The incident of South Asia Tsunami 2004---------------------------------------------2
What is “tsunami”? -----------------------------------------------------------------------3
Causes of South Asia Tsunami-----------------------------------------------------------11
Impact of South Asia Tsunami ---------------------------------------------------------15
Measures to alleviate the impact of tsunami------------------------------------------18
The information of the Indonesian Earthquake in 2004
26 December 2004 (Tuesday)
00:58:55(the local time of Jakarta and Bangkok is UTC+7)
Felt by few people onboard small vessels. Not observed on the coast.
Felt by most people onboard small vessels. Observed by few people on the coast.
IV. Largely observed
Felt by all onboard small vessels and by few people onboard large vessels. Observed by most people on the coast.
Few small vessels move slightly onshore.
Felt by all onboard large vessels and observed by all on the coast. Few people are frightened and run to higher ground.
Many small vessels move strongly onshore, few of them crash into each other or overturn. Traces of sand layer are left behind on ground with favourable conditions. Limited flooding of cultivated land.
Limited flooding of outdoor facilities (e.g. gardens) of near-shore structures.
VI. Slightly damaging
Many people are frightened and run to higher ground.
Most small vessels move violently onshore, crash strongly into each other, or overturn.
Damage and flooding in a few wooden structures. Most masonry buildings withstand.
Most people are frightened and try to run to higher ground.
Many small vessels damaged. Few large vessels oscillate violently. Objects of variable size and stability overturn and drift. Sand layer and accumulations of pebbles are left behind. Few aquaculture rafts washed away.
All people escape to higher ground, a few are washed away.
Most of the small vessels are damaged, many are washed away. Few large vessels are moved ashore or crash into each other. Big objects are drifted away. Erosion and littering in the beach. Extensive flooding. Slight damage in tsunami control forest, stop drifts. Many aquaculture rafts washed away, few partially damaged.
Most wooden structures are washed away or demolished. Damage of grade 2 in a few masonry buildings. Most reinforced concrete buildings sustain damage, in a few damage of grade 1 and flooding is observed.
Most large vessels are destroyed or washed away. Many large vessels are moved violently ashore, few are destroyed. Extensive erosion and littering of the beach. Local ground subsidence. Partial destruction in tsunami control forest, stop drifts. Most aquaculture rafts washed away, many partially damaged.
Damage of grade 3 in many masonry buildings, few reinforced concrete buildings suffer from damage grade 2.
X. Very destructive
General panic. Most people are washed away.
Most large vessels are moved violently ashore, many are destroyed or collide with buildings. Small boulders from the sea bottom are moved inland. Cars overturned and drifted. Oil spills, fires start. Extensive ground subsidence.
Damage of grade 4 in many masonry buildings, few reinforced concrete buildings suffer from damage grade 3. Artificial embankments collapse, port water breaks damaged.
Lifelines interrupted. Extensive fires. Water backwash drifts cars and other objects in the sea. Big boulders from sea bottom are moved inland.
Damage of grade 5 in many masonry buildings. Few reinforced concrete buildings suffer from damage grade 4, many suffer from damage grade 3.
XII. Completely devastating
Practically all masonry building demolished. Most reinforced-concrete buildings suffer from at least damage grade 3.
(Adapted from “Papadopoulos, G. A. and Imamura, F. (2001). A proposal for a new tsunami intensity scale”
South Asia Tsunami was caused by the collision of the Indo-Australian Plate and the Eurasian Plate, pushing down the oceanic crust and creating fault fracture at plate boundaries. The fracture extended from south to north and led to an earthquake with 9.1 in magnitude. The enormous energy deformed the seabed, resulting in the upsurge of waves which spread out rapidly in all directions. Tsunami was triggered.
Distribution of plates in South Asian region
Relationship between earthquake and tsunami
The process of tsunami triggered by the Indonesian Earthquake 2004
2. Causes of the disaster
a. Lack of Tsunami Early Warning System
According to Charles McCreery, the director of the National Oceanic and Atmospheric Administration (NOAA) in the U.S.A., the South Asian region lacked a formal set of early warning system. After detecting the earthquake, they immediately informed the navy military of Australia and the United States, the embassies and the state councils of many countries but they could not pass this message to the citizens of South Asia, including India, Thailand and Sri Lanka. These countries did not establish a set of tsunami early warning system to remind their citizens to evacuate to those safe inland regions at that time.
b. Lack of evacuation guidelines and awareness
It’s rare to see huge tsunami in the Indian Ocean. Such tsunami only occurs once every seven hundred years. Thus, local citizens in South Asia were helpless because they lacked such evacuation drilling and awareness.
c. Destruction of ecological environment of coastal areas
Failure of environmental protection strategy indirectly led to this disaster. Owing to overdevelopment, destruction of the ecological environment of the coastal areas in Thailand made it the most severely hit county in this disaster. In order to develop tourism at Phuket, Thailand, mangrove trees at the coastal regions were removed for resort development. Many years ago, the ecological environment of Phi Phi Island was destroyed after the shooting of a movie on the island.
On the contrary, Bangladesh faced a continuous threat of cyclones ten years ago. After that disaster, the country replanted wind-breaks and restored the coastal ecology to enable its coastal areas to be protected by coral reefs and mangrove so as to reduce the loss caused by cyclones.
The major destruction of tsunami includes flooding, damage of coastal structures and erosion. The strong current may cause the collapse of buildings and the erosion of their foundation. The buoyancy and the shear of sea water can move buildings and automobiles. It’s very dangerous for drifting rubbles to hit each other. The retreat of tsunami waves may also erode the coastline.
c. Economic Impact
The tsunami had great impact on the economies of South Asian countries. Sri Lanka and Maldives were the countries most severely hit by the tsunami. Their tourism, fishery and infrastructure all required reconstruction. The government of Sri Lanka articulated that they needed 1.3 billion to repair the destroyed roads, railways and hotels in the east coast. The economy of Sri Lanka had just recovered after 20 years of civil war. The tsunami might pull down its economic growth. Besides, Maldives is the smallest country among these South Asian countries. Although there was no loss of human life, the country suffered heavy blows due to its low topography. Many luxury resorts had to be closed for renovation for months. Since tourism accounts for 50% of foreign exchange earnings of the country, it is estimated that its economic growth would be pulled down.
You may refer to the following website for details: http://news.bbc.co.uk/1/hi/business/4154277.stm
2. Environmental Impact:
You may browse the following website. It has more than 20 satellite photos showing the scenes of different places before and after the Tsunami. Observe the changes in the landscapes.
A. National measures
The tsunami early warning system can help the coastal residents to know the approaching of destructive tsunami and make appropriate preparation and reaction.
1. An effective tsunami early warning system should include the functions of:
identifying tsunami hazard and assessing the risk of the hazard, so as to reduce the impact of tsunami. Tsunami risk assessment maps can also be drawn to show the possible areas of flooding.
issuing timely warnings. For a distant tsunami, real time earthquake and sea level monitoring is important. The data can be used to confirm the occurrence of a destructive tsunami. The information collected can be disseminate immediately to the public. For a local tsunami, there may not be enough time for an official warning. Residents should respond according to their knowledge on tsunami.
continuous and sustained education on knowledge of tsunami. Education is a fundamental path to inform the public and next generations about tsunami. Government support and the development of related laws and regulations are important.
Deep-ocean Assessment and Reporting of Tsunami System
This system uses sea buoys and inductors for assessment. The two-way communication system allows the Tsunami Warning Centre to set up numerous observation stations. Data is collected every 15 seconds and the occurrence of tsunami is analyzed every hour. Deep-ocean Assessment and Reporting of Tsunami System transmits standard data, including the measurement of sea-level every 15 seconds in a 6-hour interval. The two-way communication system includes functions of real-time troubleshooting and diagnosis.
(Not in scale)
Besides, the early warning system should also include the planning of evacuation routes, evacuation drilling and public education related to the hazard.
2. Planting mangrove
The representative of the World Wide Fund pointed out that mangrove and coral reefs can alleviate the impact of tsunami wave. Mangrove is a kind of dense low trees growing at tropical coasts. It has a dense system of roots to bind the soil together and protect the coasts from destructive waves. It was proved that tsunami had less impact on areas with mangrove in 2004. Marriott Hotel in Phuket, Thailand is built in areas of sea turtle hatchery, so it was constructed with strict environmental guidelines. The mangrove swamps were preserved well. The Hotel suffered less in the disaster when compared with other areas or hotels.
B. Individual actions
1. To know about the omen on the approach of tsunami
In coastal areas, tsunami will occur after a few minutes you felt the shocks of a big earthquake. Before the occurrence of tsunami, the sea level will move forward or backward very quickly. In most cases, the approaching tsunami will generate great noise, just like the sound of a moving train or a landing plane. This is especially the case at night.
When you find there are earthquakes or observe the exposure of seabed after the sudden retreat of seawater at beaches or coastal areas, you should:
Move to higher ground immediately.
Stop all water sports.
Small vessels in deep sea should avoid moving to the coasts or shallow water.
Do not surf when there is a tsunami!
Do not return to ports if your vessels are at sea because it is not easy to observe tsunami in big oceans. Tsunami can cause rapid changes in tidal levels and generate unpredictable, dangerous currents at ports and harbours.
If there is time, move your vessels to areas with sea level more than 400 m.
Keep in contact with the harbour management authorities.
Tsunamis generated in distant oceans will generally give people enough time to move to higher ground. For local tsunamis, you may only have a few minutes to move to higher ground when you feel there is ground shaking. Don’t wait for tsunami warning to take action.