Original subtitles

Deadly...

highly destructive, and impossible to predict.

Earthquakes are one of Mother Nature’s

most terrifying forces.

Every year, there are half a million

detectable earthquakes.

Only 100,000 of those are strong enough to be felt.

But 100 of them are so powerful

that they cause damage, injury and even death.

The world’s surface is not solid.

It’s made up of separate tectonic plates

that are constantly moving and shifting.

Sometimes the edges get caught against each other,

storing up huge amounts of energy.

When that energy is released, the forces can cause chasms

to open in the ground and buildings to collapse.

With eyewitness accounts

and fascinating expert insights,

we investigate a catastrophic magnitude 7 earthquake

that struck Haiti on the 12th of January 2010,

as well as two earthquakes that occurred in Mexico City

exactly 32 years apart,

and see how lessons learned from the 10,000 deaths

in the first disaster helped to save lives in the second.

First, in this episode of Deadly Disasters,

we’ll focus on the horrific earthquake

that struck Haiti in 2010.

Located on the West Indian island of Hispaniola,

Haiti is one of the poorest nations in the world.

More than half its citizens survive on less than $2 a day.

It has a population of nearly 10 million,

many living in makeshift dwellings.

Non-profit organizations like ECO Works

have been helping Haitian communities foster

infrastructure development since 2008.

The infrastructure was what it is,

unfortunately, still today,

which is that for people who live in poverty,

which is the greater majority of the population,

they don’t have access to power, to water or to sewage.

The country is no stranger to natural disasters.

In 2008, it was hit by four hurricanes

which caused flooding, landslides,

and left 800 people dead.

This impoverished country was still struggling

to recover from those hurricanes when they were struck

by one of the world’s worst natural disasters.

Just before 5:00 in the evening,

on the 12th of January, 2010,

Haiti was suddenly rocked by a magnitude 7 earthquake.

It was the most powerful earthquake

to hit the area in more than 200 years.

Basically, earthquakes are the result

of the movement of the earth’s plates.

The plates move because of the internal heat of the earth

which moves them around.

And the plate boundaries,

where the plates meet each other,

that’s where you can generate earthquakes

because you got giant fractures in the earth’s crust,

and those are moving very slowly...

They’re moving at about the same rate as your fingernails grow,

which is from millimeters to centimeters per year.

But eventually, the stress is so high

that it overcomes the friction

and then the fault moves very rapidly,

a couple of meters per second, and that would then

generate the earthquakes, which travel as waves

through the solid part of the earth.

The epicenter of this cataclysmic event

was below the city of Léogâne,

about 25 kilometers from the capital, Port-au-Prince.

The earthquake was unusually near the surface,

occurring at a depth of only 13 kilometers.

This dramatically increased

the level of shaking above.

Port-au-Prince in Haiti is very close to a plate boundary

called a Gonâve Microplate and that southern boundary

stretches all the way from Jamaica.

In fact, it goes all the way through the center of Jamaica

and then goes all along

the southern peninsula of Haiti

and passes very close to Port-au-Prince.

Shocks quickly spread throughout Haiti

and the neighboring Dominican Republic, as well as

to parts of the nearby Caribbean islands of Cuba,

Jamaica and Puerto Rico.

Roughly three million people were affected

by intense shaking that was strong enough

to cause damage to buildings.

The closer they were to the epicenter,

the more destruction occurred around them.

The capital, Port-au-Prince, and the densely populated

surrounding areas didn’t stand a chance.

The same amount of energy as 35 atomic bombs,

like the one that destroyed the city of Hiroshima,

was released in 30 seconds of intense shaking.

Port-au-Prince was simply ripped apart.

What shocked me the most is the magnitude

and the horror of the devastation.

It was just unimaginable.

It looked like a war zone.

People were crying, people were looking

for loved ones under the rubble,

sometimes with their bare hands, trying to get them out.

It was really extremely painful and hard to live through.

You cannot find no person alive down this house.

No life.

The Haiti earthquake was a magnitude 7,

which classed it as a major earthquake.

But how exactly are earthquakes measured?

Earthquakes are measured either by the energy they release

or by the damage they are doing.

The energy that is released is measured with instruments

that we call seismographs, and they measure the amount

of energy that it released.

There’s a certain distance, graphically,

that you can see the different waves that travel.

And from the distance and the amount of energy released,

we can determine the magnitude of the earthquake.

Previously, we used what was called the Richter scale.

And that’s the most famous everywhere around the world.

They still talk about the Richter scale.

And so, actually, the modern magnitude,

what we call the "Moment Magnitude",

is actually based on the Richter scale.

The reason they did this was because

people already knew what the Richter scale was,

and so, if you have an idea of--

Okay, there’s a magnitude 5.

Okay, so we have a moment magnitude,

we put it very similarly

to magnitude 5 from the Richter scale.

So then it looks the same. And people know what it is.

The damage from this magnitude 7 earthquake

was particularly devastating in Haiti.

One of the problems in the 2010 Haiti earthquake

was the quality of the construction was very poor.

Much of the construction was informal,

there were no inspections of the buildings

and there was also the use of cement-sand mixtures,

they were trying to stretch the cement

so they mixed it with either too much sand

or sometimes sand that had salt in it,

so that the cement was not very strong.

When the earthquake struck,

thousands of buildings collapsed,

killing or trapping their occupants inside.

While such a powerful earthquake

could be expected to cause destruction,

experts were shocked

by the catastrophic failure of so many buildings.

Even new and renovated schools, police stations...

bank branches, high-end hotels, and hospitals.

Some seismologists sort of have a saying

that "It’s not earthquakes that kill people,

it’s buildings that kill people."

The cathedral and the national palace

were in ruins.

The national prison in Port-au-Prince

was so badly damaged

that 3000 dangerous criminals were able to escape.

The damage happens when you are within buildings

that are not built according to code

or fortified for earthquakes,

so the infrastructure that is not well prepared

for an earthquake is more dangerous

than the earthquake itself.

In 1989,

a comparable earthquake

occurred in San Francisco,

but resulted in the loss of only a single life.

The difference in that instance was infrastructure.

Haiti simply lacked the same building standards,

resulting in more widespread devastation.

These were two similar earthquakes

with hugely disproportionate consequences.

In the town of Léogâne,

right above where the earthquake occurred,

90 percent of the buildings had simply ceased to exist.

While in the small coastal fishing port of Petit Paradis

on the west coast of Haiti, a tsunami wave swept inland,

dragging several people to their deaths.

Haiti was still trying to recover from the effect

of the hurricanes two years earlier.

In the face of this latest catastrophe,

the country was unable to cope.

Vital services needed to relieve the stricken country

were either damaged or destroyed.

What is the definition of a disaster

for professionals like myself?

It is an event that is of such magnitude

that the local or the national government

cannot face it alone.

Efforts to get food,

medical aid and water to the survivors

were hindered by the breakdown in communication systems.

Add to this, the fact that in the same year

the earthquake happens in January, in October,

there is a cholera epidemic, that was brought in

by a contingent of the United Nations.

Now 800,000 people are sick,

and more than 10,000 die.

So when you talk about the logistics and the magnitude

of what we were dealing with, it was beyond imagination.

Although the runways at the Toussaint Louverture

International Airport were intact,

damage to the control tower

meant that planes couldn’t take off

or land safely.

At the main seaport, piers had collapsed

and cranes had been knocked over, so ships were not able

to unload urgently needed supplies.

Almost all paved roads were blocked,

due to severe surface damage,

fallen trees and debris from collapsed buildings.

In the hours following the quake,

survivors dug through rubble, often with their bare hands,

to rescue family and friends.

Dusk fell just two hours after the earthquake.

In the eerie darkness,

rescuers had to use flashlights

as they continued to claw at the rubble,

trying to reach those trapped beneath.

Everywhere is dark, she’s just like an incredible bright star

in the middle of this darkness and it’s a wonderful feeling.

That night, many people in Haiti

were forced to sleep on the streets,

either because their homes had been destroyed

or because they were terrified of aftershocks.

When a fault moves and causes an earthquake,

it changes the distribution of the stresses around the fault,

so aftershocks are generated.

They’re usually smaller than the main shock

but there have been cases where

they’re almost as large as the main shock.

As daylight broke on the morning

following the earthquake,

it became clear that thousands were either injured

or had lost their lives.

Most of the wounded had nowhere to go.

Medical centers had either been destroyed

or were out of action.

A lucky few were treated at the only hospital

operating in Port-au-Prince, a mobile field hospital.

By chance, the hospital had already been set up

by the Argentine Air Force,

who were part of a U.N. peacekeeping mission

stationed there.

During the first night after the earthquake,

staff managed to treat 1000 wounded survivors.

Helicopters airlifted those most gravely injured

to Santa Domingo in the Dominican Republic.

Doctors and nurses who had survived the earthquake

set up makeshift triage centers

in parking lots and other open spaces.

Medics attended to the worst

of the injuries as best they could.

As the sun beat down on the car park

of the Hospital de la Paix, those waiting to be treated

lay among those who were already dead,

while others, with wounds open to infection,

could only sit at the roadside,

hoping that help would arrive.

Later, China announced that

a 50-member rescue team would be sent to Haiti.

But as the hours passed,

the horrific scale of the devastation

was becoming all too clear.

The Haitian president, Rene Prevail,

told reporters that he believed over 100,000

may have perished in the earthquake.

Many of the dead were hastily buried in mass graves.

The presidential palace

and many other government buildings

had been smashed, hampering the country’s

already unsteady central government.

Those who survived and who were civil servants,

they also suffered tragedy, so given this situation,

which was so painful and so beyond imagination,

I actually give very high points to the government

because they did regroup quite quickly

and they tried to coordinate as much as they could.

Haiti was a country that had ceased to function.

This terrible disaster

was turning into a horrific nightmare.

Thankfully, towards the end of the day

after the initial earthquake,

the first international aid agencies began to arrive.

Commandos of U.S. Air Force Special Operations

managed to land at the airport in Port-au-Prince.

Due to the damaged control tower,

no aid flights had been able

to bring relief to the survivors.

Haitian authorities handed the airport

over to the U.S. officials, who were able

to allow aid flights to land the following day.

The U.S. army did very well,

and so that helped a lot

on the distribution of the aid that came--

food, water and everything else.

A week after the earthquake,

some aid had reached the capital

but in the rest of the country,

people were still fending for themselves.

Even before the disaster,

only half of Haitians had access to clean water.

Now that supply had been cut off.

People searched the streets

carrying empty plastic bottles,

gathering water from broken pipes and gutters...

wherever they could find it.

With food running out,

some thirsty and desperately hungry people

began to forage for supplies among the ruins.

The United Nations, who were at the forefront

of the initial response,

already had a presence in Haiti.

But they had suffered many casualties as well.

Their headquarters had collapsed,

and about 150 U.N. personnel,

including the head of the peacekeeping mission,

were unaccounted for.

The initial response led

by the new acting head, Edmond Mulet,

was criticized for being too focused on security.

They were concerned about the 3000 inmates

who had escaped from the collapsed jail

in Port-au-Prince.

The UN wanted to find

the escaped criminals

and maintain public order.

Struggling Haitian police regrouped and attempted

to deal with the increasingly chaotic environment.

Several days after the initial earthquake,

exhausted rescue teams continued to comb

through the rubble, desperately searching

to find anyone left alive.

Although some people had been miraculously rescued,

hope of finding any more survivors

was rapidly fading.

Despite more and more aid

finally arriving to the country,

it was not enough to deal

with the ever more desperate situation.

Emergency medical teams were working

out of shipping containers,

performing lifesaving amputations,

and urgent calls went out

to U.S. medical schools for extra volunteers.

If you have teams that are prepared to get people

to safe places, to treat people who are injured

or damaged in some medical way...

you’re gonna reduce the death toll enormously.

Preparation is the key to reducing

the negative effects of any natural catastrophe.

As aftershocks rocked an area

15 kilometers west of the capital,

aid officials feared that if help could not be delivered

to the three million survivors

still fending for themselves,

there would be a total collapse of law and order.

U.S. Marines on troopships began disembarking in Haiti

to assist the struggling relief effort.

They brought much-needed heavy equipment,

as well as other urgent supplies.

You need to have the right equipment

for the particular kind of problem

that you’re dealing with, right?

Whether it’s robots that help you find people

that are buried in an earthquake, or whether

it’s water purification systems, et cetera.

And the right meds for the most likely types of scenarios

that you’re going to encounter in these events.

Aid distribution was chaotic.

U.S. helicopters unloaded boxes of ready-to-eat meals.

They contained powdered food,

but to the Haitians,

they just looked like packets of dust.

Many people threw them away

because no French or Creole-language instructions

explained that they needed to be prepared

by mixing with water.

Despite the fact that the airport was open,

aid groups complained of long delays

in getting vital supplies of food, water and medicine.

Médecins Sans Frontières-- Doctors without Borders,

reported that its cargo plane with 12 tons

of urgently required medical supplies,

had been turned away from the congested airport three times.

One doctor reported that they had been forced

to buy a saw from a local market

so that they could continue to perform amputations.

With 16,000 boots on the ground,

the U.S. Army reported

that 400,000 bottles of water and 300,000 food rations

had been delivered since they first arrived

on the scene the day after the earthquake.

With over a million people left homeless,

those displaced in urban areas were forced to shelter

in flimsy makeshift camps.

Only around 130 people were rescued

from collapsed buildings by international rescue teams.

Two weeks after the initial earthquake,

the search for survivors was largely abandoned,

and all efforts now focused on retrieving the dead.

250,000 to 300,000 die,

300,000 are injured

and 1.5 million are homeless.

Although billions were raised through international efforts

from both government and charitable bodies,

Haiti is still gripped by grinding poverty

and underinvestment.

But the fact that young people are now being trained

in safe building practices

shows that Haitians are trying to learn lessons

from those terrible events.

Proper training of the local population

is crucial to the success of any emergency response effort.

Regular drills must be undertaken

to ensure that people are adequately prepared

for the likely event that another deadly earthquake

will strike in the future.

When it comes to lessons learned from past disasters,

few places can rival the city

that we focus on next in this episode.

On the afternoon of the 19th of September, 2017,

a magnitude 7 earthquake, the same force

as the one that struck Haiti, hit Mexico City.

Dozens of buildings collapsed,

and a total of 369 people lost their lives.

But in 1985, exactly 32 years prior to that day,

an earthquake in the same city

caused more than 400 buildings to collapse,

killing over 10,000 people and leaving 5 million

with no power or water.

In the last 35 years, we have had

two very important events in Mexico City.

One was the ’85 earthquake.

That earthquake was a subduction earthquake.

It was produced on Lazaro Cardenas in Michoacan

around 250 kilometers from the city.

That earthquake was very destructive,

we had a lot of damaged buildings

and a lot of collapsed buildings.

A lot of people died in that earthquake

and it was combined with the aftershock the day after.

So it has been

the most destructive earthquake in the city.

Why was there so much more death and destruction

in the 1985 earthquake?

The difference between the two disasters

has been largely attributed

to a change in the building regulations

and the introduction of an early warning system.

XYOLI PERéZ: So after the 1985 earthquake, the Michoacan earthquake,

there was the need of establishing

an early warning system for Mexico City.

In the early hours of the 19th

of September, 1985,

just as millions of people were getting ready for their day,

Mexico City was struck by a magnitude 8 earthquake,

one of the most powerful ever to hit the area.

It was also one of the longest.

The terrified inhabitants had to endure intense shaking

that lasted for nearly three minutes.

The quake extended over a vast area.

According to the U.S. Geological Survey,

tremors were felt as far away as Guatemala City

and Houston Texas, over 1500 kilometers from the epicenter.

The quake occurred along a vast subduction zone

which is part of the Middle American Trench.

This is the eastern part of what is arguably

the most dangerous series of fault lines in the world--

the Ring of Fire, a volatile strip which runs

in a 40,000-kilometer horseshoe

around the edge of New Zealand in the Pacific Ocean,

passing Indonesia, the Philippines,

Japan and Russia,

across to Canada, the Pacific coast of America,

Mexico and down the eastern coast of South America.

Roughly 90 percent of all earthquakes

occur along this ring.

Although, the epicenter of the earthquake

was in Michoacán...

the majority of the damage occurred in Mexico City,

over 300 kilometers away.

How could an earthquake so far away

prove to be so catastrophic?

The answer lies in the very dawn of civilization,

when the Aztecs settled in Mexico

and developed a vast empire.

They created their capital

on two small islands in Lake Texcoco.

By 1519, it was home

to an estimated 400,000 inhabitants.

When the Spanish conquered the Aztecs,

they destroyed the city

and built a new one on the ruins.

After Mexico’s independence,

this ancient site became its capital.

Mexico City, it’s a very unique place in the world.

It sits atop a lake bed zone,

very high water content.

We call them saturated soil.

That lake was drained over time.

The 1960s is when it was drained

100 percent, the lake is gone.

Unfortunately, what that meant is

people moved into that area

as the lake was drained,

so now people live where there used to be a lake.

What that means is, for earthquakes,

is that it amplifies the signal greatly because it’s a basin

and they’re basically sitting on what used to be mud.

We study the subsidence,

so what happens is, in Mexico City,

because of the lake sediment, is moving downward

every year by about 35 centimeters.

In every place in the world that they study seismology,

they talk about Mexico City.

The earthquake caused

widespread catastrophic damage.

Several old hotels, including the Regis, Versailles,

and Romano fell to the ground.

Gas mains were fractured, causing fires and explosions.

Many multi-story buildings collapsed completely.

Nearly 7000 were seriously damaged.

Fortunately, the quake struck

when many were still commuting to work.

Thirteen hospitals were destroyed.

In the immediate aftermath, 40 percent of the population

in Mexico City had no electricity,

45 percent were without water.

President Miguel de la Madrid initially refused offers

of help from the international community.

He said that Mexico was well able to cope

with the disaster on its own.

Volunteers from areas of the city

that had escaped largely undamaged

went to the aid of their fellow citizens

who had not been so fortunate.

Residents spontaneously organized themselves

into brigades, such as the Moles Rescue Brigade,

to help in the search for survivors.

We never knew each other.

We started helping in the collapsed structures

and started working and making friends and telling,

"Well, we’ll meet here tomorrow

and we’ll start working."

There were extraordinary scenes of unity

from the city’s inhabitants,

where many lent a helping hand to their neighbors.

We started working with the people

to save people and their belongings.

Overall, there was a feeling of solidarity,

which was remarkable in such a vast, sprawling city.

As the scale of the disaster became evident,

thousands took to the streets in protest,

demanding assistance.

Following the demonstrations,

the government’s attitude to foreign aid softened.

Mexico began to accept offers

of money and help from many countries.

Five days after the earthquake,

Nancy Reagan visited the stricken city.

She delivered a letter of sympathy

from the U.S. president

and a down payment of $1 million

on future American aid.

Hope of finding any last survivors faded.

It was thought that no one could remain alive

under the fallen masonry for more than a week.

But rescuers working amongst the tangled wreckage

of a maternity hospital were convinced

that there were still people left alive in there.

What happened next came to symbolize

a spirit of resilience and togetherness

in the face of terrible adversity.

The 12-story tower of the Juarez Hospital

was built in 1970.

At the time of the earthquake, the hospital was nearly full,

and more than 700 patients and doctors

were believed to have been trapped inside.

Rescue teams from several countries

as well as volunteers and family members of the victims,

worked non-stop for days, searching for survivors.

Many bodies had already been found,

but with the help of ultra- sensitive listening devices,

people heard noises that gave them a small glimmer of hope.

Images of rescue workers using pickaxes to dig their way

to buried survivors were beamed around the world.

A week after the hospital collapsed,

an 8-day old baby girl and a 33-year-old man

were pulled alive from amongst the rubble.

As dusk fell, another infant

was pulled alive from the wreckage.

In all, more than a dozen babies

were rescued from the collapsed hospital.

They became a symbol of hope

for a devastated nation

and have been known ever since as the ’miracle babies’.

Across Mexico City, many people

were rescued alive from the debris.

While thousands received medical treatment,

5000 bodies were recovered

from the rubble of the shattered city.

But those were only the total number

of legally certified deaths.

Approximately 250,000 people were left without shelter.

The total cost of the disaster to the Mexican economy

was estimated to be more than $4 billion.

In the first weeks after the earthquake,

720,000 tons of debris were removed.

The disastrous 1985 earthquake led to the introduction

of much tougher building regulations,

equal or superior to those found

anywhere in the world, and to the formation

of well-trained emergency search-and-rescue brigades.

Well, there’s a lot of challenges

with disaster preparedness.

The challenges involve trying to figure out

which disaster is more likely to cause more damage.

What is the chance that something can happen,

and if it happens, how bad is it likely to be?

The catastrophe also resulted in the establishment

of a seismic alarm system which provides advanced warning

whenever it senses movement on the Pacific Coast.

The main idea of the early warning system is that

we have a lot of devices that measure the movements

along the Pacific Coast and the idea is,

when those devices record a very large motion,

they send a signal to Mexico City.

So, the idea is you could use that

to give a little bit of warning to people

for when the real hammer of the surface waves arrive.

The early warning system

received a major test

on the night of the 7th of September, 2017.

Mexico was rocked by a powerful magnitude 8.2 earthquake,

nearly 725 kilometers from Mexico City.

The early warning system worked exactly as planned.

Sirens went off a full two minutes

before the first tremors reached the city.

Buildings shook,

but the earthquake was so far away

that there was little damage.

Twelve days later,

Mexico City took part in the annual drill

to mark the anniversary of the fateful 1985 earthquake.

Sirens wailed but the atmosphere was calm.

After all,

this drill happened every year.

When the sirens went off again a few hours later,

many believed it was still part of the earlier drill.

But they were wrong.

Within seconds, the city was struck

by a magnitude 7.1 earthquake.

The intense shaking lasted for only 20 seconds,

but in that time, over 40 buildings collapsed,

hundreds were killed, and thousands injured.

It was 7.1 on magnitude scale but it was too near.

It was just like 120km from the center of the city.

That means that from the south part of the city,

because the city is very large,

it was just like 100 km, for example, from Xochimilco.

We have movements in differing ways,

which cause a lot of problems to infrastructure,

to buildings, to the metro system over there...

In the neighborhood of Roma Norte,

an entire office building collapsed.

Survivors were taken to hospital

but there were fears that many people

were still trapped inside.

Construction workers from a nearby site rushed to help.

The government quickly declared a state of emergency.

Federal police were swiftly deployed

with 3000 personnel taking to the streets.

From all over the damaged areas of the city

there were reports of gas leaks and fires.

Amid the increasing noise and clamor

of a hectic rescue operation, it became clear

that the faint sounds alerting search parties

to the presence of survivors, could be missed.

Rather than yelling, rescuers developed

a system of hand signals.

A fist in the air was a call for immediate silence.

The gesture would be repeated by everyone around,

silently spreading the message through the crowd.

The call for everyone to stop moving

was an open palm in the air.

And a single finger in the air meant "back to work".

While in parts of the city that had not been affected,

there was an eerie silence.

Businesses had closed, and the normally congested

rush-hour streets were mostly empty.

But there was frantic activity

at disaster sites.

When rescuers arrived at the Enrique Rebsamen School,

they discovered a harrowing scene:

Dozens of children and teachers had been buried

when the three-story school building collapsed in on them.

As rescuers clawed

at the concrete with their bare hands,

they could hear the screams of children

trapped beneath the rubble.

President Enrique Peña Nieto later visited the school

to mourn the 20 children and two staff members

who had lost their lives.

Distraught parents clung to the hope

that their missing children could still be saved.

But tragically, only two children

were pulled out of the wreckage.

In the Condesa area,

a man was rescued after being trapped under the wreckage

of an apartment building for 22 hours.

Rescuers had heard him screaming for help all night.

The Mexican president announced

that the damage caused by the earthquakes

could cost upwards of $2 billion.

But while there was loss of life and significant damage,

it was nowhere near as bad as in the 1985 earthquake.

Millions of dollars had been spent

to reinforce older buildings across the city.

Buildings can be affected by earthquakes,

but designing them correctly

can eliminate a lot of the problems.

The construction codes in Mexico City

actually are one of the most rigorous codes in the world,

and since the earthquake of 1985, there has been

a lot of specific points that were studied by people

from UNAM and the engineering institute

that are specialists that have helped the developing

of more rigorous and more strict construction codes.

In Mexico City, strict building controls

are only a part of the system in place to help them

become better prepared for future earthquakes.

Teams of staff in the emergency services

practice earthquake simulations throughout the year

so they can respond immediately.

But most important of all have been

the huge public-awareness campaigns that have trained

the residents of Mexico City to understand

exactly what to do when they hear the sirens.

But we are still behind other cities,

like, for example, Tokyo,

Los Angeles, and San Francisco,

because in those places, people and society are more aware

about how earthquakes can affect the buildings.

For example, in San Francisco, in the science museum,

they have a complete part of the museum

dedicated to the earthquakes.

I believe that Mexico can use those kind of ideas

in order for the people to get more prepared

and more aware about how earthquakes can affect them.

However, the safety measure

that would save most lives,

the ability to accurately predict

when and where an earthquake will strike,

has proved to be stubbornly elusive.

In order to understand the vulnerability of a place,

we need to understand what is the probability

of earthquakes to occur.

Prediction means that you give

the exact time and place of an earthquake.

What we can do, just as we do with the weather,

is we can forecast earthquakes.

Now, we can use a technology called GPS,

the global positioning system, to survey the crust

around a potential earthquake fault.

We know that the Earth is a chaotic system,

and we can say that if we apply chaos theory here,

we are actually never going to be able to predict,

because we never knew and are never going to know what

the initial conditions were on the Earth, unfortunately.

Now we have much more equipment,

not just in the earth, but also in space,

so we can have a lot of measurements,

and hopefully we could find some precursor that allows

to make earthquake predictions.

If we could predict that an earthquake

is going to happen in 20 minutes,

how useful would that be?

Because it’s not enough time to evacuate a city.

What we really need is something

like what we have for hurricanes.

Ideally, we’ll need three days’ warning,

which would probably give us time

to evacuate a large city like Mexico City.

All we can be sure of is that

some of the world’s most populous

and economically significant cities

are situated on or near seismically active fault lines.

For those cities, it is not a question

of "if" an earthquake will strike but "when".

We will always have to live with the threat

of one of Mother Nature’s most unpredictable

and deadly forces,

earthquakes.