Why Can't We Predict Earthquakes? Horizon

It's Sunday 11th May, 2008.

For millions of people, it's just another ordinary day.

Meanwhile, at earthquake monitoring stations around the world,

there's nothing special to report.

What no-one knows is that 24 hours later,

an extraordinary natural disaster is going to strike.

TV: A massive rescue operation is under way...

..7.28 this morning, sending shock waves around Asia.

..a magnitude of 7.8 struck Sichuan Province...

An enormous earthquake tears into Sichuan Province in Western China.

Over 50 million people are affected.

Five million lose their homes and 70,000 die.

And all because science can't answer what seems like a simple question.

In the last 100 years, earthquakes have killed over a million people.

And with the growth in the world's population

scientists predict that this century might see ten times as many deaths.

So why can't we work out when and where the next big quake is going to happen?

Well, the more work we do on earthquake prediction

the more difficult it seems it's going to be.

You start to think you see patterns and understand them

and then when you try to play the game forward

and look for those patterns, it just hasn't ever panned out.

If you were a seismologist and you knew how to predict earthquakes,

er, you've arrived.

So why is earthquake prediction so difficult?

And what is science doing to overcome this force of nature?

If you want to know about earthquakes, this is the place to come -

California.

# They tell me the faultline

# Runs right through here... #

American's golden state lives in the constant shadow of an enormous earthquake,

and because of this they throw more money into studying these disasters than anywhere else.

# They tell me the faultline

# Runs right through here. #

At the heart of this effort is the United States Geological Survey,

the nerve centre of earthquake monitoring.

This is a map showing the global earthquakes of the last week.

Any time you look at this picture there's going to be aspects of it that are gonna look a lot like this.

You're gonna see this distribution down California

because this map is showing smaller magnitude earthquakes in California.

The red shows that we've just had an earthquake, this is at the Northern end of Japan.

There's usually something in Japan every week that's large enough to show up here.

The South Pacific is one of the active areas of the world right now.

You'll see a few things spread around, somewhere through Asia essentially all the time.

For seismologists like Lucy Jones,

it's no longer a mystery why the earth suffers so many quakes.

The tectonic plates that make up the world's crust

grind against each other, building up huge amounts of stress.

The stress produces cracks known as faults.

Wherever there's a fault, there might one day be an earthquake.

We know that earthquakes happen

because stress builds up in the crust

and finally you overcome the friction and you slip suddenly.

Actually, an analogy is snapping your fingers.

When you snap your fingers you have two surfaces in frictional contact.

But, all right, now I'm trying to say what micro-second they're going to move on

and that's going to be exactly what point the friction is overcome.

That's, er... There's a lot of processes going on there.

But even though scientists know how and where earthquakes happen,

the question they can't answer is the one that matters most.

So on May the 11th did you think there was going to be a big earthquake in China?

No. There's nobody who on May 11th said there's gonna be an earthquake.

There are plenty of people on May 13th said "I really did know this two days earlier."

It's a far cry from the picture of just couple of decades ago.

This is Parkfield,

a tiny hamlet in the middle of California.

Few people ever come here, and even fewer stay.

But this village lies on top of the infamous San Andreas Fault,

and once looked like it held the key to understanding earthquakes.

It all began when a team of geologists led by John Langbein

noticed something unusual about little Parkfield.

It was, er, in the '70s and early '80s it was recognised

that there was a sequence of magnitude six earthquakes

that repeated the same stretch of the San Andreas Fault

every 20-odd years and it didn't take too much imagination

to extrapolate and say the next one ought to be in the late '80s.

The village had always suffered from earthquakes, but these quakes followed a very distinct pattern.

Langbein's team decided to use Parkfield for a bold and unprecedented experiment.

To see what happened to the ground before an earthquake struck.

Estimating that the quake would occur between 1987 and 1993,

scores of geologists descended onto Parkfield.

They came to town and they set up shop with instruments,

and they're sort of hidden away and tucked away

so they're not that obvious but there's a lot of them out there.

And the idea was to have the instruments ready to catch the next earthquake red-handed.

Well, what you're hoping to see, the analogy is a stick breaking,

so in the long term you're bending the stick,

you see it, er, deform

and then maybe just before the stick actually goes snap

you'll hear "crack crack crack" or something like that.

Now that they had narrowed down the time window

and knew where it was going to strike,

this was science's best chance yet to see an earthquake in action.

Millions of dollars flooded in to fund the research.

All they had to do now was just sit and wait.

This ranch house is the high-tech outpost for a team of scientists from the US Geological Survey.

Every morning they check sophisticated sensors,

looking for signs that the Earth is ready to rumble.

So how many instruments are buried here in Parkfield?

You know, it's a little hard to count.

There's probably about two to three hundred.

We had some creep meters that measure fault slip,

some geo-chemical experiments,

strain metres, pole positioning system.

-TV:

-And on the fault line itself, TV cameras are constantly recording.

The instruments may provide a perfect...

As 1993 approached, excitement mounted amongst the geologists.

-TV:

-For five years scientists have been preparing this experiment

for the quake of '93. Now that it's built, they're hoping it will come.

But then, 1993 passed without incident.

'94.

'95.

'96.

There was still nothing.

Our guess was basically, what you'd call...

um, ambitious or optimistic.

It wasn't until September 28th 2004

that the earthquake finally struck,

and when it came, it wasn't what the scientists were hoping for.

It was like the fault was quiet quiet quiet

and then it broke,

and it was sort of, it was a fairly negative result.

You know, we were sort of waiting to catch that precursor

with all these instruments, and nothing happened.

Instead of finding signals that might predict an earthquake,

all that the Parkfield experiment seemed to prove

was that these natural disasters

were far more complex than anyone had ever imagined.

You know it was sort of taken as a negative result

and some people were saying "Time to put the nail in the coffin.

"Earthquake prediction is dead."

And I think that's a bit extreme.

One possibility is that earthquakes are different.

In '66 there was quite a large foreshock and in '34 there was quite a large foreshock

and in both of those cases the quake started up here and went that way.

And in 2004 there was no foreshock and it started in the South

and went the other way. So earthquakes are complicated.

Many people thought that Parkfield might solve the mystery of earthquake prediction for good.

But instead it was back to the drawing board for science.

Holy shit!

Holy shit.

Oh, my God.

Holy cow.

And as every year goes past, more earthquakes continue to plague our planet.

-Out here, out here!

-What happened to the telescope?

-Destroyed.

Go, go, go, come on!

It may fall.

I got it on tape!

Holy shit.

I got it on tape.

Go, come on.

In the last decade alone, tens of thousands have died

in Turkey, India, Iran and Pakistan.

And it was an earthquake that caused the Boxing Day Tsunami,

killing a quarter of a million people in 2004.

Then in May 2008, it happened again.

This time in Sichuan Province, China.

Six months after the disaster, geologist Mike Ellis

is travelling to China to investigate the earthquake.

Mike has worked in this region before

so he always knew there could be a major quake here one day,

but he didn't think he'd ever get to see it in his lifetime.

I've chased quite a few earthquakes, as we call it, um, Taiwan downwards.

Big earthquakes like this happen in the ocean all the time but of course you can't go there to see them

so academically and scientifically it's a treat

to come to an earthquake like this

but of course it's a very sobering experience as well.

For the inhabitants of Sichuan Province, Monday May 12th was a day like any other.

Many people were at work, their children in school,

while others were simply out enjoying the sunshine.

Little did they know that the ground beneath their feet

was about to be ripped apart by a rupture that would travel

100km in just 50 seconds.

REPORTER: A massive rescue operation is underway after a powerful..

..thousands are killed after a massive earthquake hit South West China.

At magnitude 7.9,

it was one of the world's most powerful earthquakes in decades.

But even after the shaking had stopped, the real drama was only just beginning.

As entire towns collapsed, thousands of people

were crushed to death or killed by falling masonry.

And strong aftershocks, some higher than magnitude six,

continued to strike across the region causing new casualties and damage.

REPORTER: The rescue operation is one of the biggest ever.

50,000 troops have been mobilised....

..mourning for victims of the Sichuan earthquake.

Rescue work continues but very few victims are being found alive.

Months on, and Sichuan still lies in ruins,

but Mike hopes to find answers among the broken houses and upturned soil.

He'll be travelling with Jing Liu,

a Chinese earthquake geologist who's been mapping the rupture since May.

The county town of Beichuan is 138km from the earthquake's epicentre,

but it lies in one of the worst-affected areas.

12,000 people died here,

three quarters of the population.

Coming back for the first time since the earthquake,

Mike is struck by what's happened to the place he once knew well.

It's very sobering.

Um, not something that you want to see, really.

On the river, there were some trees and a cafe down there, I used to sit and play Mahjong.

Now it's completely chock full of sediment and, er...

Mike came here before to map some of the earthquake faults in this area.

This is one place where I think the rupture did coincide quite well with the fault, the mapped fault.

We mapped along there and then through the valley and up over there.

By mapping faults, Mike hopes to predict where and even when an earthquake may strike again.

Now he has his best opportunity in years.

The recent earthquake has revealed faults never seen before.

Even though Mike is hundreds of kilometres from the tectonic plate boundary

between India and Asia, this is major earthquake country.

Geological maps of the region suggest that there are thousands of faults

hidden in the mountain range that fringes Sichuan Province -

the Longmen Shan.

So here you can see the big picture

of the India, Asia collision region I suppose you could call it.

White area for a high elevation and the darker areas are lower.

So here is the Himalayan arc,

India of course, moving up into, into Eurasia,

and that's occurring about 40, 45mm per year,

which is pretty fast in plate tectonic terms.

There's a series of thrust faults

that come down and around the Himalayas.

This is the the plate boundary

and so there's Longmen Shan

and it's facing the very flat and relatively low Sichuan basin.

It actually is, geologically this is a wonderful enigma.

It's always exciting to find a place that has not been explained yet.

I think we're all looking for something that we can make an impact with.

Over in California, most of the mapping work has already been done.

Here, scientists are all too aware of the cost of not knowing where the faults are.

Their wake-up call came in 1906, when a magnitude 7.9 earthquake

bought San Francisco to its knees.

The violent shaking and fires afterwards killed thousands

and destroyed much of the city.

Ever since, the state has learned to live with the threat

that another major earthquake could strike at any time.

Over 100 years later, California is now the place to be

for seismologists and geologists the world over.

There are not a whole lot of earthquakes in London, you know,

and the ones that happen are piddly and not worth studying.

So in in my game where we measure things, you'd really like...

something bigger than a seven.

Eight's nice, nine is terrific.

Not so good for people, but terrific for the scientists.

Roger Bilham was born in England but moved to America to be nearer

to faults like the San Andreas, cause of the 1906 earthquake.

So here look, have a look at this, this beautiful flat valley here

with a hill on each side. The fault runs right down the middle

and this slipped in 1906.

It slipped only about two metres here,

as we get further north it slips increasingly more

until you get north of San Francisco

where it becomes about six metres of slip in 1906.

By mapping out California's faults,

scientists are beginning to understand how tiny slips in one place

could lead to huge earthquakes somewhere else.

Roger hopes to pick up a small sign

that might predict a future disaster.

He travels from fault to fault

checking on a collection of home-made instruments

that he's buried at sites up and down the state.

Well, I I consider them my babies.

You plant them in the ground and then they they live out their rather dull but informative existence

sending us information about the movement of these wonderful faults.

So yes, I quite enjoy it, except when it rains, and it doesn't do that much.

Ah, and sometimes the local people shoot at you, which isn't such fun.

-Sorry?

-Well, yeah. I work all over the world,

but California is the only place where they really, really tried to shoot me,

and, er, that's the sort of macho people that go around California with guns.

They sit on these interesting faults and they don't want you to measure them.

Astonishing.

We're not going to get shot at by the owners here, are we?

-No, not at all.

-Sure?

Yes, absolutely, they're lovely people.

OK, so if you can squint along this fence you will see it's offset.

Now this fence was put in after the 1906 earthquake,

so the offset has occurred since 1906.

And we know from measurements along the road

and from the creek meter in the the field

that it's moving at about a quarter of an inch a year, relentlessly,

and when the San Andreas Fault slips,

this side of the road is going off to the South, this side of the road is going off to the North,

so this is stuck next, this is glued to the Pacific plate

and you're standing on the North American plate

going away whizzing past me down sort of Mexico direction.

Let's go and visit the machine.

So this is the important step -

check the bulls are in the right place.

So it's just over here in the grass.

I sometimes worry there's a snake under here.

Not this time.

There is an element of, er, a Heath Robinson contraption about it.

It's a very simple gadget, it's a cylinder with, um, a rod,

the rod is connected across from the other side of the fault.

When the fault slips it pulls this rod away from the metal sensor.

It has a range of about, er...

This one is about 30mm and so because there's 7mm of slip here,

about every four years I have to reset it.

But first, download the data.

I'll get my computer out.

7mm of slip might not sound like much

but it could have a devastating effect.

150km up the fault in San Francisco the tectonic plates are locked,

and eventually this pent-up energy

will be released in the form of an earthquake.

Every time that Roger's machine measures the fault slipping,

known as a creep event, this may help to calculate

the amount of stress that's building up beneath the city.

Oh, we've got a creep event! How exciting.

The black line here is, er, can you see that OK?

So the black line is the temperature decrease

from mid-summer to... It's upside down, OK,

we could actually turn it up the other way but let's do it like that,

so there's the temperature decreasing as a function of time

and here is, er, a creep event

where the fault suddenly starts slipping at a few millimetres per second

and then over the next day or two, in fact continuing for several weeks.

Even if you'd been standing on the fault, you wouldn't have noticed it

cos it's really a very slow, quiet process.

So until people have put instruments like this on the ground,

we had no idea that these things were occurring.

Science has mapped every fault in California,

but in China, the process is only just beginning.

Xiao Yu Dong is 42km from the earthquake's epicentre.

What was once flat farmland

was completely transformed on May 12th.

To find the fault here, Mike's looking for earthquake scarps -

steps in the landscape where the rupture has lifted the ground up.

This level I'm standing on right now used to be up there.

That's a good two to two and a half, possibly even three metres.

So that entire free surface is the earthquake scarp.

And no doubt that will quickly be bricked up

and you won't be able to distinguish it so easily.

This is also a superb place, by the way, for finding,

um, unambiguous lateral offset, if there is any.

You can see where I'm standing, there's a nice straight wall,

and I can see from here that the offset,

the natural offset here is about about a metre,

maybe a little bit less than a metre to this wall,

so essentially this wall here was that one back there.

Before the rupture actually happened,

probably at this location there was a lot of shaking and rolling

and then this this side of the village just rose up like this.

It takes about between 10, 15, 20, maybe even more seconds to do that.

That's actually quite slow when you're standing here as an eyewitness

and seeing this thing just rise up like this

out of the ground and then this entire part of the village

is now a metre to two metres higher.

It's hard to imagine what this place once looked like,

but one villager has kept a memento.

-TRANSLATION:

-I really liked the beautiful view we had of the landscape here,

so I took this photograph from the first floor of our house.

Before the earthquake the road used to be completely level.

The ground too, everywhere was level,

but now it's dropped by one or two metres.

The ground just slid down, it was amazing.

For the people of Xiao Yu Dong, May 2008 was the first time

any of them had ever experienced a major earthquake.

But Mike is beginning to suspect

that there have been other quakes here in the past.

The two things that important here is that the elevation difference between where I'm standing right here

and up there is significantly higher than it was

further along the the rupture

and further back along the rupture that way we saw the modern earthquake scarp

being very irregular and this looks almost identical to that,

so this is very suggestive.

So I would, I would love to be able to walk,

if I could just walk up here a long way.

To Mike's expert eye, every rise and dip in the landscape

could be evidence of a whole history of earthquakes.

So right here I'm standing on an old scarp that's very gentle now.

And it continues to be this sort of hammocky topography

in these fields, so this sort of old scarp

and the much greater relief here at this point

would tell us that this has been the place of an earthquake before

and probably several before that too,

so points to the importance of mapping these things in great detail.

But mapping out faults isn't always so straightforward.

Mike and Jing have come to a valley further along the rupture

where the ground rose up twice as high as in Xiao Yu Dong.

They're hoping that a scarp this size will tell them

more about earthquakes that have happened here in the past

and those that are yet to come.

But recent heavy storms have transformed the landscape.

-TRANSLATION:

-Hello, was there an earthquake scarp here before?

-TRANSLATION:

-Yes, but it was washed away - our village was too.

Tons of earth fell down, part of the mountain just collapsed.

It's probably there,

but not where the river has incised through it

but if you follow it up a little bit there must be some remnants...

Maybe, maybe.

I would hope so. A six-metre scarp can't disappear completely.

That is the scarp.

Let's see, you can go up and I'll find this place for the grass.

Before this September the ground was like at this level

and this level used to be lined up over where, um, Mike is standing.

So I'm standing here on a surface that now is occupied by Jing down below there.

The ground on my left was pushed up six metres

and moved to the right by six metres as well,

so the mountains as a whole are shortening,

the crust is shortening and moving sideways

and that sideways motion is small,

but it is an expression of India colliding into Asia.

This landscape we're in now has been formed by many, many earthquakes,

hundreds and thousands of earthquakes.

Despite the damage from the storms, Mike is beginning to understand

the history of earthquakes in this particular valley.

But this evidence is fast disappearing.

Obviously, over time, the subtle signals for any specific earthquake

disappears very quickly, and this has virtually disappeared

in less than six months, so as we're scrabbling around the hillsides,

we see signals every now and then, but the data is very sparse, very difficult to put together.

Geologists like Mike hope that by mapping the past,

they'll come closer to predicting the future.

But even if you know where to measure,

every earthquake is complicated by a significant factor,

how big it's going to be.

We don't know what makes an earthquake start today instead of yesterday.

We also don't know what makes it stop

and that's what controls the size of the earthquake.

A magnitude three starts at a point,

you start to slip at a point and you have a rupture front that

travels out and causes more of the fault to slip,

and in a magnitude three, you travel out this far.

In a magnitude five, it travels out for a kilometre or two.

In a magnitude eight, it travels out for 500 kilometres,

so when we're trying to predict what the earthquake will be, we're saying, it starts here,

but does it stop after one kilometre, or does it stop after, um, 100 kilometres?

Predicting the size of an earthquake is essential.

Millions of quakes happen all over the world each year,

but the vast majority are too weak even to be felt.

The real challenge for science is to work out when one of these

little earthquakes is going to develop into a major disaster.

You don't want me to predict every earthquake, there's going to be 50 in California today.

You want me to predict which of the 35,000 we record each year

is the one or two large enough to do some damage, and really, what we want to do

is really predict just the one that happens every five or ten years that does a lot of damage.

'Live, Los Angeles tonight, battered and bracing for the worst.'

The last earthquake to do a lot of damage in California

stuck in Northridge, a suburb of Los Angles, in January 1994.

Measuring magnitude 6.7, it killed 72 people and caused over

20 billion in damage, making it one of the costliest natural disasters in US history.

'The earth is literally split here.'

'The city wakes up to a nightmare.'

But one man saw it coming.

Professor Vladimir Keilis-Borok, an 87-year-old

Russian geophysicist at the University of Los Angeles

has developed a way of predicting earthquakes, with a surprisingly high level of accuracy.

Out of 17 earthquakes worldwide

which happened since '92,

we have predicted 12.

'The Earth's fury

'unleashes fire, and flood, and fear.'

The prediction method doesn't come from the world of geology, but from an extraordinary branch of maths...

chaos theory.

Chaos theory seeks to find an underlying order in some of nature's most random processes.

Weather systems,

the way birds flock together, or even the distribution of leaves on a tree.

There didn't seem to be any order to earthquakes, but Keilis-Borok

brought together scientists from multiple disciplines

to study the problem, including seismologist David Jackson.

Well, the general theory is that when the earth is in a chaotic state,

there will be some features that can be recognised.

And typically, those features are in the smaller earthquakes that occur, and how much a small earthquake

brings with it, some immediate follow-on earthquake.

Looking at some of California's major earthquakes in the past,

the UCLA team thought that they could see patterns in the smaller quakes that preceded them.

Today, they look for similar patterns, chains of small

earthquakes linked by their size and the time they strike.

If they think they see a new chain that matches their historical data,

the group then issues an earthquake alarm.

Sometimes, humans can see the patterns and we propose

something that seems to us logical in terms of the way earthquakes behave, but sometimes, their patterns are

too complicated and the hope is that computers, using vast amounts of data,

and, er, combing the data for those patterns, can out-think us in that particular way.

But the patterns haven't always led to accurate predictions.

Nine years after Northridge, Keilis-Borok's team announced that a major earthquake

would strike near Palm Springs by September 5th, 2004.

Once again, the enigmatic Russian was putting his career on the line.

But this time, nothing happened.

The team's work continues to be a mixture of success and failure,

but Keilis-Borok is confident that he can improve his hit rate.

There is no such thing as

100% accuracy, but...

we believe the accuracy can be increased by factor at least five.

It remains to be seen if chaos theory and maths are the answer to earthquake prediction.

In the meantime, science has been forced to explore other,

sometimes stranger avenues, to try and solve this problem.

Since time began, people have been reporting weird goings on

in the days, or hours, before an earthquake. Sudden upsurges in migraines...

..mysterious changes in ground water levels,

but perhaps the most bizarre phenomenon involves animals.

Guangxi province, South West China.

This farms lies at the centre of an intriguing experiment to predict earthquakes...

..using snakes.

TRANSLATION: We call this snake Dragon,

or Earth Dragon, here in China.

In Chinese culture, we think of ourselves as children of the dragon,

so there is no need to be afraid of snakes.

Jiang Weisong, head of the local earthquake bureau, has a team

monitoring these snakes 24 hours a day using webcams.

It's thought that snakes may be able to sense earthquakes in the same way

that they locate their prey.

Using their inner ears to pick up vibrations in the ground.

If a small earthquake happens within 120 kilometres of this region,

for example, a magnitude five,

then the snakes will come out of their holes

and crawl along the walls, trying to escape.

If a major earthquake happens nearer, then the snakes would

smash themselves against the wall continuously,

until they killed themselves.

It has a very powerful effect on them.

We'd like to see this happen three to five days in advance,

then we'd have time to analyse it and make an accurate prediction.

Animal predictions aren't without foundation in China.

They've been attributed to saving tens of thousands of lives.

At the height of the cultural revolution, the city of Haicheng was

evacuated after many people reported seeing animals behaving strangely.

When a magnitude seven earthquake struck days later, Haicheng was heralded as the first time

one of these disasters had been predicted using animals.

But since then, no-one has ever been able to replicate the results.

As far as I know, I'm the only person doing research in this area.

Even in China.

I can understand why other scientists might not recognise my work, but I think the reason they distrust it

is that they haven't done the practical experiments themselves.

If we can have more observation stations, then our predictions would be more scientific and more accurate.

One flower doesn't make a spring, but hundreds of flowers can definitely make spring.

In the hours, or days, before an earthquake, it's not just animals that can be affected.

There's another even stranger phenomenon that can be used for prediction.

Bright lights that appear in the sky.

This photograph was taken in September 1966,

before an earthquake struck the town of Matsushiro, in Japan.

Many other people have reported seeing these lights,

but no-one has ever been able to prove why they might happen.

Today, however, NASA physicist Friedemann Freund believes he may have found the answer.

Gary, will you tell us when you make contact?

Now, it starts.

In 2005, Freund made a peculiar discovery that if you crush a rock

to almost breaking point, it produces a tiny electrical current.

Now, we are already driving

something like four nanoamps

through this rock,

the pressure increases more and more,

the current increases,

now the pressure has already reached its maximum value and the current

will stay up there, and as long as the load stays on the rock,

the current will continue to flow,

and that is the simulation for what we believe to be happening

in the Earth prior to an earthquake, before they rupture. If you can imagine

that you have a cubic kilometre of rock being stressed or...the currents translate

into thousands, ten thousand, sometimes hundreds of thousands of amperes

that could flow out of a cubic kilometre of rock.

The currents going through the rock can give rise to other oddities, including one that Freund believes

may explain the lights in the sky before an earthquake.

If it were dark here, we would start seeing little flashes of light forming along the edges

of these rocks. Maybe in nature,

they are sufficiently strong that they couldn't become luminous

phenomenon known as earthquake lights that can happen before

earthquakes, during earthquakes and also during the aftershock series.

You think there's a connection between this and...?

Oh, yes, yes, there's definitely a connection.

Friedemann Freund is fighting a tide of opposition from mainstream science,

but he's convinced that he's right and he's prepared to put his money where his mouth is.

So far, everything that I've shown you was essentially done on a shoe-string budget,

with lots of private money going in there

and very, very little funding from any government sources.

Who's been funding it up until now?

Well, I eventually paid most of it out of pocket, we are still

having a very, very minimal funding level.

-Just out of your own wallet?

-Yes, I've spent close to a million dollars

on funding this research, because nobody believed me.

That's a hell of a lot of money just to try and...

Well, because I know that I'm on the right track, so I will pursue this

and bring it to the end. Now, people start to listen, and yes, now they are convinced.

With something like this,

as clear as you can hope you would get it.

The scientific community may still be sceptical about Friedemann Freund's rock experiments,

but his research is now being used in a commercial application...

QuakeFinder - a device that measures electromagnetic changes

in the ground to sense if an earthquake is coming.

It's, er, basically, a computer system, er, set of electronics

to process the data, a simple hard drive from a laptop to record it,

a radio link to bring it into, er, a farmer's house maybe 200, or 300 feet away, and then we have

a satellite dish that takes the data

and brings it through a satellite link up to our site here in Palo Alto.

It's still early days for QuakeFinder, but it may have already had a minor breakthrough.

In October 2007, the little white boxes picked up electromagnetic

signals shortly before an earthquake struck Alum Rock.

A small community south of San Francisco.

This is the, er, the actual data from the, er, Alum Rock earthquake,

if you're interested in that, these are the days prior to the earthquake

so the, er, magnetic pulsations that we see are very, very few and far between, this large one here

is a calibration signal that we generated ourselves just to make sure everything was working OK.

About two weeks before the earthquake, we started to get these

very large pulsations, the next few days, it got busier and busier

it spread out over more of the day

until finally, right there, the earthquake hit.

But was there a moment, Tom, when this data was, you know,

more and more data's coming in from Alum Rock, were you thinking, "Crikey, this must be an earthquake?"

I'll be honest with you, no.

Because we're still trying to discover what the pattern is,

we're not quite sure how many days it should be there.

This was, we didn't know if it was a large earthquake or a small earthquake, all we knew was that

it was only happening at that one station, not at any of the other stations.

It's going to take a great deal of research and a lot more earthquakes

before theories about rocks or animals are ever proven.

But mainstream science has practically given up on funding these kinds of experiments,

and many geologists even question the value of prediction.

Well, what would you do with it? Let's imagine I can tell you

there'll be an earthquake in a hour, what would you do?

You'd get your camera out, or your tape recorder or something,

if you were in a building, you'd probably go outside because you

might think it's gonna fall down, that's not particularly useful,

the building is gonna fall down, that is the problem.

Would you rather have an hour to get out of a building or a building that didn't fall down in the first place?

It's a real possibility that we'd have more people dying on the freeway trying to get away when we made

a prediction than we would have killed in the earthquake when it happened.

Unable to predict these disasters, California has turned itself into

one of the most earthquake-proof places on the planet.

In Los Angeles, every new skyscraper has been built following strict construction codes.

Hundreds of freeway flyovers have been retro-fitted and re-enforced, and as the city expands

into the surrounding counties, the fault lines are what matters when it comes to choosing real estate.

Would you live directly on it, Ken?

No, when we were looking for a house, we looked at some houses that were right on top of

the Sierra Madre fault and we decided to keep looking.

Similarly, when we were looking at the house, I was probably

more interested in the structural integrity of it and the construction of it than most people would be.

Geologist Ken Hudnut works for the US GS, preparing Los Angeles for the next big earthquake.

You can see here a brand new development going right up to the Cucamonga Falls.

We think that that fault is capable of a magnitude 7.5,

7.6 earthquake on its own,

without any involvement of the San Andreas Fault itself.

That gap is there because they have to set back away from the fault,

that's the case for any fault that's considered active,

and by that, the state law says if it has had

surface faulting within the last 10,000 years, you need to set back from it.

Over in China, the devastation in Sichuan Province serves as a stark reminder

of the potential cost of building on earthquake faults.

Mike and Jing have come to Bailu,

a mountain town around 50 kilometres from the earthquake's epicentre.

The fault passes right through this valley, heading straight for the town's middle school.

Well, this is quite something.

Thanks to an astonishing stroke of luck,

the rupture missed both of the buildings containing classrooms,

but at the end of the playground,

the earthquake demolished a block of housing, killing several teachers.

What we would, er, be very happy about seeing here,

um, extraordinarily happy, is that these buildings that are built either side of the rupture didn't collapse,

and that one over there appears to have very little damage, you know, apart from broken windows,

but, er, this rupture goes through

what used to be the dormitory for the school teachers and that's completely gone.

Um, so first lesson, don't build across a rupture.

The school has now become a tourist attraction,

but Mike and Jing can see clues in the landscape that suggest this disaster could have been avoided.

The fact that beyond the school buildings, the land is higher

and it may be there was an old scarp here.

In the topography, you can see the long-term effect of this fault

slicing straight up that valley and giving that notch.

To be fair to the authorities, there are many fault scarps in these mountains

and they're very, very difficult to find, we had only just begun to find some of them,

it takes a long and sustained effort.

It took people in California decades to map out the fault scarps in any sort of precision.

There were fifteen million people displaced by the earthquake. The Chinese authorities

don't have time to wait until they've mapped the precise location of Sichuan's faults.

TRANSLATION: If someone shouts "earthquake," put your hands on your heads.

Hands on your heads and hide under the desk.

The best that many schools can do now

is simply rehearse for the moment an earthquake strikes again.

Elsewhere in Sichuan, they're rebuilding at a rapid rate.

But the vast majority of these new homes won't be strong enough to survive another major earthquake.

For Roger Bilham, this is a problem that's endemic throughout the developing world.

I can go here here, here OK, where my fingers stab the map,

there will be a magnitude seven earthquake within,

you know, a few inches of it in the next 30 years maybe in the next year.

I've made a forecast that it's possible right now

for one million people to be killed by a single earthquake, OK?

Now, that's a terrible thing to say and it's a thing that has

no precedent, it's never happened in the past,

why can I make such a crazy statement?

Because there are now cities of eight and ten and twelve million people along this earthquake belt

that have never been there in the past and that knowledge is sufficient, surely,

to drive those countries, if they're responsible to mandate earthquake resistance.

And it only costs about another 10% more.

What it means is...

buying fewer guns and better concrete instead.

Modern seismology has been with us for over 100 years,

but scientists are still no closer to predicting earthquakes.

However, they haven't completely given up.

But where they once thought it might be possible to predict months in advance,

now, it's come down to a matter of seconds.

We are prototyping earthquake early warning, this is also sometimes called now casting,

because it's not saying there's going to be earthquake, its rather saying an earthquake has already begun

and we're giving you that information before the waves have travelled from the fault to where you are.

The warning system will start from stations like this, located along the San Andreas Fault.

Instruments buried deep underground will track

how much the fault is moving, using high-precision GPS satellites.

The, er, antenna itself is inside of this hemispherical shell and it's

constantly locked onto the radio signals from the GPS satellites.

Each leg of this tripod goes down about 30 feet,

ten metres into the ground and firmly attached to the bedrock here.

But to have this system up and running, these instruments need

to be able to feed back data the moment the ground starts to shake.

In a big San Andreas earthquake, this station would move more than a metre

within a matter of less than ten seconds, so other stations like this positioned all along

the San Andreas Fault could actually track the rupture as it's progressing.

We're seeing it here coming up the fault

and the red is where there's a lot of damage, so we could have

used our stations in this area, at this point, 20 seconds into the earthquake.

Know that it's underway, we've got a big earthquake started and send

that information to Los Angeles that the earthquake's underway.

We could potentially get up to a minute's warning.

You could hook this up to your elevator and have your elevator moved to the nearest floor and open

the doors, so people weren't trapped for the next few days after the power goes out.

We could ring an alarm in operating room, so the surgeon pulls the scalpel out of your chest.

You could ring an alarm where they're handling toxic materials, so you're not pouring out chlorine.

You could shut down critical computer facilities, we could also be stopping any rail lines, we could be flashing

the messages up on freeways, you know, "earthquake coming, slow down."

Earthquake prediction doesn't come any more high-tech than this, and now casting

is not only possible, it's surprisingly affordable.

Well, I think the public expects us to be able to predict earthquakes, and of course, we really can't.

But this is something that we can do, we have the technology, we've tested it, we've developed systems

that work and we know that we could build an early-warning system, at this point in time, we don't have

nearly the instrumentation in place to be able to do that kind of earthquake early warning,

some estimates, we think it could cost about 100 million in all.

And the price tag we're looking at for a big earthquake on the San Andreas is, er, 200 billion

and up, so a 100 million system to help reduce the damages seems like a good investment.

This kind of early-warning system might work for California one day,

but for most places in the world, science's best answer to the threat of earthquakes

is to construct better buildings and map all the faults in potential disaster zones.

It's really important to know where these active faults are exactly,

so that at least if you can't predict the earthquakes,

then we know where not to build.

But not everyone thinks that prediction is totally dead,

there's still a sneaking hope that someone, someday, may find the Holy Grail of seismology.

Some seismologists would say, "No, it's impossible and I'm not willing to go that far,

"because we don't understand

"why exactly earthquakes happen, so if we don't understand that, we can't say they're not predictable."

It's an interesting challenge, we might get closer to it, there are obviously certain things

we're going to learn and have learnt, maybe one day,

we'll get lucky and find that we've been looking at the wrong thing,

but right now, whatever we do has resulted in, well, I have to say failure, but you know,

we're trying, we're doing our bit, we think we'll get there one day.

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