Tsunamis are caused by disturbances to the earth’s surface such as earthquakes and volcanoes. When a severe disturbance occurs on the ocean floor or on a coastline, it is capable of displacing the water which causes a giant wave.
Cause of the 2004 Asian Tsunami
An earthquake with the magnitude of 9.3 occurred on the ocean floor near the west coast of Sumatra, Indonesia. Known as the Indian Ocean earthquake or the Great Sumatra-Andaman earthquake, it lasted almost 10 minutes. This is the longest duration ever recorded for an earthquake.
This is the second strongest earthquake recorded in history. The strongest earthquake recorded was 9.5 in Valdivia Chile on May 1960 and the third strongest earthquake was the 9.1 that struck Alaska on Good Friday 1964.
The earthquake was located in a subduction zone where the India Plate slides under the Burma Plate. Approximately 1000 miles of sea bed was ruptured which, to date, is the longest rupture ever caused by an earthquake.
Many aftershocks were recorded in the original epicenter as well as off the Nicobar Islands and the Andaman Islands. These continued for several days. Some of the aftershocks were not small, one had a magnitude of 8.7 and some scientists believe this particular aftershock should be considered a “triggered earthquake”.
The Path of the 2004 Asian Tsunami
The rupture caused by the earthquake was in a north-south direction so the strongest part of the tsunami traveled in an east-west direction. In addition, the northern part of the rupture zone had slower action during the earthquake, thus causing lesser wave action in the north.
- The tsunami struck the northern part of Sumatra in Indonesia approximately 15 minutes after the earthquake occurred.
- Thailand was hit within 2 hours even though it was closer to the epicenter but the tsunami seemed to slow down in the Andaman Sea.
- It took 90 minutes to 2 hours to reach the coast of India and the island of Sri Lanka.
- Somalia was struck 7 hours later.
- The tsunami reached the southern tip of Africa 19 hours after the earthquake.
Death Toll Resulting from the 2004 Asian Tsunami
According to the United Nations, there were 229,866 people lost, dead or missing.
There were a large number of foreign tourists visiting the area during the Christmas and it is believed that Sweden suffered the greatest death toll.
- Indonesia suffered the biggest loss with almost 130,700 deaths, 37,000 missing and over 500,000 people displaced.
- Sri Lanka was second with 35,300 deaths and 515,100 people displaced.
- India was third with 12,400 deaths, 5,640 people missing and 647,500 displaced.
- Thailand was fourth with 5,400 people dead, 8,450 people injured, 2,800 missing and 7000 people displaced.
- Somalia reported 78 people dead and 5,000 people displaced.
- Myanmar (Burma) had an unconfirmed death toll of 61 people, 45 injured, 200 missing and 3,200 displaced.
- Maldives had 82 deaths, 26 people missing and over 15,000 people displaced.
- Malaysia had a death count of 68, 299 injured and 6 missing.
- Bangladesh reported 2 people dead and same with South Africa and Yemen. Kenya reported 1 death and 2 injuries.
- Madagascar reported no deaths, injuries or missing persons but over 1,000 people were displaced.
Could There Have Been Less Damage and Death From the 2004 Asian Tsunami?
- There was no tsunami warning system set up in the Indian Ocean and this disaster has now prompted the installation of a warning system. People were totally caught off guard.
- Some countries have destroyed coral reefs in order to allow shipping traffic or fish farming and this reduced the natural barrier that reefs can provide.
- Mangrove trees have been cut down on shorelines in order to build hotels and houses. These trees could have helped reduce the impact of tsunamis.
- Sand dunes have been removed in order to create flat beaches and easy access to the water but these are natural barriers.
- Engineers are designing structures that give less resistance to the force of water, rather than being obstacles.
Sources:
- BBC News
- Emergency Management Australia
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