tushami

JNANA PRABODHINIJNANA PRABODHINI

Tsunami: Tsunami: Magnitude of TerrorMagnitude of Terror

CausesCauses


ContentsContents

• Plate Tectonics

• Tsunami Formation

• Indian Ocean Earthquake


CausesCauses

Plate TectonicsPlate 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.


Plates of The WorldPlates of The World



• 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.


CausesCauses

Tsunami FormationTsunami Formation



• DefinitionTsunamis 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.


Tsunami FormationTsunami 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.



• 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.



• 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.



• As a tsunami reaches the shore, it begins to lose energy whereby part of its wave energy is reflected offshore, while the shoreward-propagating wave energy is dissipated through friction and turbulence.

• In spite of this, tsunamis still reach the coast with tremendous amounts of energy


CausesCauses

Indian Ocean EarthquakeIndian Ocean Earthquake


Indian Ocean EarthquakeIndian Ocean Earthquake

Statistics

• Date : 26 December 2004Origin Time : 00:58 53 s UTCLatitude/Longitude : 3.267° North / 95.821° EastDepth : 10 kmMagnitude : 9.0Locality : 255 km SSE of Banda Aceh, Northern Sumatra


Official ReportOfficial 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.


ComparisonComparison

• 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.

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)


Tsunami:Tsunami:Magnitude of TerrorMagnitude of Terror

EffectsEffects


ContentsContents

• Damage to Countries

• Death Toll

• Economy

• Environment


EffectsEffects

DAMAGE TO COUNTRIESDAMAGE TO COUNTRIES


IndonesiaIndonesia

• 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.


IndonesiaIndonesia

• 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.


Sri Lanka 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.


Sri LankaSri 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.


India India

• 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.


IndiaIndia

• 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.


EffectsEffects

Death Toll Death Toll



Country wheredeaths

occurred

Deaths

Injured Missing DisplacedConfirmed Estimated1

Indonesia 173,981 220,000~100,00

06,245

400,000- 700,000

Sri Lanka 38,195 38,195 15,68623,000+

2 ~573,000

India 10,744 16,413 - 5,669 380,000

Thailand 5,305 3 11,000 8,457 4,499 -

Somalia 150+ 298 - - 5,000

Myanmar (Burma)

59 2,500 45 7,000 4 3,200

Malaysia 68 – 74 74 299 - -

Maldives 82 108 - 2612,000 –

22,000



Seychelles 1 – 3 3 - - -

Tanzania 10 10+ - - -

Bangladesh 2 2 - - -

South Africa 2 5 2 - - -

Kenya 1 2 2 - -

Yemen 1 1 - - -

Madagascar - - - - 1,000+

Total 228,601+ ~288,608 ~125,000 ~40,000 ~1.5 million

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).


EffectsEffects

Economical Impact Economical Impact


Economical Impact 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).


Undesirable Effects 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.



• 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.


Undesirable EffectsUndesirable 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.



• Tropical rainstorms in Aceh province of Indonesia and flooding along Sri Lanka's low-lying 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.



• 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.



• 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.



• 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.


EffectsEffects

Environmental Consequences Environmental Consequences


Environmental Consequences 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.


Tsunami: Tsunami: Magnitude of TerrorMagnitude of Terror

Relief Efforts Relief Efforts


ContentsContents

• Emergency Relief

• Rehabilitation

• Reconstruction



Emergency ReliefEmergency Relief


Search and Rescue 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.

• 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.

• 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.


Identification of bodiesIdentification of bodies

Searching for missing loved ones Searching for missing loved ones

Medical Aid Medical Aid

Provision of Food & Drinking WaterProvision of Food & Drinking Water Housing Housing Education Education



RehabilitationRehabilitation


Volunteer WorkVolunteer 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.


Relief EffortsRelief Efforts

Reconstruction Reconstruction


TourismTourism Fishing Industry Fishing Industry

Agriculture Agriculture Donations Donations


Tsunami:Tsunami:Magnitude of TerrorMagnitude of Terror

Future MeasuresFuture Measures


ContentsContents

• Tsunami Warning System

• Government Policies

• Suggested Precautions



Tsunami Warning SystemTsunami Warning System



DefinitionA 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.



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.


Proposed System in the Indian Proposed System in the Indian OceanOcean

• 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.



Government PoliciesGovernment Policies


ReferencesReferences

• library.thinkquest.org

• www.mead.k12.wa.us

• www.science.smith.edu

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