Waves that travel across the ocean
as fast as a jet.
They're 30 m (100 ft) tall.
And can uproot trees
and move houses.
So why do people always think
they can outrun them?
Tsunamis are caused
by extreme underwater motion
that can be caused by earthquakes
or volcanoes.
This results in massive waves
that can crash into coastal cities
and cause critical damage
to buildings and roads.
In 2004,
the Indian Ocean tsunami killed
an estimated 230,000 people
in over a dozen countries,
all in just a few hours.
This demonstration of lethal power
shook the world,
while exposing a lack of
proper warning systems
and general unawareness of the signs
of an impending tsunami.
But in 2011,
a well-prepared Japan
was hit by a tsunami.
16,000 people were killed.
Seawalls and modern tsunami-resistant
buildings likely saved thousands of lives,
but couldn't save them all.
A prepared community is a good first step
to survive a tsunami,
but you need to do your part as well.
Today we want you to avoid
the mistakes that could kill you
in case of a tsunami occurring near you.
Here's what you should not do.
You're at the beach
when the waters suddenly recede.
You better follow the water
and investigate, right?
Wrong.
Don't start walking further out
from the shore.
Doing so means putting yourself
too close to the impending action.
It's hard to interpret the speed of a wave
when you are on the beach,
and when you get too close,
you lose your perspective.
When you finally realize
its size and speed,
it will be too late.
You'll be overtaken by the enormous wave.
But not all tsunamis
will have receding water,
so how else do you tell
if you're in danger?
It's common for there to be
emergency centers that specialize
in detecting
and alerting people
about impending tsunamis.
If you're in a coastal city
and feel an earthquake,
prepare to get further inland
and stay alert.
Keep a smartphone or radio close
to learn about any announcements.
If a tsunami watch is issued,
make sure you and your family
are prepared to evacuate.
If a tsunami warning is issued,
get moving.
Immediately.
You may also hear a noise
like a plane, or whistling.
This is another cue to get out of there.
Once a tsunami warning is issued,
you have a maximum of 30 minutes
to get to safety.
But don't take this for granted.
It doesn't always take that long
for a tsunami to reach shore.
Sometimes it could only be a few minutes
or even seconds
before a wave washes you away.
If you are driving
and become stuck in a traffic jam,
get out of the car
and run for higher ground.
The waves can include uprooted trees
or even boulders,
so your vehicle might not be able
to save your life.
This deadly natural disaster can flood
as far as 10 km (6 mi) inland
within approximately six minutes.
Outrunning the tsunami is not an option.
Find a building
and climb to at least the third floor.
Hide somewhere away from windows.
A large hotel with several stories
would be ideal.
Never leave your house or shelter
while the tsunami is happening.
And do not return to low-lying areas
after the first wave.
Tsunamis generate multiple waves,
and the first wave
is not always the biggest.
A small wave might be 2 m (6.5 ft)
and would carry more than enough force
to knock you down.
Following a March 11,
2011 earthquake in Japan,
a tsunami hit
the Northern California coast.
After the major wave hit,
a man named Dustin Douglas Weber
came back to take pictures
and got swept up in a second wave.
Three weeks later,
his body washed up
at Fort Stevens State Park in Oregon,
483 km (300 mi) away.
Remain on higher ground
for at least three hours,
or until authorities announce that it is
safe to return to low-lying areas.
Bridges may be compromised
and collapse,
so take alternate routes to go home.
If your house is flooded,
stay away.
It could collapse when you get inside.
Before reentering,
your home must be checked for gas leaks,
fires and electrical hazards.
Even if your house seems unaffected,
don't drink tap water until it's been tested
for contamination.
It's been a long and traumatic day,
but it might not be over.
Do not underestimate the potential
for secondary disasters
like landslides or aftershocks.
Prepare a disaster kit
with first aid supplies,
drinking water
and enough food to last
for at least three days.
You survived thanks to
your city's safety protocols
and quickly identifying the signs
of an impending tsunami.
But the devastating power of water
can cause damage
even far from the coast.
What if the dam that protects your city
suddenly collapses?
Find out what to do,
here.