December 26, 2004December 26, 2004

Sumatra Earthquake Sumatra Earthquake

& Indian Ocean & Indian Ocean TsunamiTsunami

Tsunami 101Tsunami 101

How a Tsunami WorksHow a Tsunami Works

• A tsunami may be less than a foot in height A tsunami may be less than a foot in height on the surface of the open ocean, which is on the surface of the open ocean, which is why they are not noticed by sailors. why they are not noticed by sailors.

• But the powerful shock wave of energy But the powerful shock wave of energy travels rapidly through the ocean as fast as travels rapidly through the ocean as fast as a commercial jet. a commercial jet.

• Once a tsunami reaches shallow water near Once a tsunami reaches shallow water near the coast it is slowed down. the coast it is slowed down.

• The top of the wave moves faster than the The top of the wave moves faster than the bottom, causing the sea to rise dramatically.bottom, causing the sea to rise dramatically.

Indian Ocean TsunamiIndian Ocean TsunamiWave Propagation in HoursWave Propagation in Hours

Indian Ocean Indian Ocean TsunamiTsunamiDecember 26, 2004December 26, 2004

Tsunami BackgroundTsunami Background

• A tsunami is not a single wave but a series A tsunami is not a single wave but a series of waves, also known as a wave train. The of waves, also known as a wave train. The first wave in a tsunami is not necessarily the first wave in a tsunami is not necessarily the most destructive.most destructive.

• • Tsunami waves can be very long (as much Tsunami waves can be very long (as much as 60 miles) and be as far as one hour as 60 miles) and be as far as one hour apart. They are able to cross entire oceans apart. They are able to cross entire oceans without great loss of energy. The Indian without great loss of energy. The Indian Ocean tsunami traveled as much as 3,000 Ocean tsunami traveled as much as 3,000 miles to Africa, arriving with sufficient force miles to Africa, arriving with sufficient force to kill people and destroy property. to kill people and destroy property.

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Tsunami FactsTsunami Facts

• The 2004 Sumatra tsunami killed over 123,000 The 2004 Sumatra tsunami killed over 123,000 people.people.

• The most damaging tsunami on record before The most damaging tsunami on record before 2004 was the one that killed an estimated 2004 was the one that killed an estimated 40,000 people in 1782 following an 40,000 people in 1782 following an earthquake in the South China Sea. earthquake in the South China Sea.

• In 1883 some 36,500 people were killed by In 1883 some 36,500 people were killed by tsunamis in the South Java Sea, following the tsunamis in the South Java Sea, following the eruption of Indonesia's Krakatoa volcano. In eruption of Indonesia's Krakatoa volcano. In northern Chile more than 25,000 people were northern Chile more than 25,000 people were killed by a tsunami in 1868. killed by a tsunami in 1868.

Tsunami DangersTsunami Dangers

• Many people were killed by the Indian Ocean Many people were killed by the Indian Ocean tsunami because they went down to the beach to tsunami because they went down to the beach to view the retreating ocean exposing the seafloor. view the retreating ocean exposing the seafloor.

• Apparently they were unaware that this Apparently they were unaware that this phenomenon precedes a killer wave. Experts phenomenon precedes a killer wave. Experts believe that a receding ocean may give people as believe that a receding ocean may give people as much as five minutes' warning to evacuate the area. much as five minutes' warning to evacuate the area.

• • Because tsunamis can approach the shore as fast as Because tsunamis can approach the shore as fast as 100 miles per hour it is often too late to get away if 100 miles per hour it is often too late to get away if you see one. An approaching tsunami is not you see one. An approaching tsunami is not something to be admired unless you are safely on something to be admired unless you are safely on high ground. high ground.

Tsunami DangersTsunami Dangers

• Remember that a tsunami is a series Remember that a tsunami is a series of waves and that the first wave may of waves and that the first wave may not be the most dangerous. not be the most dangerous.

• The danger from a tsunami can last The danger from a tsunami can last for several hours after the arrival of for several hours after the arrival of the first wave. the first wave.

• A tsunami wave train may come as a A tsunami wave train may come as a series of surges that are five minutes series of surges that are five minutes to an hour apart. to an hour apart.

Banda Aceh, capital city of Banda Aceh, capital city of SumatraSumatra

IRS-P6 AWiFS Image of 21-Dec-04 IRS-P6 AWiFS Image of 26-Dec-04

A Close View of Trinkat IslandTsunami - 2004

Pre-Event Post-Event

Works CitedWorks Cited

• BBCBBC

• National GeographicNational Geographic

• Oceansonline.comOceansonline.com

• Office of Naval ResearchOffice of Naval Research

• ReutersReuters

• USGSUSGS

• WikipediaWikipedia