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Occurrences of Tsunamis in the Indian Ocean

• Map of historical occurrences of Tsunamis in the Indian Ocean
• The catastrophe of 26 December 2004 in the Indian Ocean
• Results of the missing communication infrastructure
• Early warning systems in the Indian Ocean
• The greatest known Tsunamis in the Indian Ocean

Map of historical occurrences of Tsunamis in the Indian Ocean

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The catastrophe of 26 December 2004 in the Indian Ocean

The quake off Sumatra on 26 December 2006 caused a disastrous tsunami that flooded about 10 000 kilometres of coastal regions in the Indian Ocean and caused the loss of 280 000 lives. The sea subsoil off Sumatra had abruptly raised itself up to ten meters within a very short period of time along a distance of about 1 200 kilometres. The movement of the Indian-Australian plate, which moves by six to seven centimeters towards the north-east every year, caused this. The enormous tension energy that developed during this movement was released during this quake. It reached 9,3 on the Richter scale – one of the strongest quakes ever measured.

Results of the missing communication infrastructure

Experts have been critical of the fact that there had not been a tsunami warning system in the Indian Ocean like in the Pacific Ocean. According to their information, several thousand lives could have been saved if such a warning system had been in place. The fact that the Pacific tsunami warning system on Hawaii had already predicted a flood wave just minutes after the quake helped nobody. In the affected countries, there were neither contact persons nor communication infrastructures. In addition, warning reports from Thailand were not forwarded to the authorities for fear of impacting on the tourism industry so that many people had little chance of escaping.

Early warning systems in the Indian Ocean

Since November 2005 the tsunami early warning system developed under German participation – Tsunami Early Warning System (TEWS) - was installed in the geologically critical zone of the Indian Ocean, the Sunda Arc which is a geologically active 3 000-kilometre-long curve where the Australia Plate sinks beneath the Eurasia Plate. The TEWS should in future contribute substantially towards the protection of the region from natural disasters like tsunamis. In addition to other organisations and bodies, quake research findings from the Geo Research Centre (GFZ) in Potsdam were used in the development of the system.

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The greatest Tsunami catastrophes worldwide – an overview

Source: National Geophysical Data Center - Tsunami Event Database

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The greatest known Tsunamis in the Indian Ocean

17. July 2006: A Tsunami was evoked by a quake south of Java, Indonesia. No warning by the Indonesian government was disseminated and 700 people died. The A3M Tsunami Alarm System had successfully warned its users, no casualties happened.

26 December 2004: The worst tsunami disaster in living history was caused by an earthquake in the Indian Ocean off the island of Sumatra measuring 9,3 on the Richter Scale. More than 300 000 people (many of them European holidaymakers) were killed in eight Asiatic countries (in particular Indonesia/Sumatra, Sri Lanka, India, Thailand, Myanmar, Maldives, Malaysia and Bangladesh). The flood wave even reached coastlines several thousand kilometres away, like East and Southeast Africa. There were also casualties in Somalia, Tanzania, Kenya, Madagascar and the Seychelles.

27. August 1883: One of the greatest volcanic eruptions ever happened on the island of Krakatau in Indonesia. The eruption destroyed almost two thirds of the island and caused flood waves of 40 meters high, killing 36 000 people.
Even on the coast of Great Britain the tsunami was noticeable through a half-a-meter rise of the sea level. The air pressure wave from the blast travelled around the earth seven times.

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Read more about:
- Occurrences of Tsunamis Worldwide
- Occurrences of Tsunamis in the Pacific Ocean
- Occurrences of Tsunamis in the Atlantic Ocean
- Occurrences of Tsunamis in the Mediterranean

Sources, follow-up links:
Information about terms, causes, characteristics, occurences, prevention and list of past tsunamis (www.en.wikipedia.org)
Archives of tsunamis photographs (www.tsunami.org)
Details of the largest historical tsunamis (www.teachervision.fen.com) http://www.visibleearth.nasa.gov/

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