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Mount St. Helens in the countryside of Washington erupts for the first time in 123 years, killing 57 people.
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00:02The slumbering volcanic peak of Mount St. Helens.
00:06In its shadow, one of America's most beautiful national forests.
00:11A magnet for vacationers seeking the great outdoors.
00:17But then, without warning, the volcano erupts.
00:23In just four minutes, the blast flattens 570 square kilometers.
00:28Huge mud flows surge down 240 kilometers of river valleys.
00:3357 people die.
00:37With all eyes on the mountain, why did no one predict such a catastrophic eruption?
00:46Now, using advanced computer simulation, we reveal why the Mount St. Helens blast took everyone by surprise.
00:56Behind natural disasters are a chain of critical events.
01:00Unravel the clues and count down those final seconds from disaster.
01:12The American Northwest.
01:15Washington State.
01:18Mount St. Helens.
01:20At 2,950 meters, the spectacular volcanic peak crowns the Pacific coast.
01:31Beneath Mount St. Helens, just 160 kilometers from Seattle, lie more than 5,000 square kilometers of national forest.
01:38And a network of three rivers fed by meltwater from the volcano's snow-capped peak.
01:44It's a picture postcard setting.
01:47A vacation is paradise.
01:49The region pulls in half a million visitors a year.
01:55Then, on March 27th, 1980, at 12.36 p.m.
02:03We are directly over Mount St. Helens right now.
02:06And there is no question at all that the volcanic activity has begun.
02:10Mount St. Helens spews smoke and ash over 1,800 meters into the sky.
02:15The volcano has woken up from a 123-year sleep.
02:23Excited by the prospect of more eruptions on their doorstep, thousands of spectators flock to the area.
02:32But scientist David Johnston, from the U.S. Geological Survey, or USGS, is worried.
02:40He's been fascinated by volcanoes since the age of 18,
02:44and thinks that this eruption is an indicator of something larger to come.
02:50He goes on TV to warn the public of the danger.
02:53It could be within hours, it could be within days, or even up to a couple of months.
02:59This is not a good spot to be standing.
03:03Johnston is only 30, but he's already a highly respected volcanologist.
03:10Local county sheriffs heed his warning.
03:14They immediately close public roads and highways within about 11 kilometers of the summit,
03:18and they force local residents and sightseers to evacuate.
03:24You're gonna have to go, and the faster the better.
03:26One time, one thing, you gotta go.
03:31March 29th.
03:33Two days later, the volcano is quiet.
03:36But a news camera crew spot a newly formed crater on the mountain summit.
03:40When USGS scientists see the images, they know that internally, the mountain is waking up.
03:47They devise a map to highlight areas that'll be affected in the event of a large eruption.
03:52They base it on the worst eruption the volcano has ever produced.
03:57A classic vertical blast.
04:03The map includes areas that will be directly affected by the blast.
04:07As well as 240 kilometers of river valleys that'll be affected by lahars,
04:13giant mudflows caused by rapid snowmelt at the volcano's peak.
04:23The finished hazard map identifies large areas of state forestry commission and privately owned land all at risk.
04:30But the USGS is an advisory body and has no power to enforce land closure.
04:38Now, the US forestry commission take action.
04:42They set up two restricted zones on their land based on information supplied by the USGS.
04:50The inner red zone is the most hazardous area.
04:54Its boundary extends up to 11 kilometers from the summit of the volcano.
04:58Only the police and scientists are allowed in here.
05:03The outer blue zone is less dangerous.
05:05Its boundaries are up to 24 kilometers from the volcano.
05:10The public is still banned, but logging company employees have access.
05:15But outside of these two exclusion zones,
05:18the public can still go into large areas deemed hazardous by the USGS,
05:22including land and river valleys at threat from lahars.
05:32Saturday, May 17th, 1980.
05:37For seven weeks, America has been watching Mount St. Helens splutter.
05:41But the big one still hasn't happened.
05:45Even so, the waiting game is national news.
05:48There are rumblings of something big about to happen in Washington state.
05:53The eruption of Mount St. Helens.
05:57Then, as quickly as it started seven weeks earlier,
06:00Mount St. Helens falls silent.
06:03To some people, it feels like the big one won't happen after all.
06:09With a hot and sunny forecast, hundreds of people from towns and cities make spur-of-the-moment decisions to
06:15head out to the countryside.
06:17Among them are two mill workers.
06:20Nineteen-year-old Danny Bouch.
06:23And his friend, 20-year-old Brian Thomas.
06:29Danny is aware of the news reports on Mount St. Helens.
06:31And he's worried about going too close.
06:35I still was pretty well convincing Brian to go to the beach.
06:38I didn't want to go up there.
06:40I was pretty sure something would happen.
06:43But Brian convinces him otherwise.
06:46They meet up with four friends.
06:49And set up camp near an old log cabin in 11 kilometers outside of the outer blue zone.
06:57Danny begins to relax when he sees that two high ridges stand between them and Mount St. Helens.
07:04The fine weather also brings out a young couple.
07:07Sweethearts, Vina Sturgen and Roald Reiton are looking forward to a weekend of camping in the great outdoors.
07:14By the time we got there it was maybe noon and it was like 85, it was great.
07:20So we set up a little camp and fish and just camp for the weekend.
07:24Build a fire, you know, it's like, do what kids do.
07:30Roald is taking few chances.
07:32He chooses a camping spot 43 kilometers outside the blue zone, 53 kilometers from the mountain.
07:39He and Venus are at a bend on the Tuttle River, one of the three rivers fed by meltwater from
07:44Mount St. Helens.
07:47The center of the mountain was 33 miles from where I was camped.
07:52I mean, we didn't go down there to see it, be around it or anything.
07:55Like, it wasn't even in the back of our minds.
07:59This far outside the exclusion zone, Roald and Venus feel completely safe.
08:07But at a spot just nine and a half kilometers from Mount St. Helens, deep inside the red zone,
08:13USGS geologist David Johnston is monitoring the volcano.
08:17It's supposed to be his weekend off, but he's covering for a colleague.
08:22Johnston sees it as another opportunity to study Mount St. Helens,
08:25the volcano that's fascinated him since high school.
08:29He's here to monitor a mysterious rock bulge that appeared on the volcano's north face four weeks ago.
08:39As he takes his readings, Johnston confirms that the bulge is growing fast.
08:45It is now over 135 meters long and 30 meters high, and it's still growing one and a half meters
08:52every day.
08:56Other USGS scientists think the bulge is just another sign of an impending big vertical eruption.
09:05But David Johnston disagrees.
09:09Based on his research, he thinks that the rock bulge is a clear sign that Mount St. Helens may erupt
09:15in a far more deadly way.
09:17Sideways, in a lateral blast.
09:237pm.
09:25Roald and Venus prepare their dinner.
09:27Fish caught that afternoon in the Tootle River.
09:30And Danny, Brian and their four friends crack open a few beers by the campfire.
09:35The friends are looking forward to a great weekend in the National Forest.
09:39A weekend they'll always remember.
09:44Sunday, May 18th, 1980.
09:48A hot sunny weekend sends vacationers into the National Forest land surrounding Mount St. Helens.
09:568am.
10:0111 kilometers outside the blue exclusion zone, Danny Bouch, Brian Thomas and four friends begin to stir.
10:08Some of the group are awake.
10:10But Danny and Brian are still asleep in their tent.
10:13They've been up drinking all night.
10:198.15am.
10:208.15am.
10:22Scientist David Johnston continues to monitor the growing bulge on the north face of the volcano.
10:28He's in the dangerous red zone, just nine and a half kilometers from Mount St. Helens, where only scientists and
10:34police have access.
10:37For the next four hours, he'll record and transmit his findings to colleagues at USGS headquarters in the city of
10:43Vancouver, Washington.
10:44Then he'll be off duty and could go to meet his girlfriend for the weekend.
10:518.22am.
10:5427-year-old graduate student, Keith Ronhall wakes up.
10:58He's been interested in Mount St. Helens since it started to show signs of life seven weeks ago.
11:05Keith is 16 kilometers to the northeast of the peak, outside the red zone.
11:10He has an unobstructed view of Mount St. Helens.
11:15I thought I'd get to go see a plume of steam and ash rising five to ten thousand feet above
11:19the summit.
11:20It would be pretty impressive, and I could say, wow, I've seen a volcano erupt, and then I could ignore
11:25it for the rest of the summer.
11:28But Mount St. Helens is quiet.
11:33There was no hint of impending activity.
11:36There was no steam clouds, there were no ash clouds.
11:40So I actually rolled over and took out my novel and started reading.
11:47At 8.32am, Keith hears shouting from other sightseers.
11:54My first thought was, oh, they're yelling at their kids to come to breakfast, get away from the cliff, don't
11:59be done your brother, that kind of thing.
12:00I said, oh, I'm near a mountain, maybe I should take a look.
12:05As he does, he sees the entire north face of the mountain, including the rock bulge, sliding down.
12:12Not flowing, not sliding like a solid block of material, but flowing like it had turned to jelly.
12:18I went, oh, I'm going to get to see an eruption after all.
12:21Then, at 8.32 and 47 seconds.
12:32Mountain Helens explodes.
12:35A huge billowing cloud of hot gas and ash blasts out.
12:39It doesn't shoot up through the mountain top.
12:42It bursts out from the mountain side.
12:47The lateral blast heads straight towards USGS scientist David Johnston.
12:52He's in the red danger zone.
12:54There's no time for David to run.
12:56He sends a radio message to base.
12:58Vancouver, Vancouver, this is it! This is it!
13:02Then, the transmission stops.
13:07The blast continues to expand, and next in line is Keith Ronholm, who's been taking photographs of the eruption.
13:17At this point, as it started to come over that ridge, I started to think that maybe it was time
13:22to get out of there.
13:24Keith Ronholm floors the accelerator and tries to outrun the blast cloud racing towards him.
13:338.33 and 58 seconds.
13:3825 kilometers from Mountain Helens, outside the blue zone, a rumbling noise wake sleeping teenagers Danny and Brian.
13:46I don't know if something, an earthquake or anything actually woke me up.
13:50But I just woke up out of a dead sleep, and I just go, Brian, let's get the hell out
13:56of here.
13:58They scramble out of their tent, but the blast of volcanic cloud engulfs them.
14:04As it hit, it just knocked me flat to the ground. It was just such a heavy force.
14:08And then all of a sudden, I could feel myself starting to shrivel up like a prune.
14:13And I could feel myself starting to burn.
14:18As the cloud disappears, Danny sees a scorched and blistered landscape.
14:25He's been badly burnt by the blast.
14:28Yet his first thoughts turn to his friends.
14:34I was wondering where everybody's at. There's five other people within shouting distance.
14:41You know, nobody's answered me. I was beginning to think I was the only one alive.
14:478.42 a.m.
14:56After searching for five minutes, Danny finds his friend Brian buried under some fallen trees.
15:04Brian reached up with both his hands at that time.
15:06And I went to pick him up, and he started screaming his leg, his leg, his leg.
15:14And I reached down to his wrist and grabbed ahold of both of his wrists and told him,
15:18I gotta help you get out of here right now.
15:21Danny frees Brian and starts to carry him to a nearby log.
15:25But his four other friends are still missing.
15:29And it was at that point, the ash started falling.
15:33And at that point, within a matter of a few seconds,
15:37I could not even see Brian's back of his head, which was only inches in front of me.
15:4810 a.m.
15:52One hour and 27 minutes after the eruption.
15:5643 kilometers outside the blue zone,
15:59childhood sweethearts Roald Reiton and Venus Durgan are fishing.
16:03Mount St. Helens is 50 kilometers away, out of sight and earshot.
16:08The young couple are unaware of the major eruption.
16:13Then, they hear the sound of a warning siren from a nearby logging company.
16:18Roald looks around to see what's causing the alarm.
16:23The old growth trees, up around the bend, we could see them shaking.
16:27Shaking, and you could just, like, see dust coming off them.
16:29And you could hear them snapping and falling down.
16:31It was like a monster coming through the forest.
16:33We didn't know what was going on.
16:35A wide torrent of mud water and trees head straight towards them,
16:39smashing the forest on both banks of the river.
16:43Roald and Venus sprint to their car.
16:49It was a beat car, man.
16:51It was like, you know, I didn't like to start all the time.
16:53You know, it's like, god damn thing, I'm cussing it, you know.
16:56And she's going, come on, come on, come on, you know.
16:58And it wouldn't start.
17:01The torrent engulfs their campsite, forcing Roald and Venus to abandon their car and dive into the swirling mass.
17:09I landed on a big log.
17:13I saw Venus drop right by me, and she went right in between them.
17:18And it, like, swallowed it up, gone.
17:22Roald shouts for his girlfriend, but Venus has disappeared under the deluge.
17:30May 18th.
17:3210.10am.
17:36Mountain Helens has been erupting for one hour and 37 minutes,
17:40covering 570 square kilometers with ash and rock.
17:44Now, mud and trees surge down the river valley.
17:49The deluge separates the young couple, Roald Reiton and Venus Durgan.
17:57The big log would go up and just, whoa, cascade right over.
18:01Bam, bam, bam, right next to you.
18:03I was sure I was going to die.
18:05Roald Reiton clings desperately to a log, but he can't find his girlfriend Venus.
18:12Then he spots something in the water.
18:14Venus!
18:18All of a sudden, I saw her arms sticking up.
18:20Just her hand.
18:21I grabbed it and hung onto it.
18:24Pulled her up as hard as I could.
18:26Hung onto her for a while. I got her all the way out.
18:29The current carries the exhausted campers 8 kilometers downriver before it subsides.
18:36Roald pulls Venus up onto the bank.
18:40But he's afraid Venus is going into shock.
18:4510.12am.
18:51After 90 minutes, the ash falling on Danny Balch and Brian Thomas starts to subside.
18:57And it was at this point that Bruce and Sue started walking up to us.
19:03Two of Danny's friends have survived the eruption unscathed.
19:09Together, they carry Brian to the log cabin in the campsite and make him comfortable.
19:17Two other friends are still missing.
19:19And Brian is in great pain.
19:21His leg has been crushed.
19:24He can't walk.
19:25Danny decides he needs a doctor.
19:29I told Brian that I had to get help for him.
19:32He didn't want me to leave.
19:34But I knew I had to.
19:35If I'd have sat there with Brian, I probably would have went into shock.
19:42He promises Brian he'll be back.
19:44And sets off.
19:47By 10.30am, hundreds of rescuers from the Forestry Service, State Troopers, National Guard and Mountain Rescue, are searching for
19:55survivors in the blast area.
20:00We went in just hoping that maybe somebody would be in a cave or a cliff or behind a mountain
20:06or possibly maybe there'd be somebody still alive in the blast area.
20:14National Guard pilot Jess Hageman flies from Fort Lewis, 105 kilometers from the blast zone.
20:21There was so much ash in the air that you couldn't see very far.
20:26Most of the time I didn't really have a clue where we were hardly.
20:30The visibility was just that poor.
20:35Look at this, it doesn't even look like the same country yet.
20:41Is that in over there?
20:4811.29am.
20:51Geophysics student Keith Ronholm survived the initial blast of the volcano, but hot ash still showers down.
20:59As the downpour starts to lessen and visibility improves, he slams his foot on the accelerator.
21:1211.30am.
21:16National Guard pilots spot two survivors staggering from the forest.
21:20Roald and Venus have survived.
21:24The rescue team makes a hazardous landing.
21:27The rotors of their helicopter scything the air just centimeters from the trunks of trees.
21:33Once Roald is on board, the pilot gives him a bird's eye view of the volcano.
21:38He goes, hey, you want to see what almost killed you?
21:40And he just spun the helicopter right around.
21:43Like whoop! And there it was.
21:45Look, the mountain was venting, was going straight up.
21:48And it was just like a huge steam locomotive, like thousands of feet up.
22:005pm.
22:02Eight and a half hours after the eruption, helicopter pilots are still working.
22:08They find Danny Bouch.
22:14Two of his friends, Bruce and Sue, have already been rescued.
22:17But two others, plus Danny's friend Brian Thomas, are missing.
22:23An hour later, at 6pm.
22:28They discover Brian dragging himself through the mud, not far from the shattered log cabin.
22:38As night falls, over 100 people are in nearby hospitals.
22:46Among them, Venus Durgan, who has lost 60% of her skin.
22:54And her boyfriend, Roald, who's fractured his feet and has severe skin abrasions.
23:02Danny Bouch suffers second degree burns to 20% of his body.
23:10And Brian Thomas has a shattered hip.
23:17Rescuers deliver tragic news to Danny and Brian.
23:20Their two missing friends didn't make it.
23:26Their bodies were found huddled together in their tent, crushed by a fallen tree.
23:39In all, 57 people die in the Mount St. Helens eruption.
23:44They are the first recorded volcano victims in the continental United States.
23:51Yet 53 of those 57 victims die outside of the red and blue danger zones.
23:57In places that the USGS and state said were safe.
24:01How did the experts get it so wrong?
24:08The consequences of the Mount St. Helens blast
24:11radiate as far away as Oklahoma.
24:14In less than five hours, volcanic ash covers three states.
24:19And within 15 days, winds push the ash around the globe.
24:29In the aftermath of the eruption, the United States Geological Survey
24:33organises 70 scientists to carry out an investigation to find out why so many people died.
24:42Now using the evidence from that investigation, and by rewinding the events leading up to the blast,
24:48we can reveal what really happened at Mount St. Helens.
24:52Advanced computer-generated simulation will take us where no camera can go,
24:57inside North America's most active volcano.
25:03The eruption of Mount St. Helens on May 18, 1980, is the first volcanic eruption on continental USA since 1917.
25:13Around the world, the science of volcanology is still in its infancy.
25:18Geologist Dan Miller is a key member of the USGS investigation team.
25:22He knows they face a steep learning curve.
25:27We had never dealt with a volcanic eruption in our lifetimes in this country.
25:31So we were basically building a boat and rowing it at the same time.
25:36His team calculate that the energy released by the blast must have been 24 megatons,
25:42over 1,500 times more powerful than the atomic blast at Hiroshima.
25:50Investigators want to see inside the blast zone, but they know a second eruption is possible.
25:59Team volcanologist Richard Waite is one of the first USGS investigators to fly over the devastated area.
26:06The expert is shocked by the scale of the Mount St. Helens blast.
26:13I just couldn't believe it. I could hardly believe my eyes, yet there's the evidence that it did happen.
26:19The blast leaves Mount St. Helens 400 meters shorter.
26:26And in place of its peak, a giant crater over one and a half kilometers wide and 600 meters plus
26:32deep.
26:36But that's not the main thing to catch the investigators' attention.
26:42What surprises them is the area destroyed by the blast.
26:46It stretches 30 kilometers to the north and west of Mount St. Helens.
26:51The south and east are left practically untouched.
26:57It means it can't have been a vertical eruption.
27:00If it had been, the blast zone would radiate out evenly, causing damage all round the mountain.
27:09I didn't have any idea what the heck had happened that could have been so destructive.
27:17The team know that 12 seismographs were scattered around the mountain at the time of the blast.
27:21But none of them transmit data.
27:24They only record data on site in the field.
27:28After such a massive blast, the chances of finding any seismographs at all, let alone any that still work, are
27:34slim.
27:36Nevertheless, five days after the eruption, investigators organize a search to find them.
27:44Meanwhile, the investigators examine photos taken by survivors.
27:51One set, taken by geophysics student Keith Ronholm, proves to be vital.
27:57His photos capture the first moments of the eruption from just six kilometers away.
28:02The sequences of photographs of the eruption of May 18 are incredibly important for scientists.
28:08Because for the most part, during the day of May 18, most of us who looked towards Mount St. Helens
28:15could see nothing but a veil of ash and dust,
28:18which obscured whatever was going on around the volcano.
28:22They confirm that the blast wasn't vertical.
28:26Instead, the blast burst through the side of the volcano, laterally, a scenario most scientists had dismissed.
28:41The blast itself was something that had never been seen before.
28:44It was on a scale not measured either at St. Helens or anywhere else, as far as I'm concerned.
28:50Investigators need to find out why Mount St. Helens erupted so abnormally, laterally instead of vertically.
28:58Investigator Dan Miller examines the data gathered by scientists in the weeks leading up to the blast.
29:04From the moment of the first volcanic activity, seven weeks before the deadly blast,
29:08USGS scientists believed any major eruption would be a conventional vertical one.
29:15Why?
29:20They knew that beneath Mount St. Helens there was a vast underground chamber of magma,
29:25and after being stable for over 100 years, it was growing.
29:32Historically, scientists expected the magma to rise via a conduit in the center of the volcano,
29:37only stopping when it hit a rock plug left by previous eruptions.
29:45As the pressure built, the magma would eventually blow out the plug like a champagne cork.
29:52The result? A classic vertical eruption.
29:57But then, four weeks before the blast, scientists saw the rock bulge forming on the mountain's north flank.
30:05According to investigator Richard Waite, the growing bulge confused most USGS scientists.
30:13It wasn't clear what was happening. I mean, the volcano spreading, what does that mean?
30:17Um, nobody knew. At first, it was thought to be just the basis of the glacier melting a bit,
30:23and then suddenly creeping out a lot faster than it had before.
30:26It took some weeks before it realized it wasn't just the glacier, it was all the rock creeping out as
30:32well.
30:34The scientists couldn't see what was happening inside the volcano,
30:37but they concluded that something was blocking the magma inside the volcano's central conduit.
30:42They believed the blot magma forced its way towards the north slope of the mountain, forming the bulge.
30:50Magma was being injected inside the volcano,
30:53sort of like inflating a water balloon inside of a birthday cake.
30:57If you were to put a balloon in there and then start filling it,
31:00it would fracture and parts of the cake would move and it would sort of swell and bulge and so
31:05forth.
31:06And that's essentially what was happening at Mount St. Helens.
31:12Most scientists believed the rock bulge would eventually collapse in a landslide.
31:16Theoretically, the landslide would bring mass down from the top of the volcano,
31:20thereby removing the plug, blocking the central conduit.
31:24No plug would result in a vertical eruption.
31:32In fact, scientists were confident enough of this theory that they went public with their prediction.
31:38They believed that the rock bulge was in all likelihood simply a forerunner of the long-awaited vertical eruption.
31:49But investigators, Miller and Waite, know that one scientist had another theory.
31:58When David Johnston first saw the Mount St. Helens rock bulge,
32:02it reminded him of a study on the 1956 eruption of Mount Bezimiany in the Soviet Union.
32:08That study documented a very rare occurrence.
32:13Rather than a classic vertical eruption, the Soviet volcano had erupted horizontally in a lateral blast.
32:22David Johnston had mentioned that there was a lot of similarities between the way Bezimiany had behaved in 1956
32:29and the way this volcano, Mount St. Helens, was behaving now in March-April 1980.
32:36Before it erupted, Bezimiany had steam explosions, earthquakes, and the development of a rock bulge.
32:44The very same things Johnston was seeing at Mount St. Helens.
32:50But Johnston's colleagues weren't convinced.
32:53Analysis of volcanic deposits showed that in the hundreds of previous Mount St. Helens eruptions,
32:58all but one had been vertical blasts.
33:02What a volcano has been doing for the last four or five thousand years is a good indication of what
33:07it's likely to do in the future.
33:10At the time, Johnston's lateral blast idea seemed too improbable to be taken seriously by his colleagues.
33:18You know, theoretical possibilities are something you talk about at dinner, but it isn't anything that dominates your life.
33:30In the aftermath of a blast, investigators realized that David Johnston was right.
33:37The rock bulge on Mount St. Helens was a precursor of the devastating lateral blast.
33:46A decision to ignore David Johnston's idea had fatal consequences.
33:52The Forestry Commission modelled the red and blue zones on the USGS hazard map
33:57based on the worst vertical eruption Mount St. Helens had ever produced in its recorded history.
34:02And not a lateral blast, as had happened at Bezimiany.
34:10Investigators now understand what happened during the blast, but they still need to find out why.
34:16For that, they need hard data.
34:20So far, their search for the twelve seismographs has been unsuccessful.
34:25They find five, but all are too badly damaged to be useful.
34:30The investigation stalls.
34:35Then, ten days after the blast, a breakthrough.
34:39Eight kilometers to the west of the volcano, investigators find another seismograph.
34:45This one has survived the blast.
34:49Seismologist Steve Malone.
34:53It recorded the initial earthquake. It recorded the blast. It recorded the debris flow going by near it.
35:00It then recorded losing its antenna as a mud flow came and yanked the antenna loose.
35:06And we could see all of those sequences in the seismic record that we were able to recover from the
35:12mud.
35:14Using data from the seismograph, investigators are now able to piece together a detailed timeline of exactly what happened during
35:22the eruption on May 18th.
35:338.32 and 20 seconds.
35:37The fragile rock bulge on the north flank of Mountain Helens collapses, causing a massive landslide.
35:43This landslide wipes away the thin layer of rock that's holding the magma in.
35:51The magma explodes at the point of least resistance.
35:54In this case, the exposed mountain's north side.
36:00The eruption releases a superheated cloud of ash and debris that travels at 1,000 kilometers per hour.
36:12It's kind of like a locomotive. We're moving at several hundred miles per hour.
36:17And this cloud sort of travel across country, sort of like rolling out a carpet.
36:24David Johnston is 10 kilometers from the volcano.
36:27In just 40 seconds, the surge overwhelms him.
36:41One minute later, geophysics student Keith Ronholm realizes that the blast cloud is barreling towards him.
36:48He races for his life.
36:51After 90 seconds, the blast has passed through the red and blue zones, flattening everything in its path,
36:57smashing trees 75 meters tall to the ground.
37:11Now at 950 kilometers per hour, the cloud of ash and debris powers across the landscape.
37:19Even the high ridges surrounding Danny and Brian's campsite are no match.
37:26The blast cloud reaches them in two minutes at a temperature of 150 degrees Celsius.
37:32It's enough to boil the sap in trees and to inflict second degree burns on Danny.
37:40Ten minutes after the eruption, the heat released by the explosion melts 75% of the ice on top of
37:48Manson Hellens, releasing some 174 billion liters of meltwater into the river valley system.
37:58The team analyzes deposits of river mud up the sides of river valleys around the volcano.
38:04They discover that even 5 kilometers from the mountain, the Lahar mudslide caused by the melting volcano's glaciers is still
38:1115 meters high.
38:14It inundates 210 kilometers of river valley, traveling at 50 kilometers per hour.
38:28It's what the Lahar picks up along the way that makes it so dangerous.
38:33One torrent of mud and water overruns a logging camp on the south fork of the Tootle river valley.
38:38It sweeps up 20,000 tree trunks.
38:43Now it heads straight for Roald Reiten and Venus Durgen.
38:53The Lahar flow surges around the bend.
39:00Even here, 50 kilometers from the volcano, its force still packs a mighty punch.
39:09It only took two minutes to destroy the whole place that we were, you know, I mean, just destroyed it.
39:17Didn't look the same after just two minutes. It was unreal.
39:22The Lahar flow finally fades away 60 kilometers from the mountain.
39:28In all, Lahars destroy 27 bridges, 200 homes, and strand 31 ships on the Columbia River.
39:38The Lahar flow the town of the hill has sunk to sea.
39:49The hills of The Runway
39:50The Mount St. Helens blast was wrong.
39:50USGS scientists accept that their model of a potential Mount St. Helens blast was wrong.
39:58the red and blue zones were modeled on a vertical eruption and not a lateral blast
40:04had they listened to david johnston and taken bezimiani as the model the hazard zones may
40:09have been more accurate and more people would have survived but one part of their prediction
40:16was right they sort of hit the nail on the head in terms of lahars and where they went
40:23and what their impacts were i mean our scientists went out and took pictures of the 21 bridges
40:28on the north fork of the toodle river before the event because we knew darn well that if
40:34the eruption occurred that most of them would be gone
40:41the usgs wanted to make 240 kilometers of river valleys into no-go areas but didn't have the
40:48power to enforce it that power lay with washington state governor dixie lee ray
40:54the usgs warned governor ray but she chose not to heed the warning so why didn't she act
41:01on their advice
41:08before the mounts and helens eruption the usgs made two major forecasts one that if an eruption
41:14occurred it would be a vertical blast they were wrong
41:24but the usgs did correctly predict that an eruption would release huge mud flows that would inundate
41:31the river valley system surrounding the volcano they warned authorities i and my colleagues were quite
41:38unhappy or at least disappointed in the fact that the state of washington chose to ignore the usgs hazard
41:45zones on their land and property and not to extend the blue and red zone concept out into their own
41:52property
41:52so on on the morning of may 18 the air some areas that could have been evacuated and could have
41:58been restricted
41:59um we're not
42:06governor ray rejected the usgs recommendations the logistical restraints of closing off large tracts
42:12of river at the start of the fishing season and the cost to the state and local economy were factors
42:18she had
42:18to consider she had a choice but governor ray chose not to close the rivers it can be done
42:25and in times of war it is done but we were not in a war situation and i had to
42:30take the information that was
42:32available to me as to how much hazard how much danger and make a decision as to whether people
42:37uh should be excluded from their livelihoods and from their homes
42:41in the months after the disaster governor ray was taken to court
42:47the lawsuit alleged that the boundaries of the red and blue zones had been based on commercial reasons
42:52not scientific advice
42:54the case against washington state was dismissed in 1985
43:01the final cost of the disaster was an estimated one billion dollars
43:08the toll on those affected is impossible to calculate
43:13on the 18th of may i in just a matter of hours i was the most terrified i've ever been
43:19in my life
43:21the most excited i've ever been in my life the most challenged i'd ever been in my life okay and
43:28and
43:28knew that i was going to die too
43:30i was going to die too
43:34danny bulge still lives in washington and now has a two-year-old son
43:38but the disaster casts a long shadow over his daily life
43:4325 years on he still takes painkillers to cope with the terrible burns he suffered
43:49he's angry that scientists didn't predict the disaster
43:55nobody was really told just how dangerous it was getting
44:00just how bad the bulge was they talked about the bulge a little bit but they did not talk about
44:07how much the bulge was growing
44:12scientists maintain that in 1980 they simply didn't have the knowledge to predict the scale of the
44:17mount st helens blast
44:21the one thing that we were really unfamiliar with and did not anticipate was a very large scale directed blast
44:29and the scale of the devastation was just
44:32well it was unprecedented literally in 40 000 years of eruptions at mount st helens the lesson at
44:40st helens if nothing else is that the worst case scenario may be exceeded
44:49it's a sobering lesson because the worst case scenarios sometimes are pretty bad
44:54and if they can be exceeded you're talking serious stuff and of course this was
45:03in the aftermath of the eruption mount st helens was declared a national monument and area of scientific
45:09interest on the ridge where geologist david johnston was killed now stands an observatory dedicated to
45:18the johnston ridge observatory houses state-of-the-art monitoring equipment
45:23that continues the young geologists pioneering work
45:33the usgs describes the 1980 eruption as a wake-up call for volcanology
45:39its investigation revealed a huge amount about volcanic phenomena and transformed their ability
45:45to predict eruptions accurately
45:54in february 2005 25 years after the fatal mount st helens eruption geologists accurately predicted the
46:02volcano would become active again
46:06it did but this time no lives were lost
46:12today the work of usgs scientists extends far outside america
46:18they currently monitor 53 volcanoes worldwide
46:22offering advice on the dangers these active peaks pose
46:27it's only a matter of time until one of these volcanoes erupts but the work of the usgs
46:33will help ensure that those who live in the shadow of volcanoes around the world will be ready
46:40so
46:55it's
46:56so
46:56it's
46:57so
46:57it's
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