TedTest

From the Ted Talk by Alex Gendler: How tsunamis work

Unscramble the Blue Letters

In 479 BC, when Persian soldiers besieged the Greek city of Potidaea, the tide retreated much farther than usual, leaving a convenient invasion route. But this wasn't a stroke of luck. Before they had crossed halfway, the water returned in a wave higher than anyone had ever seen, drowning the acteaktrs. The Potiidaeans believed they had been saved by the wrath of Poseidon. But what really saved them was likely the same phenomenon that has destroyed countless others: a tnasmui. Although tsunamis are commonly known as tidal waves, they're actually unrelated to the tidal atiicvty caused by the gravitational forces of the Sun and Moon. In many ways, tsunamis are just larger versions of raulegr wveas. They have a trough and a csret, and consist not of moving water, but the movement of energy through water. The defcinefre is in where this energy comes from. For noarml oaecn waves, it comes from wind. Because this only affects the surface, the waves are limited in size and speed. But tnimsuas are csuaed by energy originating underwater, from a volcanic eruption, a submarine lndidsale, or most commonly, an earthquake on the ocean floor caused when the teotcinc plates of the Earth's surface slip, releasing a massive amount of energy into the water. This energy travels up to the surface, dipinscalg water and raising it above the normal sea level, but gitvray pulls it back down, which makes the energy ripple outwards horizontally. Thus, the tsunami is born, moving at over 500 melis per hour. When it's far from shore, a tsunami can be barely detectable since it moves through the entire depth of the water. But when it reaches shallow water, something called wave shoaling ouccrs. Because there is less wtear to move through, this still massive amount of eergny is compressed. The wave's speed slwos down, while its hhiegt rises to as much as 100 feet. The word tsunami, Japanese for "harbor wave," comes from the fact that it only seems to appear near the caost. If the tgruoh of a tsunami reaches shroe first, the water will withdraw farther than normal before the wave hits, which can be misleadingly dangerous. A tsunami will not only dorwn people near the coast, but level buildings and teres for a mile inland or more, especially in low-lying areas. As if that weren't enough, the water then retreats, dragging with it the newly created debris, and anything, or anyone, unfortunate enough to be caught in its path. The 2004 inidan Ocean tsunami was one of the deadliest natural disasters in history, killing over 200,000 people throughout stouh Asia. So how can we protect ourselves against this destructive force of nature? ppolee in some areas have attempted to stop tsunamis with sea walls, flood gates, and chanlens to divert the water. But these are not always effective. In 2011, a tsunami surpassed the flood wall protecting Japan's Fukushima Power Plant, causing a nuclear disaster in addition to claiming over 18,000 lievs. Many scientists and policy makers are instead focusing on early ditceteon, monitoring underwater pressure and sisiemc activity, and esianithblsg global communication networks for quickly distributing alerts. When nature is too powerful to stop, the safest course is to get out of its way.

Open Cloze

In 479 BC, when Persian soldiers besieged the Greek city of Potidaea, the tide retreated much farther than usual, leaving a convenient invasion route. But this wasn't a stroke of luck. Before they had crossed halfway, the water returned in a wave higher than anyone had ever seen, drowning the _________. The Potiidaeans believed they had been saved by the wrath of Poseidon. But what really saved them was likely the same phenomenon that has destroyed countless others: a _______. Although tsunamis are commonly known as tidal waves, they're actually unrelated to the tidal ________ caused by the gravitational forces of the Sun and Moon. In many ways, tsunamis are just larger versions of _______ _____. They have a trough and a _____, and consist not of moving water, but the movement of energy through water. The __________ is in where this energy comes from. For ______ _____ waves, it comes from wind. Because this only affects the surface, the waves are limited in size and speed. But ________ are ______ by energy originating underwater, from a volcanic eruption, a submarine _________, or most commonly, an earthquake on the ocean floor caused when the ________ plates of the Earth's surface slip, releasing a massive amount of energy into the water. This energy travels up to the surface, __________ water and raising it above the normal sea level, but _______ pulls it back down, which makes the energy ripple outwards horizontally. Thus, the tsunami is born, moving at over 500 _____ per hour. When it's far from shore, a tsunami can be barely detectable since it moves through the entire depth of the water. But when it reaches shallow water, something called wave shoaling ______. Because there is less _____ to move through, this still massive amount of ______ is compressed. The wave's speed _____ down, while its ______ rises to as much as 100 feet. The word tsunami, Japanese for "harbor wave," comes from the fact that it only seems to appear near the _____. If the ______ of a tsunami reaches _____ first, the water will withdraw farther than normal before the wave hits, which can be misleadingly dangerous. A tsunami will not only _____ people near the coast, but level buildings and _____ for a mile inland or more, especially in low-lying areas. As if that weren't enough, the water then retreats, dragging with it the newly created debris, and anything, or anyone, unfortunate enough to be caught in its path. The 2004 ______ Ocean tsunami was one of the deadliest natural disasters in history, killing over 200,000 people throughout _____ Asia. So how can we protect ourselves against this destructive force of nature? ______ in some areas have attempted to stop tsunamis with sea walls, flood gates, and ________ to divert the water. But these are not always effective. In 2011, a tsunami surpassed the flood wall protecting Japan's Fukushima Power Plant, causing a nuclear disaster in addition to claiming over 18,000 _____. Many scientists and policy makers are instead focusing on early _________, monitoring underwater pressure and _______ activity, and ____________ global communication networks for quickly distributing alerts. When nature is too powerful to stop, the safest course is to get out of its way.

Solution

activity
people
seismic
indian
regular
crest
miles
shore
difference
lives
height
drown
landslide
gravity
energy
tsunami
tectonic
water
normal
ocean
trees
attackers
detection
south
coast
displacing
establishing
occurs
tsunamis
trough
waves
caused
channels
slows

Original Text

In 479 BC, when Persian soldiers besieged the Greek city of Potidaea, the tide retreated much farther than usual, leaving a convenient invasion route. But this wasn't a stroke of luck. Before they had crossed halfway, the water returned in a wave higher than anyone had ever seen, drowning the attackers. The Potiidaeans believed they had been saved by the wrath of Poseidon. But what really saved them was likely the same phenomenon that has destroyed countless others: a tsunami. Although tsunamis are commonly known as tidal waves, they're actually unrelated to the tidal activity caused by the gravitational forces of the Sun and Moon. In many ways, tsunamis are just larger versions of regular waves. They have a trough and a crest, and consist not of moving water, but the movement of energy through water. The difference is in where this energy comes from. For normal ocean waves, it comes from wind. Because this only affects the surface, the waves are limited in size and speed. But tsunamis are caused by energy originating underwater, from a volcanic eruption, a submarine landslide, or most commonly, an earthquake on the ocean floor caused when the tectonic plates of the Earth's surface slip, releasing a massive amount of energy into the water. This energy travels up to the surface, displacing water and raising it above the normal sea level, but gravity pulls it back down, which makes the energy ripple outwards horizontally. Thus, the tsunami is born, moving at over 500 miles per hour. When it's far from shore, a tsunami can be barely detectable since it moves through the entire depth of the water. But when it reaches shallow water, something called wave shoaling occurs. Because there is less water to move through, this still massive amount of energy is compressed. The wave's speed slows down, while its height rises to as much as 100 feet. The word tsunami, Japanese for "harbor wave," comes from the fact that it only seems to appear near the coast. If the trough of a tsunami reaches shore first, the water will withdraw farther than normal before the wave hits, which can be misleadingly dangerous. A tsunami will not only drown people near the coast, but level buildings and trees for a mile inland or more, especially in low-lying areas. As if that weren't enough, the water then retreats, dragging with it the newly created debris, and anything, or anyone, unfortunate enough to be caught in its path. The 2004 Indian Ocean tsunami was one of the deadliest natural disasters in history, killing over 200,000 people throughout South Asia. So how can we protect ourselves against this destructive force of nature? People in some areas have attempted to stop tsunamis with sea walls, flood gates, and channels to divert the water. But these are not always effective. In 2011, a tsunami surpassed the flood wall protecting Japan's Fukushima Power Plant, causing a nuclear disaster in addition to claiming over 18,000 lives. Many scientists and policy makers are instead focusing on early detection, monitoring underwater pressure and seismic activity, and establishing global communication networks for quickly distributing alerts. When nature is too powerful to stop, the safest course is to get out of its way.

Frequently Occurring Word Combinations

ngrams of length 2

collocation	frequency
massive amount	2

Important Words

activity
addition
affects
alerts
amount
areas
asia
attackers
attempted
barely
bc
believed
besieged
born
buildings
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claiming
coast
commonly
communication
compressed
consist
convenient
countless
created
crest
crossed
dangerous
deadliest
debris
depth
destroyed
destructive
detectable
detection
difference
disaster
disasters
displacing
distributing
divert
dragging
drown
drowning
early
earthquake
effective
energy
entire
eruption
establishing
fact
feet
flood
floor
focusing
force
forces
fukushima
gates
global
gravitational
gravity
greek
halfway
height
higher
history
hits
horizontally
hour
indian
inland
invasion
japanese
killing
landslide
larger
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level
limited
lives
luck
makers
massive
mile
miles
misleadingly
monitoring
moon
move
movement
moves
moving
natural
nature
networks
newly
normal
nuclear
occurs
ocean
originating
outwards
path
people
persian
phenomenon
plant
plates
policy
poseidon
potidaea
potiidaeans
power
powerful
pressure
protect
protecting
pulls
quickly
raising
reaches
regular
releasing
retreated
retreats
returned
ripple
rises
route
safest
saved
scientists
sea
seismic
shallow
shoaling
shore
size
slip
slows
soldiers
south
speed
stop
stroke
submarine
sun
surface
surpassed
tectonic
tidal
tide
travels
trees
trough
tsunami
tsunamis
underwater
unfortunate
unrelated
usual
versions
volcanic
wall
walls
water
wave
waves
ways
wind
withdraw
word
wrath