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Tsunami:
Magnitude of Terror
Causes
JNANA PRABODHINI
Contents
• Plate Tectonics
• Tsunami Formation
• Indian Ocean Earthquake
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Causes
Plate Tectonics
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Plate Tectonics
• In the 20th century, a German meteorologist named
Alfred Wegener proposed the Continental Drift Theory
which states that the surface of the Earth actually
consisted of plates which were in constant slow motion.
• According to this theory, the Earth’s surface is broken
into eight major plates and several other smaller ones.
The edges of these plates are known as the plate
boundaries, and are areas with intense geologic activity,
e.g. earthquakes, volcanic activities and folding of the
crust.
• These plates are continuously in motion, forming sites of
convergence, divergence and sliding.
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Plates of The World
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Plate Tectonics
• Plate tectonics is a combination of two earlier ideas,
namely the Continental Drift Theory and sea-floor
spreading.
• It states that the earth was actually made up of a huge
continent many hundreds of millions of years ago, called
Pangaea, which broke up into smaller continents to form
the continents today.
• Sea floor spreading is the creation of new oceanic crust
at divergent plate boundaries where two plates move
apart from each other, allowing magma from the mantle
to well up and cool, forming new sea floor.
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Causes
Tsunami Formation
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Tsunami Formation
• Definition
Tsunamis are defined as extremely large ocean waves triggered by
underwater earthquakes, volcanic activities or landslides.
• The word tsunami was coined from the Japanese word "津波",
translating to "harbor wave" in English.
• Tsunamis are sometimes referred to as "tidal waves" by the general
public, which is a misnomer as tsunamis are unrelated to the tides.
• Tsunamis normally occur in Pacific Ocean, and are relatively rare in
areas surrounding the Indian subcontinent.
• The December 26th tsunami disaster is an example of a tsunami
which was triggered by an earthquake.
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Tsunami Formation
• Tsunamis are characterized as shallow-water waves due to their
long periods and wavelengths.
• A wind-generated wave might have a period of ten seconds and a
wavelength of 150 meters, but it is possible for a tsunami to have a
wavelength more than 100 kilometers and a period on the order of
one hour, with a wavelength of only a few centimeters.
• In the Pacific Ocean, where the depth of water is about 4000 meters,
tsunamis travel at about 200 m/s.
• Because the rate of energy loss by the wave is inversely
proportional to its wavelength, tsunamis not only spread at high
speeds, they can also travel large distances with little energy loss.
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Tsunami Formation
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Tsunamis can be generated when the sea floor suddenly displaces the
overlying water vertically.
Tectonic earthquakes are a kind of earthquake that can caused that.
When they occur beneath the sea, the water above the deformed area
is displaced from its equilibrium position.
Waves are formed as the displaced water mass, acting under the force
of gravity, tries to regain equilibrium.
When large areas of the sea floor elevate or subside, a tsunami can be
created.
Large vertical movements of the earth's crust can occur at plate
boundaries.
These boundaries are called faults.
For example, at the boundaries of the Pacific Ocean, denser oceanic
plates slip under the less dense continental plates in a process known
as subduction.
Subduction earthquakes are particularly effective in generating
tsunamis because they provide much force and disturbances deep
underwater.
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Tsunami Formation
• As a tsunami leaves the deep ocean and travels toward the shallow
coast, it transforms.
• A tsunami moves at a speed related to the water depth, therefore
the tsunami slows as the water depth decreases.
• The tsunami's energy flux, being dependent on both its wave
speed and wave height, remains nearly constant.
• As a result, the tsunami's speed decreases as it travels into
shallower water, and its height increases.
• Because of this shoaling effect, a tsunami, unobvious at sea, may
heighten to several meters or more near the coast.
• When it reaches the coast, it may appear as a rapidly rising or falling
tide or a series of breaking waves.
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Tsunami Formation
• As a tsunami reaches the shore, it begins to lose energy whereby
part of its wave energy is reflected offshore, while the shorewardpropagating wave energy is dissipated through friction and
turbulence.
• In spite of this, tsunamis still reach the coast with tremendous
amounts of energy
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Causes
Indian Ocean Earthquake
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Indian Ocean Earthquake
Statistics
• Date : 26 December 2004
Origin Time : 00:58 53 s UTC
Latitude/Longitude : 3.267° North / 95.821° East
Depth : 10 km
Magnitude : 9.0
Locality : 255 km SSE of Banda Aceh, Northern Sumatra
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Official Report
• The December 26 earthquake occurred as the
result of thrust-faulting.
• Preliminary locations of larger aftershocks
following the megathrust earthquake show that
approximately 1200 km of the plate boundary
slipped as a result of the earthquake.
• From the size of the earthquake, it is likely that
the average displacement on the fault plane was
about 15 meters.
• The sea floor overlying the thrust fault would
have been uplifted by several meters as a result
of the earthquake.
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Comparison
• For comparison, the world's largest recorded earthquakes
have been listed below.
• They have all been megathrust events, occurring where one
tectonic plate subducts beneath another.
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These include:
1960 Chile earthquake (Magnitude 9.5)
1964 Prince William Sound, Alaska earthquake (Magnitude
9.2)
1957 Andreanof Islands, Alaska (Magnitude 9.1)
1952 Kamchatka earthquake (Magnitude 9.0)
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Tsunami:
Magnitude of Terror
Effects
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Contents
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Damage to Countries
Death Toll
Economy
Environment
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Effects
DAMAGE TO COUNTRIES
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Indonesia
• The epicenter of the Earthquake was located some 160km west of
Sumatra and nearly all the casualties and damage took place within
the province of Aceh.
• Indonesia's Ministry of Health has confirmed 166,320 dead but this
is not the final count because most regions are still inaccessible and
reports are slow. The Ministry of Foreign Affairs has stated that up to
100,000 are missing. In addition, the UN estimates that 655,000
people are homeless and sheltering in scattered refugee camps
across the province.
• Ten metre tall waves passed the northern tip of Sumatra to turn
southwards towards the Straits of Malacca and strike along the
northeast coast.
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Indonesia
• Nothing is left standing there and the estimated number
of survivors is placed between two and seven hundred
out of an original population of ten thousand.
• Other towns affected include Calang, Meluboh,
Teunmon and numerous others. Most villages are simply
destroyed or are too remote
• The nearby town of Leupung has been obliterated by the
tsunami. Nothing is left standing there and the estimated
number of survivors is placed between two and seven
hundred out of an original population of ten thousand.
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Sri Lanka
• An island nation situated in the Indian Ocean, Sri
Lanka was the 2nd worst hit by the tsunami.
• However, in terms of country size, Sri Lanka was
in fact hit harder by the tsunami than Indonesia
because most of its coastline was hit by the
deadly waves.
• Sri Lankan authorities report 30,196 confirmed
deaths as of 3 January 2005 after the island was
hit by the tsunami.
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Sri Lanka
• Even a train, the Sea Queen, moving between Colombo
and Galle was struck by the killer waves, killing 1,300
onboard out of the 1,600 passengers.
• The agricultural sector has been adversely affected by
the aftermath of the tsunami. 259 hectares of paddy land
along the coast were destroyed.
• Furthermore, the paddy lands which were flooded with
salt water cannot be used for cultivation due to the
salinity of the soil. Large numbers of agricultural
machinery have been destroyed and canals and drains
have been blocked.
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India
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In terms of the number of casualties, India was the 3rd worst hit country
partly because a large section of its coastline was hard hit by the tsunami.
The areas that were hit included the state of Tamil Nadu, Andhra Pradesh,
Kerala, Pondicherry and the Andaman and Nicobar islands.
With a death toll of 7,793, the state of Tamil Nadu was no doubt the worst
hit on the mainland.
In the Nagapattinam district alone there were 5,525 casualties, with entire
villages having been destroyed.
The Kanyakumari district has had 808 deaths and the Cuddalore district 599,
the state capital Chennai 206 and Kancheepuram district 124.
• The casualties in Kanyakumari include pilgrims taking a holy dip in
the sea and visitors to the Vivekananda Rock Memorial. People
playing and taking a Sunday morning stroll along the Marina beach
in Chennai were washed away.
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India
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In addition, the fishing villagers who lived along the shore and those out at
sea were washed away as well. In Velankanni, in the district of Nagapttinam,
most of the casualties were people visiting the Basilica of the Virgin Mary for
Christmas and the residents of the town.
Operations at the nuclear power plant at Kalpakkam were suspended after
sea water gushed into a pump station.
There were no reports of any radiation leakage or damage to the reactor but
100 casualties were reported.
The official death toll for the Andaman and Nicobar islands is 812, and
about 7,000 are still missing, presumed dead.
At least one fifth of the population of the Nicobar islands are amongst the
casualties.
Entire islands were washed away and communications have yet been
restored with the Nancowry group of islands, some of which have been
completely submerged, leaving the total number people out of contact at
7,000.
Thailand, Malaysia, Myanmar , Bangladesh were also affected.
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Effects
Death Toll
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Death Toll
Country
where
deaths
occurred
Deaths
Confirmed Estimated1
Injured
Indonesia
173,981
220,000
~100,00
0
Sri Lanka
38,195
38,195
15,686
India
10,744
16,413
Thailand
5,305 3
Somalia
Missing Displaced
6,245
23,000+
400,000700,000
2
~573,000
-
5,669
380,000
11,000
8,457
4,499
-
150+
298
-
-
5,000
Myanmar
(Burma)
59
2,500
45
7,000 4
3,200
Malaysia
68 – 74
74
299
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Maldives
82
108
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26
12,000 –
22,000
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Death Toll
1– 3
3
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10
10+
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Bangladesh
2
2
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South Africa
25
2
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Kenya
1
2
2
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Yemen
1
1
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Madagascar
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1,000+
Total 228,601+ ~288,608 ~125,000
~40,000
~1.5 million
Seychelles
Tanzania
Note: All figures are approximate and subject to change. For more details on specific countries, click the country name in the first column.
1 Includes those reported under 'Deaths'. If no seperate estimates are available, the number in this column is the same as reported under
'Deaths'.
2 Includes approximately 19,000 missing people declared by Tamil Tiger authorities from regions under their control
3 Data includes at least 2,464 foreigners.
4 This number of missing includes citizens of Myanmar who have fled into Thailand and who have been deported back to Myanmar without
papers.
5 Does not include South African citizens who died outside of South Africa (eg, tourists in Thailand).
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Effects
Economical Impact
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Economical Impact
• The immediate relief needs in the affected countries in the Indian
Ocean are gigantic and complicated, and there will be a long term
need for rebuilding in these areas.
• The disaster is complicated because there are the effects of the
earthquake near the epicenter (Banda Aceh) and the widespread
effects of the tsunami wave.
• The effects are likely to be most severe and apparent for island
economies and countries/cities dependent on the sea and near the
epicenter of the earthquake (Banda Aceh, Andaman and Nicobar
Islands, Maldives).
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Undesirable Effects
• For the many indigenous fishermen who have no other
skills, can no longer depend on fishing as a means of
survival for the time being.
• The fish stock has been depleted, as would the
fishermen's money. Also, the many of the fishermen's
families would have lost their sole breadwinners,
together with the fishing boats and equipment, adding on
to their already heightening problems.
• The tsunamis that affected the coast of Thailand,
Indonesia and the Maldives has destroyed much of the
marine biology there, also damaging the ecosystem
severely.
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Undesirable Effects
• Millions of fish were swept ashore by the huge
waves, and many more will continue to die,
being unable to survive in the severely damaged
habitat left in the wake of the tsunami.
• The marine ecosystem is hence likely to have
been affected badly, with the predators up the
food chain, such as dolphins and sharks, dying
out due to the lack of food. Many species will not
be able to adapt to the sudden change in their
lifestyle and will inevitably die.
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Undesirable Effects
• Fish is also a popular food in these countries
due to the affected countries being surrounded
by water, and the sudden lack of fish and its
important nutrients may pose a problem for the
people used to having fish at every other meal.
• Seafood farms in countries such as Thailand
would also have been damaged, with their
owners suffering enormous losses.
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Undesirable Effects
• Tropical rainstorms in Aceh province of
Indonesia and flooding along Sri Lanka's lowlying coast also hampered aid deliveries.
• The damage to human and animal life was also
tremendous, leaving an estimated 150,000
people dead in Indonesia alone. The latest total
death toll is expected to be over 225,000, one of
the largest dealt by a tsunami in history.
• When the sheer force of a incoming tsunami
obliterates everything in its path, it also clears
away roads and railways, hampering rescue
efforts.
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Undesirable Effects
• Furthermore, the huge mass of water also broke sewage and water
pipes, contaminating water and food sources.
• Subsequently, diseases such as cholera, typhoid, dysentery and
dengue then become more rampant.
• People clung on to trees for their dear life; some were rescued, but
some were also swept away, right in front of their relatives and
family members.
• The emotional and mental trauma would remain in all those affected
for years, even if they had escaped a watery grave.
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Undesirable Effects
• As such, potential tourists would have lost
a sense of security in visiting these
countries.
• People would also refrain from visiting the
countries for fear of being affected by
similar incidences due to this lack of
protection.
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Undesirable Effects
• The refugee camps housing the internally displaced people also had
squalid conditions, unfit for living in.
• Hence many wounds were only hastily treated as there was a
shortage of manpower.
• Luckily for the injured, many volunteers from over 10 countries
joined in the relief efforts to provide adequate healthcare services for
them.
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Effects
Environmental Consequences
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Environmental Consequences
• Precious coral reefs and mangrove areas would have been crushed
by the huge tsunami waves that have devastated southern Asia, an
environmental and economic setback that could take years to
reverse.
• When the waves get close to shore, their height is amplified and
they release all their energy, decimating everything in their paths.
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Tsunami:
Magnitude of Terror
Relief Efforts
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Contents
• Emergency Relief
• Rehabilitation
• Reconstruction
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Relief Efforts
Emergency Relief
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Search and Rescue
•
Many countries were quick to respond to the disaster. Some countries
sent military and medical personnel to affected areas. Others provided
military equipment to facilitate the search and rescue operations.
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The tsunami brought about the devastation of transport and
communication infrastructure. Roads were destroyed, blocking off
access via land to some affected areas. Thus, aerial and sea military
transports were required to reach some rural areas.
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The force of the tsunami has altered the landscape of coastal areas,
rendering most conventional topological maps useless. Therefore, ships
with radar capabilities play supporting roles by coordinating the
operations, and carrying out surveillance work.
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Identification of bodies
Searching for missing loved ones
Medical Aid
Provision of Food & Drinking Water
Housing
Education
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Relief Efforts
Rehabilitation
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Volunteer Work
• Volunteers can provide help to the tsunami victims in many different
ways. Some help in the orderly distribution of food, clothes, drinking
water and medicine and other basic necessities.
• Some help clean up the debris and search for the missing. While
others bury or cremate the dead, treat the injured in medical camps
and relief centers or provide emotional support to those who have
lost family in the tragedy.
• While groups of people from the online community have made
use of their technological expertise to set up websites which
promotes relief aid, or regarding missing persons.
• For the rest of us, according to experts, giving money is the
most practical and effective assistance one can give.
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Relief Efforts
Reconstruction
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Tourism
Fishing Industry
Agriculture
Donations
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Tsunami:
Magnitude of Terror
Future Measures
JNANA PRABODHINI
Contents
• Tsunami Warning System
• Government Policies
• Suggested Precautions
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Future Measures
Tsunami Warning System
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Tsunami Warning System
Definition
A tsunami warning system is a system to detect tsunamis and issue
warnings to prevent loss of life. It consists of two equally important
components: a network of sensors to detect tsunamis and a
communications infrastructure to issue timely alarms to permit
evacuation of coastal areas.
Importance of Tsunami Warning System
• A tsunami warning system such as that in the Pacific Ocean can
help save lives.
• When the earthquake struck off Sumatra, a monitoring system could
have predicted the possibility of an ongoing tsunami caused by the
quake by measuring underwater sea currents.
• Such a system can then inform the relevant governments in the area
around the Indian Ocean, and they can then warn their people to
evacuate costal.
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Tsunami Warning System
Global Earth Observation System of
Systems
• The GEOSS was proposed by the G-8 in 2003
with the US initiating the process in an effort to
build a global observation system. Currently, the
GEOSS consists of 54 participating contries.
• Hopefully, the system can help in reducing
potential dangers and loss of lives in future.
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Proposed System in the Indian
Ocean
• Headed by the United Nations, a tsunami warning
system will by set up by the middle of 2006, as agreed
upon during the governmental World Conference on
Disaster Reduction in Kobe, Japan, on 20 January 2005.
• In actual fact, seismologists knew almost immediately
about the earthquake off Indonesia which triggered the
tsunami.
• However, there was no way of relaying the information to
people in the region.
• Hence, a warning system will allow a more coordinated
response to an earthquake (such as contact information)
and this includes prediction of tsunami arrival times.
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Future Measures
Government Policies
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References
• library.thinkquest.org
• www.mead.k12.wa.us
• www.science.smith.edu
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