A series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions (including detonations, landslides, glacier calvings, meteorite impacts and other disturbances) above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water by a large event.
3. INDEX
o WHAT IS TSUNAMI?
o CAUSES OF TSUNAMI
1.) EARTHQUAKES
2.) LANDSLIDES
3.) VOLCANIC ERUPTIONS
o TSUNAMI WARNINGS
o PREVENTIONS
o EFFECTS
o FACTS
o SOME DEADLIEST TSUNAMIS
1.) The 2011 Japan Tsunami
2.) The 2004 Indian Ocean Tsunami
o BIBLIOGRAPHY
4. WHAT IS
TSUNAMI?
• A tsunami [(t)soo-NAH-mee lit. 'harbour wave'] is a
series of waves in a water body caused by the
displacement of a large volume of water, generally in
an ocean.
• It is caused by an underwater earthquake, landslide, or
volcanic eruptions and other underwater
explosions (including detonations, landslides, glacier
calvings, meteorite impacts and other disturbances).
• Tsunami waves do not resemble normal undersea
currents or sea waves because their wavelength is far
longer.
5. A tsunami is not a single wave but a series of waves. The
first wave in a tsunami is not necessarily the most
destructive. Tsunamis are not tidal waves.
Tsunami waves can be very long (60 miles, or 100
kilometers) and be as far as one hour apart. They are able
to cross entire oceans without great loss of energy. The 2004
Indian Ocean tsunami traveled 3,000 miles to Africa, arriving
with sufficient force to kill people and destroy property. It was
among the deadliest natural disasters in human history,
with at least 230,000 people killed or missing in 14 countries
bordering the Indian Ocean.
Where the ocean is deep, tsunamis can travel unnoticed on
the surface at speeds up to 500 miles an hour crossing an
ocean in a day or less.
A tsunami may be less than a foot (30 centimeters) in height
on the surface of the open ocean, which is why they are not
noticed by sailors. Once a tsunami reaches shallow water
near the coast, it is slowed down. The top of the wave moves
faster than the bottom, causing the sea to rise dramatically.
The most damaging tsunami on record before 2004 was the
one that killed an estimated 40,000 people in 1782 following
an earthquake in the South China Sea.
The Pacific is by far the most active tsunami zone,
according to the U.S. National Oceanic and Atmospheric
Administration (NOAA).
6. WHAT
CAUSES
TSUNAMI?
The principal generation mechanism of a tsunami is
the displacement of a substantial volume of water or
perturbation of the sea.
This displacement of water is usually attributed to:
EARTHQUAKES
Most tsunami are caused by large earthquakes on
the sea floor when slabs of rock move past each
other suddenly, causing the overlying water to move.
The resulting waves move away from the source of
the earthquake event.
7. LANDSLIDES
Landslides can also happen on the
seafloor. Areas of the seafloor that are steep
and loaded with sediment, such as the edge
of the continental slope, are more prone to
undersea landslides.
When an undersea landslide occurs, a large
mass of sand, mud and gravel can move
down the slope. This movement will draw the
water down and may cause a tsunami that will
travel across the ocean.
8. VOLCANIC
ERUPTIONS
Tsunami initiated by volcanic eruptions are less
common. They occur in several ways:
destructive collapse of coastal, island and
underwater volcanoes which result in massive
landslides
pyroclastic flows, which are dense mixtures of
hot blocks, pumice, ash and gas, plunging
down volcanic slopes into the ocean and
pushing water outwards
caldera volcano collapsing after an eruption
causing overlying water to drop suddenly.
9. TSUNAMI WARNING
An earthquake felt near a body of water
may be considered an indication that a
tsunami will shortly follow.
Early warnings come from nearby animals
as they sense danger and flee to higher
grounds.
There are some warning signs of an
impending tsunami, and automated
systems can provide warnings
immediately after an earthquake in time
to save lives. One of the most successful
systems uses bottom pressure sensors,
attached to buoys, which constantly
monitor the pressure of the overlying
water column.
10. PREVENTIONS
First, protect yourself from an Earthquake. Drop, Cover, then Hold
On.
Get to high ground as far inland as possible.
Be alert to signs of a tsunami, such as a sudden rise or draining of
ocean waters.
Listen to emergency information and alerts.
Evacuate: DO NOT WAIT! Leave as soon as you see any natural
signs of a tsunami or receive an official tsunami warning.
Be alert to signs of a tsunami, such as a sudden rise or draining of
ocean waters.
Listen to emergency information and alerts.
If you are in a boat, go out to sea.
Always follow the instructions from local emergency
managers. They provide the latest recommendations based on
the threat in your community.
Know and practice community evacuation plans and map out
your routes from home, work, and play. Pick shelters 100 feet
or more above sea level, or at least one mile inland.
Create a family emergency communication plan that has an
out-of-state contact. Plan where to meet if you get separated.
If you are in a boat, then face the direction of the waves and
head out to sea. If you are in a harbor, then go inland.
11. EFFECTS
• After the rescue of survivors, the primary public health concerns are
clean drinking water, food, shelter, and medical care for injuries.
• Flood waters can pose health risks such as contaminated water and
food supplies.
• Loss of shelter leaves people vulnerable to insect exposure, heat, and
other environmental hazards.
• The majority of deaths associated with tsunamis are related to
drownings, but traumatic injuries are also a primary concern. Injuries
such as broken limbs and head injuries are caused by the physical
impact of people being washed into debris such as houses, trees, and
other stationary items. As the water recedes, the strong suction of
debris being pulled into large populated areas can further cause
injuries and undermine buildings and services.
• Medical care is critical in areas where little medical care exists.
• The contaminated water and food supplies as well as the lack of
shelter and medical care may have a secondary effect of worsening
illnesses that already exist in the affected region.
• Decaying bodies create very little risk of major disease outbreaks.
• The people most at risk are those who handle the bodies or prepare
them for burial.
12. FACTS
Many people were killed by the Indian
Ocean tsunami because they went
down to the beach to view the
retreating ocean exposing the
seafloor. Experts believe that a
receding ocean may give people as
much as five minutes' warning to
evacuate the area.
The Indian Ocean tsunami of 2004 hit
14 countries from Thailand to Africa,
killing around 250000 people.
During the Indian Ocean tsunami of
December 26th 2004, the Jason
satellite altimeter happened to be in
the right place at the right time
Scientists believe that in the year
1700, a tsunami of magnitude 9
occurred in the Pacific Ocean in the
northwest and caused massive
flooding and damage in Japan.
13. The places with the greatest risk of
tsunami are Washington, Oregon,
Hawaii, Alaska and California.
One should not swim in the tsunami
water as the current is always pulling
the person in the opposite direction.
Thucydides, a Greek historian in his
book History of Peloponnesian War,
was the first who associated the
term tsunamis with underwater
earthquakes.
Many scientists believe that a
tsunami created by a meteorite had
occurred on earth 3.5 billion years
back.
14. Scientists predict that the next mega
tsunami will occur in Canary island and will
cause damage up to American coastal
cities like Boston, Miami and New York with
waves as high as 100 feet.
A tsunami that occurred in Lisbon in 1755
killed 90,000 residents within minutes.
Tsunami can poison the mainland with a lot
of salt, causing people to die out of hunger
and disease after the tsunami is gone.
Hawaii in the U.S. is at a greater risk for a
Tsunami. Hawaii gets about one Tsunami
every year and damaging one every seven
years.
The 2011 Japan Tsunami is believed to be
world’s most expensive disaster in history.
