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The Japanese city of Kobe is rocked by the Great Hanshin earthquake, which destroys many of its buildings. Many traditional houses collapse due to the heavy roofs and weak walls. Soil liquefaction occurs at the coastal and port areas of Kobe. 6,434 people die in what is then Japan's worst peacetime disaster.
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00:00Kobe, Japan's sixth largest city and one of its most important commercial centers.
00:07Then, one quiet winter's morning, just before dawn, disaster strikes.
00:13Suddenly, without warning, a colossal earthquake rips through the city.
00:17It topples roadways and knocks over tower blocks.
00:21In 20 seconds, Kobe is left in ruins.
00:24Over 5,500 people die.
00:27Now, using advanced computer simulations, we reveal exactly why so many died in what was meant to be the most
00:34earthquake-proof country on Earth.
00:37Behind every disaster lies a chain of critical events that decide who lives and who dies.
00:44Unravel the clues and count down those final seconds from disaster.
00:56Asia.
00:59Japan.
01:02Kobe.
01:04Home to nearly 1.5 million people, Kobe is famous for its breathtaking views.
01:10But land here is at a premium.
01:13Kobe is squeezed between the Rocco Mountains and the blue waters of Osaka Bay.
01:19The city center sits on a narrow strip of land just five kilometers wide.
01:24To the east and west lie densely populated residential areas of mostly traditional houses.
01:30And to the south, its huge port area, built on a series of islands created by dumping millions of tons
01:37of soil into the sea.
01:40It's one of the world's biggest ports, handling 71 billion dollars of cargo a year.
01:46To maximize pressure space, 160 kilometers of Kobe's modern freeway system stand on pillars above the city.
01:56Monday, January 16th, 1995.
02:01It's a bright winter's day, the temperature just above freezing.
02:06Today is a national holiday, and Kobe bustles with people soaking up the holiday atmosphere.
02:13But beneath their feet, the ground is riddled with faults.
02:17These unstable cracks in the earth, 20 kilometers below the ground, are caused by movements of the earth's surface.
02:24Japan is one of the world's most active earthquake zones.
02:28In Kobe, these faults stretch the length of the city center, along the foot of the mountains.
02:34But Kobe is lucky. Fault activity is rare here.
02:38The city hasn't seen a major quake in 400 years.
02:45Ten kilometers east of the center is the residential area of Higashinada.
02:50Most of the houses here are of traditional Japanese design with a wooden frame and ornate roof tiles.
02:56In one of them, built 50 years ago, lives 59-year-old Yukiko Shona.
03:01She shares her home with her son Satoshi and her dog.
03:06Her five-year-old granddaughter is staying with them for the holiday.
03:11Yukiko has lived in Kobe all her life.
03:14Her sole experience of earthquakes is just a couple of minor tremors.
03:21Earthquakes were something tiny.
03:23I can't even recall anything falling from the shelves.
03:26So I didn't think earthquakes were anything to be scared of.
03:3430 kilometers east of Kobe is the Osaka earthquake observatory.
03:39Here, scientists monitor part of a network of thousands of seismic sensors spread all over Japan.
03:46Tonight, Toshio Arimoto is on duty with a colleague.
03:51In 21 years, he's monitored several major earthquakes across the country.
03:56But today, it doesn't feel like a proper work day.
04:02Because it was a public holiday, I really felt like it was a day off.
04:06And I wasn't expecting anything unusual at all.
04:116.26 PM.
04:14Their quiet shift is suddenly interrupted.
04:16An Earth tremor, measuring 3.6 on the Richter scale, triggers the sensor network.
04:24Arimoto isn't phased.
04:26Japan clocks up a thousand earthquakes a year.
04:29And this one's tiny.
04:31Too small, even to rattle the windows.
04:3723 minutes later, ground shaking triggers the sensor network again.
04:41But this tremor is smaller still, measuring just 2.5.
04:47The sensors reveal that the tremors originate beneath the Akashi Channel,
04:52which separates Awaiji Island from the mainland.
04:55It's 15 kilometers southwest of Kobe.
05:00In Kobe City, people are oblivious to the tremors.
05:09Shinchu, 400 kilometers northeast of Kobe.
05:13Tour bus driver Yoshio Fukumoto leaves town, heading south.
05:20He's been driving buses for 30 years.
05:25I like driving, and in those days it was cool to be a tourist bus driver, so I really enjoyed
05:30it.
05:30Shinchu, 400 kilometers.
05:32Shinchu, 400 kilometers.
05:36Fukumoto's destination is Kobe.
05:39It's an overnight trip scheduled to take 12 hours.
05:496.55.
05:50A third tremor.
05:52This one, a 1.5.
05:54The scientists are surprised to see three tremors in a matter of minutes.
05:58But Arimoto is still not alarmed.
06:03From the local seismic activity at the time, it really was unimaginable that a huge earthquake could occur in Kobe.
06:13In Yukiko Shono's home in Kobe, her granddaughter develops a fever.
06:20Yukiko rings her daughter, who agrees that the little girl should go home.
06:26Yukiko will not have her granddaughter staying with her tonight.
06:3411.49 p.m.
06:37After nearly five hours of silence, a fourth tremor shakes the Akashi channel.
06:42On average, there are five tremors exceeding magnitude 1.5 in a year.
06:46There have now been four in just under five and a half hours.
06:5329-year-old Satoshi Shono keeps his mother Yukiko up past her bedtime.
06:57He's keen to show her his latest gadget, a laptop computer.
07:05We stayed up chatting for quite a while that evening.
07:09Then it turned midnight and he said,
07:11You should go to bed, Mum.
07:12I'll have to stay up until about 2.
07:15Good night.
07:20Tuesday, January 17th, 5.45 a.m.
07:24Tour bus driver Yoshio Fukumoto is just 15 kilometers from the center of Kobe.
07:31Just three passengers remain on board.
07:36He's on the Hanshin Expressway, a 40-kilometer-long four-lane elevated freeway that runs right through Kobe.
07:45It's designed to be earthquake-proof, but like the rest of the city, it's never been put to the test.
07:53Fukumoto soon expects to be heading back to his family in nearby Kyoto.
08:02But then, after nearly six hours of inactivity, the ground beneath the Akashi Channel begins to move again, triggering the
08:10sensors in the earthquake observatory in Osaka.
08:12This time, it's more than just a tremor.
08:26January 17th, 1995.
08:305.46 a.m.
08:33At the fire station on Port Island in the Japanese city of Kobe, firefighter Makoto Fuji works the early shift.
08:41He's been on duty at the station for over 20 hours.
08:475.46 and 58 seconds.
08:51Fukumoto's routine journey takes an unexpected turn.
08:55Everything begins to shake violently.
09:03The freeway started to weave.
09:06I'd seen something like this in the movies, but I never thought I'd see the real thing.
09:12It's like driving on waves.
09:14I couldn't see properly.
09:16Couldn't focus because of the bouncing.
09:224.5 kilometers west of Fukumoto's bus, 59-year-old grandmother, Yukiko Shono, waits suddenly as the ground trembles beneath
09:31her house.
09:33At first, it shook like this, and I thought, it's an earthquake, a strong one, and then it stopped.
09:41And I thought, okay, it's just a tiny tremor.
09:44For a second, everything seems fine.
09:49It seems really weird, but there wasn't any sound.
09:55Then, Yukiko Shono's world turns upside down.
10:11At the Port Island fire station, the earth begins to shake.
10:21It went right through my body. It felt as though the building would tear itself apart.
10:31Chairs and things on the desk crashed to the floor.
10:33These days are broken, the other walls are laying in the area, and they're still walking down the roof.
10:34It took them, and they take them all.
10:35Yikes.
10:35What could you say to this?
10:36Go-bye is in the grip of a massive earthquake.
10:38A security camera at the regional office of TV channel NHK,
10:42captures the violent shaking.
10:44It wakes a technician asleep on a camp bed.
10:4918 km away, on the swaying freeway, Fukumoto's bus could go right through the barriers and
10:55over the edge.
10:56He slams on the brakes, but just when the danger seems past, the road begins to move
11:01again.
11:03I pulled on the handbrake, and at that moment, the road in front of me just fell away.
11:13I really thought we'd fallen off the edge.
11:19I was paralyzed with fear.
11:23At the Port Island Fire Station, Makoto Fuji looks outside.
11:28He sees something incredible.
11:30A flood of water spurts up through gaping cracks in the ground.
11:38I didn't know what to think.
11:42Maybe this is a crack and the island is going to split in two.
11:45Or maybe it was a big water pipe that had broken under the ground.
11:51I just couldn't work it out.
11:5630 km away, in the Osaka Observatory, Toshio Arimoto races to find the origin of the quake.
12:04It read, Awaji Island, magnitude 7.2.
12:10Awaji Island sits on the edge of the Akashi Channel, just 15 km from Kobe City.
12:15Arimoto is staggered.
12:17For the first time in four centuries, a massive earthquake has struck the Kobe area.
12:265.47 and 12 seconds.
12:29Just 14 seconds after the violent shuddering began, the earthquake subsides.
12:34Yoshio Fukumoto holds his breath.
12:37His bus teeters on the edge of the shattered freeway.
12:40The front wheels hang over a 15-meter drop.
12:44He's terrified that it will plunge to the ground.
12:46He must get the passengers off the bus.
12:58Yukiko Shono, trapped in the rubble of her home, gradually regains consciousness.
13:03But she's so dazed, she doesn't even realize where she is.
13:08I felt pain, as though my whole body had been shattered.
13:13I thought I had had a car accident, got hit by a car, and my body was paralyzed.
13:19That's what I thought, it was a car accident.
13:26Now in Kobe's residential areas, there's a deadly new hazard, fire.
13:32Hundreds lie trapped in the collapsed remains of their traditional wooden houses.
13:40Dawn light reveals the vast scale of the disaster.
13:44The quake knocked tower blocks to the ground.
13:49Toppled road bridges and flattened entire neighborhoods of traditional Japanese houses.
13:55Thousands of people lie dead and dying in the city's shattered remains.
14:01Under her crushed house, Yukiko Shono lies trapped and badly injured.
14:07The temperature is just above freezing.
14:10If rescuers don't come soon, the alternatives are grim.
14:14Freeze to death or be burnt alive.
14:22A magnitude 7.2 earthquake rips apart the Japanese city of Kobe.
14:27Thousands lie trapped and dying under wreckage.
14:32On the Hanshin Expressway, a tour bus narrowly escapes disaster.
14:36After getting his passengers safely off the bus, driver Yoshio Fukumoto is desperate to tell
14:42his company in Kyoto what's happened.
14:47So I phoned the office and said,
14:49the Hanshin Expressway has collapsed.
14:51The bus is just hanging off the edge.
14:56He told me to stop joking.
14:58Maybe it was a bit too early in the morning for him, but he sounded annoyed.
15:05The man tells Yoshio to go back and retrieve the bus's legal documents in case the bus falls over the
15:12edge.
15:15The guy just didn't understand what had happened.
15:22It was hard to believe.
15:28Dutifully, Yoshio returns to the precariously balanced bus.
15:33He inches towards the front and retrieves the documents.
15:40In the dawn light, Fukumoto takes pictures of his remarkable escape using a disposable camera.
15:49The way it was sticking out looked completely different from when we were up there.
15:53It was much more scared to look up from beneath, and I really wondered how I'd survived.
16:01It's a miraculous escape.
16:04Fukumoto walks away from his brush with death without a scratch.
16:124.5 kilometers from the stranded bus, 59-year-old Yukiko Shono isn't so lucky.
16:19She's been crushed beneath the wreckage of her home for over two hours.
16:26I couldn't breathe, and I was choking and sweating.
16:29I thought the only release from this agony would be to die.
16:33I wondered how I could kill myself.
16:40Kobe's emergency services struggle to cope with the scale of the disaster.
16:51Emergency vehicles find it almost impossible to move around the city's debris-clogged streets.
16:588.30 am.
17:00Yukiko's daughter, Kumiko, arrives in her mother's traditional neighborhood with her husband.
17:06Her own more modern home survived the quake.
17:09She and her little daughter escaped unhurt.
17:13But she's horrified to find that where her mother's house stood is just a shattered pile of timber and roof
17:19tiles.
17:21She realizes her mother and brother must lie beneath the tons of debris.
17:27At that point, I thought they were probably dead, because I couldn't believe a person could survive under that rubble.
17:34Ruptured gas mains fuel fires raging across the city.
17:43But the quake also breaks many of the water mains, leaving firefighters helpless in the face of the inferno.
17:49They pump water straight from the sea, but it's a frustratingly slow process.
17:57There was no water, and having no water at the fire was deadly.
18:04I just felt really helpless.
18:06Everything I had learned before was no use at all in the earthquake.
18:142.30 pm.
18:15In the region where Yukiko Shono lives, many of the traditional wooden houses are ablaze.
18:21And the fires are spreading.
18:24She becomes increasingly desperate.
18:26I was in such agony.
18:29I couldn't move my right arm at all because it was trapped.
18:32But I found this piece of wood.
18:34With my left hand, I started to make a banging noise.
18:42Outside, Yukiko's daughter hears something.
18:44It's not her mother, but her mother's dog.
18:50Komiko is certain the dog is trying to tell her something.
18:59She barked and stopped, barked and stopped, and kept staring at my face.
19:05Then she barks again, and when she stops, I can hear a tapping noise.
19:14So I called out, mother, mother, and we heard a tapping response.
19:19And we realized she was still alive.
19:26Komiko finds some construction workers.
19:28They help her dig towards the sounds of the tapping.
19:38It's slow work.
19:39One wrong move, and the wreckage could crash down and kill her mother.
19:49Two hours later, they finally reach Yukiko.
19:53She's been buried for ten hours.
19:55Her right leg is paralyzed.
19:57Her hip is broken.
19:58But she is alive.
20:08Finding her mother gives Komiko new hope.
20:11Her younger brother, Satoshi, could be alive too, somewhere under the debris.
20:17She calls out, but he doesn't answer.
20:21They start to dig again.
20:27Five hours later, they find him.
20:30But it's too late.
20:38When they checked my brother's pulse, they told me he didn't make it.
20:50It was the most shocking thing that's ever happened to me.
20:55That evening, Komiko has to break it to her mother that her beloved son is dead.
21:00He was just 29 years old.
21:04So my daughter told me that Satoshi didn't make it, and I couldn't speak.
21:10I just said,
21:13I see.
21:18I cried underneath my quilt after she left,
21:21making sure that my tears couldn't be seen from the outside.
21:27Yukiko Shono's son is just one of 5,502 people killed.
21:33More than 235,000 people are homeless.
21:37More than 100,000 buildings destroyed.
21:40The quake wrecks electricity and water systems.
21:44The damage tops $150 billion.
21:47It's the world's most costly disaster.
21:50It overwhelmed the city's emergency services.
21:53And help from the national government took almost two days to arrive.
22:00Japan prides itself on its ability to build earthquake-proof buildings.
22:04So why does their city lie in ruins?
22:07And why didn't scientists predict a major quake?
22:13The population of Kobe wants answers.
22:1824 separate teams of experts embark on a wide-ranging investigation of the disaster.
22:25Seismologists will explore the quake itself,
22:27while engineering experts probe the failure of buildings and structures.
22:32Now, by rewinding the disaster and by going deep into the investigation,
22:37we reveal what really happened at Kobe.
22:39How so many people died and why the quake left the city looking like a war zone.
22:45Advanced computer simulation will take us where no camera can go,
22:49into the heart of the Kobe disaster.
23:00Earthquake expert Professor Charles Scorthorne is one of the first on the scene.
23:04By a remarkable coincidence, he was attending an earthquake conference
23:08just 30 kilometers from Kobe and actually felt the quake.
23:12He quickly realizes that this is an earthquake of colossal proportions.
23:18This was the most significant earthquake of the second half of the 20th century.
23:22This was a direct hit on as modern a society as you can have in the world,
23:28and it was totally devastated.
23:34Japanese experts working with him cannot believe the scale of the destruction.
23:39My Japanese colleagues really were having a difficult time
23:43because they just did not expect this.
23:47It may be like Americans on 9-11.
23:49This was something that was shocking.
23:58Earthquakes are a fact of life in Japan.
24:0113 major quakes have hit the country in the last 100 years,
24:04killing over 150,000 people.
24:08The country sits on the boundaries of four massive tectonic plates.
24:15As these plates shift, the movement triggers quakes along a network of thousands of fault lines under Japan.
24:23Kobe lies 200 kilometers north of the nearest plate boundary, called the Nankai Trough.
24:29So major quakes in the region are very rare.
24:32But this time, tectonic movement at this boundary is big enough to reach Kobe.
24:37Seismic equipment reveals that the quake is magnitude 7.2,
24:42powerful enough to be picked up by sensors on the other side of the planet.
24:47The quake scores a direct hit on Kobe City.
24:50But scientists are puzzled to find that its original epicenter is 15 kilometers away.
24:58It doesn't seem to make any sense.
25:00This should put Kobe outside the zone of severe damage.
25:05So what did cause the destruction in Kobe City?
25:13January 17th, 1995.
25:16A magnitude 7.2 earthquake devastates the Japanese city of Kobe.
25:22The quake's epicenter is under Awaji Island in a fault well known to seismologists.
25:26But a quake here should only cause serious damage in Awaji.
25:32It cannot explain the scale of the devastation 15 kilometers away in Kobe.
25:38This could only be caused by a fault rupturing directly under the city.
25:44Experts analyze hundreds of sensor readings from the Kobe quake and discover a shocking fact.
25:51There's a subterranean fault line beneath the Akashi Channel that scientists were completely unaware of.
25:58Previous surveys didn't pick it up.
26:00It's not large, but it links the Awaji fault to a fault directly under Kobe.
26:12January 16th, 11.49 PM.
26:15The series of small quakes that Toshio Arimoto sees in the Osaka Earthquake Observatory are not just harmless tremors.
26:23It's the ground on either side of the fault line beginning to shift 15 kilometers beneath the surface of Awaji
26:29Island.
26:315.46 AM and 52 seconds.
26:34Scientists are now certain that the violence of the Awaji Earthquake triggers a chain reaction through the undiscovered fault.
26:42The quake now races along this fault towards Kobe at 9,000 kilometers per hour.
26:49Six seconds later, the fault under the city ruptures.
26:52It's a direct hit.
26:57The earthquake goes off with the energy of a 65 kiloton nuclear bomb.
27:06Even if Arimoto had known about the undiscovered fault line,
27:10the initial tremors don't necessarily indicate that a quake is imminent.
27:18I suppose if you look at it afterwards, you could see it as a foreshock.
27:27But there's no way to predict there's going to be a huge disaster from just observing a bunch of tremors.
27:39Even today, it remains impossible to predict an earthquake.
27:46It's clear how the quake scores a direct hit on Kobe.
27:51Now investigators must focus on another puzzle.
27:55Why did more than 5,000 people die in the disaster,
27:59in a country that's renowned for building earthquake-proof cities?
28:05When investigators analyze the pattern of fatalities,
28:08they discover that the overwhelming majority of deaths occur in the city's suburbs.
28:16Here, whole streets of traditional timber-framed Japanese houses simply collapse.
28:224,900 of the quake's victims die in this type of house.
28:28The investigators' first priority is to find out why.
28:33They examine the design.
28:36They find that these types of houses are simply constructed using a series of timber supports.
28:42But, topping this lightweight structure is an ornate tiled roof.
28:48The Japanese house has a heavy roof, so you're supporting tons of roofing on really just little spindly columns.
29:01One of these roofs weighs two tons.
29:07In a modern timber house, solid walls help to brace the wooden supports.
29:11But investigators discover that walls in these older houses are made of plaster and bamboo,
29:17which have no structural strength.
29:21The unbraced posts provide the only support for the heavy roof.
29:26When the earthquake strikes, there is nothing to stop the structure swaying,
29:31and then caving in.
29:33It's called a pancake collapse.
29:36As the heavy roof pancakes down, it crushes the floors below,
29:40and anyone unfortunate enough to be inside.
29:48It causes nearly nine out of ten of the deaths in Kobe.
29:54What killed everyone in Kobe, almost everyone, was the Japanese house.
29:57And the Japanese house is a killer.
30:01But if the structure is so weak, why top them with such heavy roofs?
30:06The investigators discover an appalling irony.
30:09The heavy roofs are built to resist a natural disaster.
30:13Not earthquakes, but typhoons.
30:18On average, Kobe is hit by more than two of these destructive tropical storms every year.
30:295.46 and 58 seconds.
30:32Yukiko Shono's typhoon-proof house is no match for the devastating power of the Kobe quake.
30:41The house simply collapses, crushing her and killing her son.
30:47The heavy roofs, the very feature that might save lives in a typhoon, prove a death sentence in an earthquake.
30:58While the death toll is highest in the traditionally built suburbs, investigators find ample evidence of severe structural damage elsewhere
31:05in Kobe city.
31:09And investigators are puzzled why so many of Kobe's modern structures also collapse.
31:15These should be constructed to building codes specifically designed to withstand a major earthquake.
31:27There is no more potent symbol of this failure than the collapsed Route 3 of the Hanshin Expressway.
31:34It's 40 kilometers long, elevated above ground level by hundreds of concrete pillars.
31:39The quake damages or destroys over half of them.
31:44It also topples 26 of its 1,304 sections of roadway.
31:49Built in 1969, it was a key transport artery carrying more than 180,000 cars a day.
31:58Its loss cripples Kobe's transport system.
32:02The Japanese Ministry of Construction orders an investigation.
32:08Engineer Hirokazu Emura is one of the principal investigators.
32:12The amount of damage, astounding.
32:16The Japanese Ministry of Construction is the highest seismic force in the world.
32:17Honestly speaking, we did not expect such a total collapse of the bridges.
32:22Because we design bridges with the highest seismic force in the world.
32:28So we had been thinking that our structure is the strongest.
32:34Emura and the team are mystified.
32:38The Hanshin was designed to withstand a magnitude 8.1 earthquake.
32:4222 times as powerful as the magnitude 7.2 quake that decimates it.
32:47The public clamors for answers.
32:50Were corners cut during the Hanshin's construction?
32:53The first criticism we heard from the citizens
32:58is there could have been mistakes made in the construction.
33:03Emura knows that Japanese civil engineering is under the microscope.
33:10We wanted to show citizens that we did not make any mistakes in the construction.
33:18The team begins a forensic examination.
33:21One of the key failures is in the eastern suburbs,
33:24where Yoshio Fukumoto's bus had a lucky escape.
33:31The whole section of roadway has simply fallen off its pillar.
33:35It leaves the bus teetering on the very edge of a 15-metre drive.
33:43Investigators know this should not be possible.
33:45Each 52-metre-long section is securely bolted to the pillars
33:49by cast-iron fixings 190 millimetres thick.
33:53But when they check the fixings, they discover that the earthquake's violence has sheared them apart.
34:01It leaves the slabs of road resting loosely on top of the pillars.
34:06But the team still can't understand why the sections of road fall.
34:10A single 965-ton slab, like the one beneath Fukumoto's bus,
34:16would have to slide 120 centimetres to drop off its pillar.
34:20They're convinced that the earthquake alone could not cause such extreme movement.
34:24In a moment, Emura and the team re-inspect the road sections.
34:28Then, on the faces of the 33-millimeter thick steel girders that support the roadway,
34:33they spot something.
34:36The thick steel has been smashed and bent.
34:40The investigators realize this damage is caused by the 965-ton girders crashing into each other.
34:47These violent impacts act like gigantic hammer blows that force the slabs of road over the edge.
34:555.46 and 58 seconds.
34:58As the quake begins, the steel fixings supporting the slabs of road snap.
35:04The sliding slabs crash together, pushing one another across the tops of the pillars.
35:10Fukumoto is now driving on a road surface that slides back and forth beneath his bus.
35:21Fukumoto screeches to a halt.
35:24His front wheels rest on a road section, teetering on the edge of its pillar.
35:29Then it slips the last few centimetres and crashes over the edge.
35:37If Fukumoto had stopped a few metres further on, his bus would have plummeted 15 metres.
35:43Chances of survival would have been slim.
35:48The way it was sticking out, I really wondered how we survived.
36:02But Fukumoto and his passengers are even luckier than they thought.
36:06Had the quake happened just minutes later, he would have travelled 4.5 kilometres further along the Hanshin.
36:13Here, the quake topples a stretch of roadway more than half a kilometre long.
36:17And it looks almost like a giant child's toy that's laid over on its side.
36:23The girder fixings here are intact.
36:25This time, the quake has fractured the concrete pillars themselves.
36:29How did they fail?
36:32Imura and the team inspect the pillars.
36:35They find that three layers of steel bars reinforce them.
36:39It's a routine building technique.
36:43The two outer layers run all the way from top to bottom.
36:46But the inner layer stops 1.5 metres above ground level.
36:52Photographs taken during the investigation show these shorter bars sticking out of the shattered concrete.
36:58This is exactly where the pillars fail.
37:07As the ground shakes, the roadway begins to sway.
37:11Its vast weight puts immense stress on the pillars.
37:15Seconds later, the pillars snap at their weakest point, where the inner layer of reinforcing bars ends.
37:22The heavy roadway crashes to the ground.
37:27Investigators work out that if the inner reinforcing bars had not been made,
37:31short like this, the Hanshin might have survived the quake.
37:39It's clear that major elements of the Hanshin structure were highly vulnerable.
37:44But it was built to strict building codes introduced in 1964.
37:49Codes that should have ensured it could withstand a much bigger quake.
37:53So why did they fail?
37:54Sensor data reveals that the epicentre was unusually shallow, just 15 kilometres below the surface.
38:01That made the ground acceleration, the violence of the movement, especially severe.
38:07But in 1964, experts had very little data on this phenomenon.
38:12Investigators discover that the ground acceleration in the Kobe quake was more than twice as violent as the 1964 building
38:19codes allowed for.
38:25It's this that causes such severe damage to the Hanshin and so many of Kobe's other modern structures.
38:32Now we knew from the results that the design method at the time was not correct.
38:41The Japanese government updated the codes three times after the Hanshin was built.
38:46But the new rules only applied to new structures, not existing ones.
38:56Investigators are starting to find out why the Kobe quake is so devastating and so deadly.
39:05How traditional Japanese houses are a death sentence for thousands.
39:09Why so many modern structures are annihilated.
39:12And how the quake scores a direct hit on the city, leading its citizens seconds from disaster.
39:2720 seconds from disaster.
39:29An earthquake strikes the northern tip of Owaji Island.
39:33It tears open a previously unknown fault nearby.
39:36Now the quake races along the fault at 9,000 kilometres per hour and heads straight for Kobe.
39:4414 seconds to disaster.
39:46The fault right under the city ruptures with cataclysmic force.
39:52It shakes the Hanshin expressway like a rag doll.
39:56Still fixing sheer and whole sections of the road crash to the ground.
40:00It leaves Fukumoto's bus hanging over an abyss.
40:034.5 kilometres away, it snaps inadequately reinforced concrete pillars, downing over half a kilometre of roadway.
40:12And in hundreds of traditional houses to the east and west, it kills nearly 5,000 people as their heavy
40:18roofs crash down on top of them.
40:23Just 20 seconds after the first seismic activity, the earthquake subsides.
40:32It leaves the city of Kobe a shattered, blazing ruin.
40:38But the investigators have one puzzle still to solve.
40:43What caused the widespread subsidence in the devastated port area?
40:51Could the mysterious eruptions of muddy water reported by witnesses be a crucial clue?
41:03The Kobe quake savages the city's economy.
41:08The worst impact is felt in Kobe's vital docks area.
41:13It's so badly damaged, it's out of action for over two years, wiping out some 40 billion dollars of Kobe's
41:19vital trade.
41:24Investigators find that the damage here looks different from the rest of the city.
41:29In places the ground has dramatically subsided.
41:33And 9 kilometres of concrete dockside has fallen into the sea.
41:41Investigators learn that eyewitnesses like firefighter Makoto Fuji report a flood of water during the quake.
41:47Not from the sea, but erupting out of the ground.
41:52It was about a meter high and maybe 10 metres wide.
41:56At first, when I saw the wall of water bursting through the ground, I didn't know what to think.
42:03It's a crucial clue.
42:05Investigators suspect that Fuji witnessed an unusual phenomenon that can be caused by major quakes.
42:14Niigata, in north central Japan, 1964.
42:17This original film shows a slurry of muddy water erupting out of the ground during a quake.
42:23It was the first time this phenomenon had been captured on film.
42:31It undermines the foundations of buildings, causing severe damage.
42:35The phenomenon is now known as liquefaction.
42:38It happens when a quake strikes ground saturated with water, just like the land beneath Kobe's Port Island.
42:48Port Island is built on land reclaimed from the sea in Kobe's harbour.
42:51However, city authorities dumped 80 million cubic metres of sandy soil from the Rocco Mountains over an area of 4
42:58.5 square kilometres.
43:00The 14-year project was completed in 1980.
43:04The landfill area would usually be a perfectly reliable base for buildings.
43:09But, just below the surface, it's loosely packed and saturated with water.
43:215.46am and 58 seconds.
43:24When the earthquake strikes, the shock waves shake Port Island's loose, sandy soil.
43:31If you take a can of coffee, coffee grounds, and you tap it, you know the coffee grounds will settle.
43:37Well, sand is very much the same way, and if the earthquake taps it, that ground will settle.
43:44The gaps between the loosely packed sand grains are filled with water.
43:49The quake compacts the grains tightly, forcing the water up towards the surface under terrific pressure.
43:57What Fuji sees is not a broken water main, but a flood of liquefied soil.
44:05Investigators conclude that wide-scale liquefaction of reclaimed land is what destroys much of Kobe's port.
44:19In the wake of the disaster, city authorities rebuild Kobe using the latest earthquake-proofing technology.
44:25They spend $6.8 billion on the port alone, rebuilding the dot walls with much deeper foundations to resist any
44:33future quake.
44:34Modern houses with solid walls and light roofs replace the flattened neighborhoods of traditional homes.
44:40And the elevated expressways get a $3 billion upgrade, with more reinforcing bars and steel sheathing on the columns.
44:51Yoshio Fukumoto still drives buses. His lucky escape made him Japan's most famous bus driver.
44:58But news of earthquakes still sends chills down his spine.
45:06When I see earthquakes today, I feel a raw pain.
45:11I'm very frightened of earthquakes.
45:19Yukiko Shono still lives in Kobe, on the site of the house where her son Satoshi died.
45:31Yukiko Shono gives public talks, advising people how to be prepared if an earthquake strikes.
45:40If that saves even one more life, the next disaster, this is the least I can do for those who
45:47died.
45:50If there is a world beyond this one, when I get to where my son is, I can at least
45:57smile and proudly tell him,
46:00Mummy has done well.
46:05After the Kobe disaster, Japan's government introduced a national disaster strategy
46:11to ensure fast response by rescuers and equipment in the event of a major quake.
46:17When a magnitude 6.8 quake hit the city of Nagata in 2004,
46:22special rescue teams were on the scene within hours.
46:26The Kobe disaster forced the Japanese to reappraise just how earthquake-proof their cities really are.
46:32They can't change their earthquake-prone country, but the lessons learned from Kobe
46:36will save thousands of lives when another major earthquake strikes.
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