From the Field

2004 Indian Ocean earthquake and tsunami: Facts, FAQs, and how to help

A powerful undersea earthquake that struck off the coast of Sumatra island, Indonesia, set off the 2004 Indian Ocean tsunami, also known as the Christmas or Boxing Day tsunami, on Sunday morning, Dec. 26, 2004. The magnitude 9.1 quake ruptured a 900-mile stretch of fault line where the Indian and Australian tectonic plates meet. It was a powerful megathrust quake, occurring where a heavy ocean plate slips under a lighter continental plate.

The quake caused the ocean floor to suddenly rise by as much as 40 meters, triggering a massive tsunami. Within 20 minutes of the earthquake, the first of several 100-foot waves hit the shoreline of Banda Aceh, killing more than 100,000 people and pounding the city into rubble. Then, in succession, tsunami waves rolled over coastlines in Thailand, India, and Sri Lanka, killing tens of thousands more. Eight hours later and 5,000 miles from its Asian epicenter, the tsunami claimed its final casualties on the coast of South Africa. In all, nearly 230,000 people were killed, making it one of the deadliest disasters in modern history.

Since the 2004 tsunami, governments and aid groups have prioritized disaster risk reduction and preparedness. Only three weeks after the tsunami, representatives of 168 nations agreed to the Hyogo Framework for Action, which paved the way for global cooperation for disaster risk reduction. Since then, ocean floor earthquake sensors have been installed to trigger early warnings, and many local communities have been trained in evacuation and disaster response.

Major earthquakes and tsunamis in August and September 2018 have tested Indonesia’s ability to respond and recover. Then, in December 2018, Anak Krakatau volcano’s ongoing eruptions in the Sunda Strait caused undersea landslides that triggered a tsunami that struck beaches in both Sumatra and Java. With no warning triggered by the volcanic activity, more than 400 people died. Now, the Indonesian government is working to add volcano sensors to its warning systems.

When disaster strikes, World Vision is there. Help us respond to disasters like earthquakes and tsunamis.

FAQs: What you need to know about the 2004 Indian Ocean tsunami

Explore facts and frequently asked questions about the 2004 Indian Ocean earthquake and tsunami, and learn how you can help survivors of disasters.

Fast facts: 2004 Indian Ocean earthquake and tsunami

  • The Sumatra-Andaman earthquake, which caused the 2004 Indian Ocean tsunami, is estimated to have released energy equivalent to 23,000 Hiroshima-type atomic bombs.
  • In Banda Aceh, the landmass closest to the quake’s epicenter, tsunami waves topped 100 feet.
  • The tsunami’s waves traveled across the Indian Ocean at 500 mph, the speed of a jet plane.
  • The 2004 Indonesia earthquake caused a shift in the Earth’s mass that changed the planet’s rotation.
  • Total material losses from the tsunami were estimated at $10 million.


How many people died in the 2004 Indian Ocean earthquake and tsunami?

Nearly 230,000 people died in the 2004 Indian Ocean earthquake and tsunami, making it one of the deadliest disasters in modern history.


Why was the 2004 Indian Ocean tsunami so destructive and deadly?

The first giant waves from the Indian Ocean tsunami reached Banda Aceh, a city of about 300,000 people within 15 or 20 minutes after the earthquake. Few residents of the densely populated area realized that the earthquake they had felt could cause a tsunami, and there was little time to flee to higher ground.

Traveling as fast as 500 mph, the waves spread out to distant countries including Thailand, Sri Lanka, and India. With no warning, coastal populations were caught by the pounding waves. Many families that made their living fishing lost everything; whole communities were wiped out by the tsunami.


Map of the 2004 Indian Ocean tsunami that killed nearly 230,000 people was one of the deadliest disasters in modern history. It was caused by a magnitude-9.1 earthquake where the Indian and Australian tectonic plates meet.
©2005 image courtesy of the U.S. Geological Survey

Where did the earthquake hit?

The Sumatra-Andaman earthquake struck 150 miles from the coast of Sumatra island, on the northwest of the Indonesian island group, and 31 miles below the ocean floor. The quake occurred along a fault line between the Indian tectonic plate and the Burma microplate, part of the Australian plate. The Indian plate is a heavy ocean plate, and it slipped under the lighter coastal plate, rupturing a 900-mile length of the fault.

Indonesia lies between the Pacific Ring of Fire, where 90% of earthquakes occur, and the second-most active seismic zone, the Alpide belt.


How big was the earthquake that caused the Indian Ocean tsunami?

The earthquake’s magnitude was measured between 9.1 and 9.3, making it the third-most powerful quake since 1900. Magnitude is a measure of the release of energy at the earthquake’s source.

In the worst-affected areas, the quake’s intensity rated IX on the Mercalli scale, the second highest rating possible. So the quake caused violent shaking and extensive damage to even well-built buildings. Earthquake intensity is based on observation and varies in different places.


How can I help people affected by earthquakes and tsunamis?

  • Give: Donate to World Vision’s disaster relief fund to bring help when another disaster strikes.
  • Pray: Join us in praying for families as they recover and rebuild after earthquakes and other disasters:  Almighty Father, we ask for Your caring mercy on people hard hit by natural disasters, including earthquakes and tsunamis. In the midst of their struggle to recover, give them patience, peace, and hope that their lives will continue to improve.


How did World Vision help people recover from the 2004 Indian Ocean earthquake and tsunami?

In response to the 2004 Indian Ocean earthquake and tsunami, World Vision mounted its largest-ever relief response across five countries simultaneously — Indonesia, Sri Lanka, Thailand, India, and Myanmar — and raised more than $350 million.

World Vision focused on the needs of children, families, and their communities, with programs to provide protection, healthcare, education, and livelihoods. We provided training and employment opportunities to 40,000 people, child-rights awareness sessions for more than 27,000 people, educational support for more than 2,000 teachers and 137,000 children, and implemented community-level disaster risk reduction programs.

World Vision built 12,000 homes, 200 Child-Friendly Spaces, 84 schools, 60 playgrounds, and 27 health clinics. We built roads, bridges, farms, factories, marketplaces, boat-building centers, and restored a fishing harbor. Our coastal restoration programs included planting 56,000 mangroves to serve as a natural barrier to rising ocean levels.

Most tsunami-related rehabilitation work was completed by 2007. Today, World Vision’s expansive child sponsorship, health, education, water, food, agriculture, and income-generating activities are found across each of the tsunami-affected countries.


How does World Vision help people prepare for disasters?

World Vision pre-positions relief supplies and trains staff for emergency work in areas like child protection, relief supply chain management, clean water provision, and more. In disaster-prone communities where we work, we organize programs to reduce risks from disasters and train local first responders.

In nearly 100 countries around the world, World Vision works to improve the lives of children and families and to help them prepare for and recover from disasters.


2004 Indian Ocean earthquake and tsunami timeline

December 26, 2004

  • 7:58 a.m.: A magnitude 9.1 earthquake occurs off the northwest coast of Sumatra.
  • +15 minutes: The Pacific Tsunami Warning Center in Hawaii registers the quake.
  • +20 to 30 minutes: Tsunami waves more than 100 feet high pound the Banda Aceh coast, killing about 170,000 people and destroying buildings and infrastructure.
  • +1.5 hours: Beaches in southern Thailand are hit by the tsunami. Among the 5,400 who died were 2,000 foreign tourists.
  • +2 hours: The tsunami strikes the Sri Lankan coastline from the northeast and all around the southern tip; more than 30,000 people are dead or missing. The east coast of India is hard hit from Chennai south; more than 16,000 people are killed.
  • +8 hours: The tsunami reaches the east coast of Africa, killing more than 300 people in Somalia, Tanzania, and Kenya.


Learn more about earthquakes and tsunamis, which are among the most damaging and deadly disasters.

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