow lands on the ground,
0:03:09 > 0:03:13it can build up in soft drifts or pack into icy sheets.
0:03:13 > 0:03:14The weather...
0:03:14 > 0:03:18Snow can melt or refreeze days or even weeks after it fell.
0:03:18 > 0:03:20It's constantly changing.
0:03:21 > 0:03:25We all know that every single snowflake is unique, right?
0:03:25 > 0:03:26As individual as you and I.
0:03:28 > 0:03:30But that hasn't been conclusively proven, Dougal.
0:03:32 > 0:03:35The classic snowflake, the six-pointed crystal,
0:03:35 > 0:03:39interlocks more easily with other six-sided snow crystals
0:03:39 > 0:03:40to form a stable layer.
0:03:40 > 0:03:44But some snow crystals have less points, almost like grains of sugar.
0:03:44 > 0:03:48They can't interlock and are therefore unstable.
0:03:48 > 0:03:50And then, with all the freezing and unfreezing,
0:03:50 > 0:03:52there's lots of shapes in between.
0:03:52 > 0:03:56Some are unstable, and some are very stable indeed.
0:03:58 > 0:04:00How snow falls, how it collects, the weather,
0:04:00 > 0:04:02the snow crystals themselves...
0:04:02 > 0:04:05It's clear that predicting an avalanche is far from easy,
0:04:05 > 0:04:09and prediction is pretty urgent here in Europe's Alps,
0:04:09 > 0:04:12with around 250,000 avalanches every year.
0:04:14 > 0:04:18In 1999, high levels of snow and changing weather created
0:04:18 > 0:04:20an unstable layer of snow high above
0:04:20 > 0:04:23the village of Galtur, in Austria.
0:04:23 > 0:04:24Over 150,000 tonnes of snow
0:04:24 > 0:04:26travelled down the mountain
0:04:26 > 0:04:28in less than a minute.
0:04:28 > 0:04:3031 people lost their lives.
0:04:31 > 0:04:34Scientists can't predict avalanches,
0:04:34 > 0:04:37but by studying the snow pack that has collected on the mountain,
0:04:37 > 0:04:41they can tell when and where avalanches are more likely.
0:04:41 > 0:04:44As can be shown by making a classic French gateaux.
0:04:46 > 0:04:51Avalanches are formed when the weight of snow above, the load,
0:04:51 > 0:04:54is too heavy for the snow beneath
0:04:54 > 0:04:57and the whole snow pack fails.
0:04:57 > 0:05:04Avalanches usually form on slopes that are between 25 and 45 degrees.
0:05:04 > 0:05:07Too flat, and the snow that's settling
0:05:07 > 0:05:10is pushed into the ground by gravity.
0:05:10 > 0:05:14Too steep, and the snow doesn't actually settle at all
0:05:14 > 0:05:16to form to dangerous levels.
0:05:18 > 0:05:23But then, you have to add the ever changing snow types into the mix.
0:05:23 > 0:05:25So, we have an unstable layer...
0:05:25 > 0:05:29- Cream here.- And then a more solid stable layer on top of that.
0:05:29 > 0:05:32And maybe then some more slippery, slushy stuff on top of that.
0:05:32 > 0:05:34So some more creamy snow.
0:05:34 > 0:05:36And then, perhaps some graupel -
0:05:36 > 0:05:38a type of snow that's like icy ball bearings.
0:05:40 > 0:05:43And it's very unstable. And then, another solid layer.
0:05:43 > 0:05:46And then, we're building the gateaux with more slippery,
0:05:46 > 0:05:50slushy stuff, and then we've got some more stable snow.
0:05:50 > 0:05:52- Oh!- Oh!
0:05:52 > 0:05:55And then, the snow is all melting and reforming,
0:05:55 > 0:05:59melting and reforming, creating some stable and some unstable layers.
0:05:59 > 0:06:04And there you have it, a teetering gateaux, ready to fall.
0:06:04 > 0:06:07And it's now that the conditions are ripe for one of the most
0:06:07 > 0:06:09feared avalanches of all -
0:06:09 > 0:06:11the dreaded slab avalanche.
0:06:13 > 0:06:15The weak layers can't support the strong layers
0:06:15 > 0:06:18and the whole slab slips away.
0:06:24 > 0:06:27The slab avalanche is one of the most dangerous
0:06:27 > 0:06:30and causes the majority of skiing fatalities.
0:06:30 > 0:06:35In 2012, there were 70 avalanche casualties in the European Alps.
0:06:36 > 0:06:39Despite the risks, winter sports enthusiasts
0:06:39 > 0:06:43from all over the world travel to the Alps to have fun on the snow.
0:06:43 > 0:06:45And there are many that call the mountains home.
0:06:47 > 0:06:49This is Charles and Mathieu Navillod in action -
0:06:49 > 0:06:52two local brothers who grew up in Tignes.
0:06:52 > 0:06:53They're expert skiers,
0:06:53 > 0:06:56who have represented France in international competition.
0:06:56 > 0:06:59But they also know about avalanche danger first hand.
0:07:02 > 0:07:04Charles is lucky to be alive.
0:07:04 > 0:07:08I met up with him and his brother to find out his avalanche story.
0:07:09 > 0:07:12So, as brothers, you've been growing up here in the mountains.
0:07:12 > 0:07:13Tell me a little about that.
0:07:13 > 0:07:15Yeah, we start ski at two years old.
0:07:15 > 0:07:18- Wow, so you're literally born with skis, almost.- Yeah.
0:07:18 > 0:07:20What do you like so much about off-piste skiing?
0:07:20 > 0:07:26- It's freedom.- Feel free, like flying on the snow.
0:07:26 > 0:07:29Be alone, far from the city.
0:07:29 > 0:07:32You must, obviously, develop an understanding
0:07:32 > 0:07:34and a feeling about avalanches.
0:07:34 > 0:07:39We learn every day in the mountains and we never have zero risk.
0:07:39 > 0:07:42Like, today, it looks not dangerous
0:07:42 > 0:07:45but we can find some steep parts, we can make avalanche, for sure.
0:07:45 > 0:07:48- So we have to be careful every time. - Always have to be aware.
0:07:48 > 0:07:51I mean, it's really hard to stay at home when it's, like,
0:07:51 > 0:07:55beautiful powder snow, but sometimes we have to say,
0:07:55 > 0:07:59"OK, today, it's too much risks."
0:07:59 > 0:08:02It's clear that Charles and Mathieu are experts skiers,
0:08:02 > 0:08:06but even they have a near-miss avalanche tale to tell.
0:08:06 > 0:08:09They want to share it, so that others might learn from it.
0:08:09 > 0:08:10What happened to them
0:08:10 > 0:08:14could happen to anyone who leaves the smooth, marked piste.
0:08:14 > 0:08:18Guys, we've just, literally, stepped off a very easy piste
0:08:18 > 0:08:22and, clearly, just over here it's very steep and definitely off-piste.
0:08:22 > 0:08:24What is it we're going to go and see?
0:08:24 > 0:08:26Two weeks ago, we had an avalanche just there.
0:08:26 > 0:08:27An avalanche just over here?
0:08:27 > 0:08:30Yeah, just next to the slope, so I'm going to show you.
0:08:30 > 0:08:32- So, you can take us to the place where it is?- Yeah.
0:08:32 > 0:08:35Brilliant! Let's go and have a look.
0:08:35 > 0:08:36You should never go off-piste
0:08:36 > 0:08:38without an experienced guide.
0:08:38 > 0:08:40I'm able to because Charles
0:08:40 > 0:08:43and Mathieu are professional ski instructors.
0:08:43 > 0:08:46Off-piste is where the snow is deep and unpredictable and the risk of
0:08:46 > 0:08:48avalanche is greatest.
0:08:48 > 0:08:50Two weeks before our meeting,
0:08:50 > 0:08:51Charles was skiing through
0:08:51 > 0:08:53the trees here when he was caught up
0:08:53 > 0:08:55in every skier's worst nightmare.
0:08:57 > 0:08:59This is the run where the avalanche happened.
0:08:59 > 0:09:02So I started by the trees there.
0:09:02 > 0:09:04The whole avalanche was recorded
0:09:04 > 0:09:06on Charles' mini helmet camera.
0:09:06 > 0:09:08Here you can see how the snow
0:09:08 > 0:09:09sweeps him off his feet
0:09:09 > 0:09:11and over the edge of the cliff.
0:09:13 > 0:09:14I did the first turn
0:09:14 > 0:09:17and avalanche started directly.
0:09:17 > 0:09:19So, I have to drop that cliff down here,
0:09:19 > 0:09:21but the avalanche goes so fast.
0:09:21 > 0:09:26You feel really the power of the snow for four, five seconds.
0:09:26 > 0:09:30It was really short, but it feels so long and it was scary
0:09:30 > 0:09:33and I could only think about protecting my face.
0:09:33 > 0:09:35So what actually stopped you going all the way down the
0:09:35 > 0:09:37- hill with the avalanche? - So, that small tree.
0:09:37 > 0:09:40Wow, it doesn't look like much
0:09:40 > 0:09:42but that's the actual tree that saved your life.
0:09:45 > 0:09:47And how much further did the avalanche carry on?
0:09:47 > 0:09:49It stopped, like, 20,
0:09:49 > 0:09:5030 metres down the snow.
0:09:50 > 0:09:55It was a really short avalanche, like, 80 metres from the top.
0:09:55 > 0:09:58Did you badly injure yourself, at all?
0:09:58 > 0:10:01Well, I hurt my face, a lot of blood on my face.
0:10:01 > 0:10:04Hurt my leg, but it was two weeks ago and I'm here,
0:10:04 > 0:10:07so I guess I was really, really lucky.
0:10:07 > 0:10:09How do you feel now about skiing this area?
0:10:09 > 0:10:12I feel good, I respect the mountain.
0:10:12 > 0:10:16You know, sometimes it's like that, mountain is stronger than you.
0:10:16 > 0:10:18Charles is one of the lucky ones.
0:10:18 > 0:10:21He was caught up in an avalanche and lived to tell the tale.
0:10:27 > 0:10:30But there are ways to increase your chances of survival,
0:10:30 > 0:10:31if the worst does happen.
0:10:31 > 0:10:34This is footage of a professional snowboarder
0:10:34 > 0:10:36caught in a real-life avalanche.
0:10:36 > 0:10:39He's saved by the latest kit that has been deployed,
0:10:39 > 0:10:41nearly 400 times and claims
0:10:41 > 0:10:43up to 95% survival rate.
0:10:43 > 0:10:45So, what's the secret?
0:10:45 > 0:10:47This.
0:10:52 > 0:10:53HE LAUGHS
0:10:53 > 0:10:54Wow!
0:10:54 > 0:10:56Like all of the best ideas,
0:10:56 > 0:10:59the avalanche air bag is incredibly simple.
0:10:59 > 0:11:02It works on the principle of granular convection.
0:11:04 > 0:11:08Granular convection simply means that large objects tend to move
0:11:08 > 0:11:10to the surface when they're shaken
0:11:10 > 0:11:12around with lots of small objects.
0:11:12 > 0:11:14Time for another French treat!
0:11:14 > 0:11:16The bonbon.
0:11:16 > 0:11:21And there's only one thing better than a bonbon - lots of bonbons.
0:11:25 > 0:11:27The only problem now is, I can't get
0:11:27 > 0:11:32at my big, red bonbon because of all of these little, white bonbons.
0:11:32 > 0:11:35However, if I use granular convection and shake the bottle...
0:11:43 > 0:11:46Voila! I can get at my red bonbon.
0:11:46 > 0:11:49And that's exactly what the avalanche airbag does.
0:11:49 > 0:11:50When I inflate it in an avalanche,
0:11:50 > 0:11:53I suddenly become a giant human-size
0:11:53 > 0:11:58bonbon and I float up amongst all of the snow particles to the very top.
0:11:58 > 0:12:02C'est magnifique! Woo-hoo-hoo!
0:12:07 > 0:12:11Later in the show, I'll be going off-piste with a ski rescue patrol
0:12:11 > 0:12:13and witnessing an avalanche for real.
0:12:15 > 0:12:18But first, Clare's hitching a ride on the machine that helps
0:12:18 > 0:12:20skiers stay on the beaten track.
0:12:22 > 0:12:24It's just gone six o'clock here, in Tignes,
0:12:24 > 0:12:28and the last of the skiers have gone back to the ski resort for the night.
0:12:28 > 0:12:32It's peaceful again up here on the mountain...but not for long.
0:12:35 > 0:12:39That is a state-of-the-art piste basher, it weighs nine tons
0:12:39 > 0:12:43and does a maximum speed of 22 kilometres an hour but the best
0:12:43 > 0:12:47thing about it, it goes up and down really steep mountain sides.
0:12:50 > 0:12:51And I'm going to hitch a ride.
0:12:53 > 0:12:55Ha-ha!
0:12:55 > 0:12:57The piste basher is human beings' attempt to turn
0:12:57 > 0:13:01unpredictable snow into smooth, skiable piste.
0:13:01 > 0:13:03SHE SHRIEKS
0:13:03 > 0:13:04Bladed caterpillar tracks
0:13:04 > 0:13:07allow bashers to travel pretty much anywhere on a mountain.
0:13:07 > 0:13:11So they're sometimes used in avalanche incidents to ferry
0:13:11 > 0:13:13rescue teams and the injured.
0:13:13 > 0:13:16Hundreds of skiers and snowboarders leave bumps
0:13:16 > 0:13:18and ice all over the piste.
0:13:18 > 0:13:21Basher drivers like Didier have to work through the night.
0:13:21 > 0:13:23I you're going to be travelling on the mountain side,
0:13:23 > 0:13:26- this is the best machine to do it.- Yes, definitely.
0:13:26 > 0:13:29The snow just falls either side, it's a perfect
0:13:29 > 0:13:30machine for a mountain side.
0:13:33 > 0:13:37So there's no steering wheel, so how do you control this machine?
0:13:37 > 0:13:41I control it like a tank. One for the left, one for the right.
0:13:41 > 0:13:45This machine's got so much control, as well as power.
0:13:46 > 0:13:49I'm having to brace my feet right now cos we're really going downhill.
0:13:54 > 0:13:57So what is your job after an avalanche?
0:13:57 > 0:14:00We can intervene, erm, after the avalanche
0:14:00 > 0:14:03to rescue some people with the pisteurs.
0:14:09 > 0:14:11We're on top of the world here, it's amazing!
0:14:14 > 0:14:16There's something about being on a mountain side
0:14:16 > 0:14:18when everyone else has gone home.
0:14:18 > 0:14:20So when all the skiers
0:14:20 > 0:14:22and snowboarders are asleep in their beds,
0:14:22 > 0:14:26anticipating the next day's snow, these guys are out all night,
0:14:26 > 0:14:31keeping the slopes safe so they can have a good ski tomorrow.
0:14:31 > 0:14:33They do an amazing job!
0:14:36 > 0:14:39Smooth pistes are just the beginning of keeping skiers safe.
0:14:39 > 0:14:42The real avalanche safety work is going on all over the mountain,
0:14:42 > 0:14:44night and day.
0:14:53 > 0:14:56I've hooked up with the Tignes ski patrol,
0:14:56 > 0:14:58whose job it is to keep the slopes safe.
0:14:58 > 0:15:02The team numbers over 50 crack skiers, called pisteurs,
0:15:02 > 0:15:04plus several rescue dogs.
0:15:04 > 0:15:08First job of the day is to set the avalanche warning level.
0:15:09 > 0:15:13The lifts have only just opened and the slope's already packed.
0:15:13 > 0:15:16We have to tell people the avalanche risk.
0:15:16 > 0:15:18Today it's an avalanche risk of two.
0:15:18 > 0:15:22On a scale of one to five, two's moderate.
0:15:22 > 0:15:25So, Sebastian, there's not really much risk at all?
0:15:25 > 0:15:28Today, the risk is moderate, but still a risk.
0:15:28 > 0:15:32Last week, again, some people was buried and it was a risk two.
0:15:32 > 0:15:34Wow, OK.
0:15:34 > 0:15:36So people can still get caught in avalanches even
0:15:36 > 0:15:37when the risks are relatively low.
0:15:37 > 0:15:42We have coloured flags, so this flag here is a black and yellow flag.
0:15:42 > 0:15:44That's for level three and four, we don't need that.
0:15:44 > 0:15:46I'll give you that back.
0:15:48 > 0:15:51What we need is a level two, yellow flag.
0:15:51 > 0:15:54So, we'll hoist this and this is very important,
0:15:54 > 0:15:58because at all of the stations they have a flag flying with a colour
0:15:58 > 0:16:02that tells people immediately from a distance what the risk is that day.
0:16:02 > 0:16:05So they can be prepared and ready to ski as safely as possible.
0:16:06 > 0:16:08Yeah, we're flying away! Lovely!
0:16:09 > 0:16:13Before venturing off-piste, it's essential that every
0:16:13 > 0:16:18skier in your party has the right kit and knows how to use it.
0:16:18 > 0:16:22These French teenagers are getting transceiver training.
0:16:22 > 0:16:25Each skier's transceiver sends out a signal that the other
0:16:25 > 0:16:27transceivers can pick up,
0:16:27 > 0:16:29if one of the skiers is buried under the snow.
0:16:29 > 0:16:33If an avalanche hits, it's your friends that could save your life.
0:16:37 > 0:16:40So, Sebastian, maybe you can explain a little bit about how these work
0:16:40 > 0:16:42when they're communicating with each other.
0:16:42 > 0:16:45Yeah, exactly, you need two beeps and it's the same frequency
0:16:45 > 0:16:49and if I want to find you, I put the transceiver to the search...
0:16:49 > 0:16:51Search, yeah.
0:16:51 > 0:16:53..erm, like this.
0:16:53 > 0:16:55TRANSCEIVER BEEPS
0:16:55 > 0:16:57I can find you.
0:16:57 > 0:16:59BEEPING GETS LOUDER AND FASTER
0:16:59 > 0:17:02Incredible! So you hear the beeps there,
0:17:02 > 0:17:05when they're further away from you, the beeps are very slow.
0:17:05 > 0:17:08And as the transceiver gets closer to the other transceiver,
0:17:08 > 0:17:11it starts to beep much more rapidly.
0:17:11 > 0:17:13And so, by going along the snow
0:17:13 > 0:17:16and listening to the rate at which the beeps are going, you can
0:17:16 > 0:17:19start to home in and search for your buried victim.
0:17:19 > 0:17:22You told me that you've buried one of these
0:17:22 > 0:17:24transceivers in the snow behind us.
0:17:24 > 0:17:25Yup.
0:17:25 > 0:17:27So our job now is to go and try
0:17:27 > 0:17:29and find what looks like a needle in a haystack.
0:17:34 > 0:17:36In avalanche rescue, every second counts!
0:17:36 > 0:17:40Your chances of survival drop rapidly after 15 minutes
0:17:40 > 0:17:41trapped under the snow.
0:17:43 > 0:17:46The clock has already started ticking down.
0:17:47 > 0:17:50Right, now, you take off your skis.
0:17:50 > 0:17:54So we think it's somewhere close by here, what do I do next?
0:17:54 > 0:17:57You must be across, over there.
0:17:57 > 0:17:59OK, until you get it more and more.
0:17:59 > 0:18:01- Exactly.- So, I'll do that then.
0:18:01 > 0:18:03TRANSCEIVER BEEPS
0:18:03 > 0:18:05It's got lower there...right.
0:18:06 > 0:18:08Getting faster again.
0:18:09 > 0:18:11Zero seven, zero nine.
0:18:12 > 0:18:16Essential avalanche survival kit includes a collapsible probe
0:18:16 > 0:18:18that can be assembled in seconds.
0:18:18 > 0:18:20- OK.- OK, we think it's just down here.
0:18:23 > 0:18:25So using the probe to try and find the location of the victim,
0:18:25 > 0:18:27the person.
0:18:29 > 0:18:31I've found something there.
0:18:31 > 0:18:35And the final stage, we have a collapsible shovel cos it's
0:18:35 > 0:18:39the quickest way possible of digging down to try and find the victim.
0:18:43 > 0:18:47Every second counts...wow, there's something there.
0:18:51 > 0:18:52There's a...
0:18:52 > 0:18:54a rucksack...
0:18:58 > 0:18:59Woo!
0:18:59 > 0:19:02TRANSCEIVER BEEPS QUICKLY
0:19:02 > 0:19:04And there you go, it really works, thank you.
0:19:05 > 0:19:07Excellent stuff.
0:19:14 > 0:19:16Remember, the best thing is not to be caught up
0:19:16 > 0:19:19in an avalanche in the first place.
0:19:19 > 0:19:21Keep your wits about you when venturing off-piste
0:19:21 > 0:19:24and follow our avalanche survival tips.
0:19:25 > 0:19:28One, always check the avalanche risk flags
0:19:28 > 0:19:32and remember that avalanches can happen whatever the warning level.
0:19:32 > 0:19:34Two, never ski alone.
0:19:34 > 0:19:36A guide, a personal rescue kit
0:19:36 > 0:19:39and a transceiver are minimum requirements.
0:19:39 > 0:19:43Three, snow will take the path of least resistance.
0:19:43 > 0:19:46Avalanches are fast but lazy.
0:19:46 > 0:19:49So you might be able to take ski sideways or even move upwards
0:19:49 > 0:19:51out of its way.
0:19:52 > 0:19:55But why can't you just outrun an avalanche?
0:19:55 > 0:19:57Sounds like a challenge for Leo.
0:19:59 > 0:20:02Temperature, a constant -5C.
0:20:05 > 0:20:08A vertical drop of 50m.
0:20:08 > 0:20:12170m of pristine man-made snow.
0:20:12 > 0:20:15This indoor ski slope is about to become my Fierce Earth
0:20:15 > 0:20:17avalanche survival laboratory.
0:20:17 > 0:20:19I spend a lot of time in the mountains
0:20:19 > 0:20:21and avalanches are something that really scare me.
0:20:21 > 0:20:23You have to treat them with the utmost respect.
0:20:23 > 0:20:25There are a very dangerous thing.
0:20:25 > 0:20:27Today, I'm going to see if I can outrun one.
0:20:27 > 0:20:29To be honest, I'm not too sure.
0:20:31 > 0:20:33My challenge is simple.
0:20:33 > 0:20:37Ski as fast as I can down the slope to outrun an avalanche.
0:20:37 > 0:20:40As this is a laboratory experiment, the avalanche will be virtual -
0:20:40 > 0:20:42computer-generated.
0:20:42 > 0:20:45Who will be faster? Me or the snow?
0:20:47 > 0:20:48There's nowhere to hide,
0:20:48 > 0:20:51but I can give myself the best chance of beating
0:20:51 > 0:20:55the avalanche by making sure my skis are in tiptop racing condition.
0:20:55 > 0:20:58So when you ski down a slope, you don't
0:20:58 > 0:21:00slide down on the bases of the skis,
0:21:00 > 0:21:02you cut your way down on the edges.
0:21:02 > 0:21:05They're like knives that cut into the slope.
0:21:05 > 0:21:08Re-wax the base of the skis.
0:21:08 > 0:21:11This wax is to make me go extra fast.
0:21:13 > 0:21:15I adjust the bindings to make sure
0:21:15 > 0:21:18they release my boots in the event of a fall.
0:21:18 > 0:21:22And then, it's time to focus on the challenge ahead.
0:21:32 > 0:21:33I'm all set.
0:21:33 > 0:21:36But there's one other element to add to the avalanche laboratory.
0:21:36 > 0:21:40I need an accurate measurement of exactly how fast I'm skiing.
0:21:40 > 0:21:43So I've called in the professionals.
0:21:44 > 0:21:46Police officers Paul and James
0:21:46 > 0:21:49have brought along their super accurate speed gun.
0:22:17 > 0:22:19How did I do?
0:22:19 > 0:22:22Not bad. We don't normally approve of speeding though!
0:22:22 > 0:22:26- 36mph.- 36mph. That's not bad, eh?
0:22:26 > 0:22:29Let's have a look at what that would be like
0:22:29 > 0:22:32with an avalanche chasing me.
0:22:32 > 0:22:3436mph is pretty fast,
0:22:34 > 0:22:38but even slow slab avalanches travel at up to 80mph.
0:22:39 > 0:22:41Even with a head start, you can see
0:22:41 > 0:22:43how quickly the snow catches me up.
0:22:44 > 0:22:46Lucky for me, the avalanche is virtual.
0:22:48 > 0:22:51Jeepers! I would have been toast.
0:22:51 > 0:22:54I'm overtaken almost immediately
0:22:54 > 0:22:57and that's on a well-groomed indoor slope,
0:22:57 > 0:22:59skiing calmly with no pressure.
0:22:59 > 0:23:02So chances of outrunning an avalanche in reality?
0:23:02 > 0:23:04I'd say pretty much zero.
0:23:05 > 0:23:09There's a lesson here. Don't cause an avalanche in the first place.
0:23:09 > 0:23:11Ski hard, ski safe.
0:23:16 > 0:23:20Back in Tignes, I'm up early to rejoin the ski patrol.
0:23:20 > 0:23:24I catch a special lift with Sebastian to the top
0:23:24 > 0:23:25of the ski area.
0:23:25 > 0:23:29The slopes have to be empty for the big event we've got planned.
0:23:29 > 0:23:31It's a great privilege to be up in the mountains with
0:23:31 > 0:23:34nobody around, but there's some serious work to be done.
0:23:36 > 0:23:41These automated gas explosion blasters stop snow building up
0:23:41 > 0:23:42to dangerous levels.
0:23:44 > 0:23:47I've just stopped on the piste here, just above us
0:23:47 > 0:23:51you see these strange pipes sticking out of the mountain. That's Gasex.
0:23:51 > 0:23:55On the way to meet the patrol, it's clear the daily battle
0:23:55 > 0:23:58against the avalanche is already well under way.
0:23:58 > 0:24:01And we're just about to hear one of them go off now.
0:24:09 > 0:24:11LOUD BLAST
0:24:12 > 0:24:14Wow!
0:24:14 > 0:24:15You feel the power there,
0:24:15 > 0:24:18that's what's needed to set the avalanche off.
0:24:18 > 0:24:22And we're literally a few tens of metres from the piste.
0:24:22 > 0:24:26It shows you how close you can be to avalanche danger even on the slopes.
0:24:26 > 0:24:28Incredible.
0:24:29 > 0:24:31LOUD BLAST
0:24:31 > 0:24:32Wow!
0:24:35 > 0:24:39But the automatic snow blasters are small fry compared with
0:24:39 > 0:24:41what we've got planned this morning.
0:24:41 > 0:24:44It's 7am in the patrol hut and already the talk
0:24:44 > 0:24:47is of the snowpack - how much snow there was in the night,
0:24:47 > 0:24:50the temperature, the wind direction...
0:24:53 > 0:24:56It all adds up to the reason why we're here.
0:24:56 > 0:24:59We're going to fight avalanche with avalanche.
0:25:03 > 0:25:06Controlled explosions are used to create small avalanches
0:25:06 > 0:25:09rather than let the snow build up into something much bigger,
0:25:09 > 0:25:12more unpredictable and more deadly.
0:25:16 > 0:25:20So we're right at the edge of the snow ledge here.
0:25:20 > 0:25:25The snow patrol are making three holes down into the snow,
0:25:25 > 0:25:28they're going to drop three explosives down into those holes
0:25:28 > 0:25:30to detonate and cause an avalanche
0:25:30 > 0:25:33and then they're going to get out of here rapidly before that
0:25:33 > 0:25:36happens, which is exactly what I'm going to do now.
0:25:36 > 0:25:39Wind has caused snow to build up into a dangerous overhang
0:25:39 > 0:25:40called the cornice.
0:25:40 > 0:25:42This one is unstable and could fail
0:25:42 > 0:25:44at any time right onto
0:25:44 > 0:25:46the piste that is running directly below.
0:25:46 > 0:25:48The team need to remove the snow now
0:25:48 > 0:25:50when the ski lifts are closed
0:25:50 > 0:25:53and we know there's nobody underneath.
0:25:53 > 0:25:56We are about to witness the power of an avalanche.
0:26:14 > 0:26:18LOUD BLAST
0:26:34 > 0:26:35My heart's racing!
0:26:37 > 0:26:40If there was anyone down the bottom of that, they would be toast.
0:26:42 > 0:26:44Absolutely incredible.
0:26:44 > 0:26:47You could see there was so much snow up there with that ledge,
0:26:47 > 0:26:50now it's all gone - all you can see is rocks.
0:26:50 > 0:26:54There's only one place it went. Down as an avalanche.
0:26:54 > 0:26:58I've just witnessed my first avalanche and it was breathtaking.
0:27:00 > 0:27:04Today, we have had an insight into the power of the avalanche
0:27:04 > 0:27:08and also the ingenuity of the human beings who live with the threat.
0:27:08 > 0:27:10The machines that make the slopes safe
0:27:10 > 0:27:13and the technology that can save you if the worst happens.
0:27:13 > 0:27:15Every second counts.
0:27:16 > 0:27:20Because of this, avalanches where people get hurt are quite rare,
0:27:20 > 0:27:22so be careful, not afraid.
0:27:22 > 0:27:24The mountains are a wonderful place.
0:27:28 > 0:27:30Next time, on Fierce Earth,
0:27:30 > 0:27:32we discover the awesome power
0:27:32 > 0:27:33of the landslide.
0:27:33 > 0:27:35Leah goes out with the crews
0:27:35 > 0:27:36trying to save our cliffs
0:27:36 > 0:27:39from slipping into the sea and I go deep underground to
0:27:39 > 0:27:43witness the massive caves hollowed out in the rock beneath our feet.
0:27:43 > 0:27:45That's amazing! Wow!