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21st Century Tsunami

The causes and features of tsunami and two recent devastating tsunami.

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21st Century Tsunami

Why should you pay attention in school?

Tilly Smith, an 11-year old English schoolgirl, was vacationing with her family in Phuket, Thailand on December 26, 2004. Walking along the beach Tilly noticed that the bubbling sea in Phuket resembled a video taken just before a tsunami in Hawaii in 1946. She'd seen the video in geography class two weeks earlier and insisted to her parents that a tsunami was coming. Her warning saved the approximately 100 tourists and others who were on that beach.

Boxing Day Tsunami 2004

Not everyone had the same warning the people on Tilly's beach had. The Boxing Day Tsunami of December 26, 2004 was by far the deadliest of all time (Figure below). The tsunami was caused by the 2004 Indian Ocean Earthquake. With a magnitude of 9.2, it was the second largest earthquake ever recorded.

The extreme movement of the crust displaced trillions of tons of water along the entire length of the rupture. Several tsunami waves were created with about 30 minutes between the peaks of each one. The waves that struck nearby Sumatra 15 minutes after the quake reached more than 10 meters (33 feet) in height. The size of the waves decreased with distance from the earthquake and were about 4 meters (13 feet) high in Somalia.

Map of the area hit by the Boxing Day Tsunami

The countries that were most affected by the 2004 Boxing Day tsunami.

The tsunami did so much damage because it traveled throughout the Indian Ocean. About 230,000 people died in eight countries. There were fatalities even as far away as South Africa, nearly 8,000 kilometers (5,000 miles) from the earthquake epicenter. More than 1.2 million people lost their homes and many more lost their ways of making a living.

Japan Tsunami 2011

The Japanese received a one-two punch in March 2011. The 2011 Tōhoku earthquake offshore was a magnitude 9.0 and damage from the quake was extensive. People didn't have time to recover before massive tsunami waves hit the island nation. As seen in Figure below, waves in some regions topped 9 meters (27 feet).

Peak tsunami heights from the 2011 tsunami

This map shows the peak tsunami wave heights.

The tsunami did much more damage than the massive earthquake (Figure below).

Damage caused by the 2011 earthquake and tsunami

An aerial view shows the damage to Sendai, Japan caused by the earthquake and tsunami. The black smoke is coming from an oil refinery, which was set on fire by the earthquake. The tsunami prevented efforts to extinguish the fire until several days after the earthquake.

Worst was the damage done to nuclear power plants along the northeastern coast. Eleven reactors were automatically shut down. Power and backup power were lost at the Fukushima plant, leading to equipment failures, meltdowns, and the release of radioactive materials. Control and cleanup of the disabled plants will go on for many years.

Tsunami Warning Systems

As a result of the 2004 tsunami, an Indian Ocean warning system was put into operation in June 2006. Prior to 2004, no one had thought a large tsunami was possible in the Indian Ocean.

Picture of a tsunami warning sign

A sign in Thailand shows an evacuation route.

In comparison, a warning system has been in effect around the Pacific Ocean for more than 50 years. The system was used to warn of possible tsunami waves after the Tōhoku earthquake, but most were too close to the quake to get to high ground in time. Further away, people were evacuated along many Pacific coastlines, but the waves were not that large.


  • The Boxing Day Tsunami of 2004 came from a massive earthquake and traveled across the Indian Ocean, causing death and destruction in 12 nations.
  • In Japan, the tsunami struck very quickly after the 9.0 earthquake in the subduction zone offshore. Many more people died from the tsunami than the quake.
  • Tsunami warning systems are important but are not useful in locations that are very close to the earthquake that generated them.


  1. How does an earthquake generate a tsunami?
  2. Why did so many people die in the Indian Ocean tsunami?
  3. Why do you think there was more damage from the tsunami in Japan than from the earthquake that caused it?

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Use this resource to answer the questions that follow.

  1. What was the magnitude of the Japan Tsunami?
  2. How tall was the world's deepest and largest sea wall?
  3. How many people died or were missing?
  4. How does a tsunami move in deep water?
  5. How far inland did some waves reach?
  6. How fast were the waves moving on land?

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