What's changed 20 years after the Indian Ocean tsunami?

On December 26, 2004, a 9.1-magnitude earthquake triggered a devastating tsunami in the Indian Ocean. Over 227,000 lives were lost across 15 countries and there were millions of dollars in material damages. This was one of the worst natural disasters of the 21st century. But 20 years on, what have we learned from it? In this gallery, we look back at the Indian Ocean tsunami to remember what was done and what the future of tsunami prevention looks like. Click on.

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Underwater earthquake -

On December 26, 2004, a devastating tsunami formed in the Indian Ocean after a rupture along the fault between the Indian and the Burma plate triggered the Sumatra-Andaman earthquake.

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Huge waves -

The 9.1-magnitude earthquake triggered waves more than 30 meters (100 feet) high.

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A powerful event -

The energy released was the equivalent to 23,000 atomic bombs, similar to that which was dropped on Hiroshima.

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The waves traveled fast -

The tsunami’s waves traveled across the ocean at the speed of 500 mph (804.6 km/h), which is about as fast as a jet plane.

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The waves hit the coast -

The epicenter was located 150 miles (80.4 km) off Sumatra's coast. The north of the island was the most affected. In total, the death toll in Indonesia reached a devastating 165,708.

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It spread across the Indian Ocean -

Hours later, Sri Lanka, India, and Thailand were also hit by it, killing thousands more. The Maldives, Somalia, Malaysia, and Myanmar, among other countries, were also affected by the tsunami.

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Devastation -

In addition to the thousands of people dead, more than 1.5 million people were displaced after the disaster. The material loss came in at around 10 million dollars.

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20 years on -

As we approach two decades since the devastating disaster, what has changed? Let’s take a look.

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Tsunami warning systems -

At the time, there were a number of international and regional tsunami warning systems, but these have evolved in terms of both detection and preparedness.

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Global Tsunami Warning System -

The Global Tsunami Warning System spans across all regions, including the Pacific, North-East Atlantic, Indian Ocean, Mediterranean, and Caribbean.

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Global Tsunami Warning System -

When a sea level disturbance is detected, an alert is immediately issued to coastal communities as a preventative measure.

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Tsunami Ready Programme -

These alerts are indeed helpful and can save lives, but people need to know what to do and have an action plan in place. This is why in 2015 the Tsunami Ready Recognition Programme was created.

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Tsunami Ready Programme -

The program uses 12 indicators to recognize the level of tsunami preparedness in communities. These include performing evacuation drills and mapping risk areas. Today, over 30 countries are deemed “tsunami ready.”

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Tsunami Ready Programme -

“Our focus has been on providing not just alerts but a comprehensive preparedness strategy—through real-time monitoring, community education, and strengthened coastal defenses. We now know within minutes if a tsunami is imminent, and communities have the tools to act. This progress has been lifesaving,” said Bernardo Aliaga, Head of Tsunami Resilience at UNESCO.

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Tools -

Several tools have been developed to help detect tsunamis. One example is the Deep-ocean Assessment and Reporting of Tsunami (DART) buoys, which track tsunami waves in real time.

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Tsunami relief -

The governments of all affected nations spent millions in aid to rebuild what was lost in the tsunami. International relief was also key in the process.

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Tsunami relief -

The government of Indonesia, for instance, created a Master Plan for the Rehabilitation and Reconstruction of Aceh and Nias, North Sumatra.

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Tsunami relief -

EU-funded and United Nations relief operations also helped the victims of the tsunami. It included access to safe water and sanitation, health services, shelter, as well as psychosocial support.

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Aid -

International aid was key in the response to the Indian Ocean tsunami. Global Christian humanitarian organization World Vision, for instance, raised more than $350 million.

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World Vision -

The organization claims to have “offered training and employment opportunities to 40,000 people, conducted child-rights awareness sessions for more than 27,000 people, and extended educational support to over 2,000 teachers and 137,000 children.”

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World Vision -

According to their website, the funds also allowed for 12,000 homes to be built. Other achievements include the building of 84 schools, 60 playgrounds, and 27 health clinics.

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Rebuilding -

Banda Aceh was the most affected city by the tsunami. Around 100,000 houses were rebuilt after the disaster.

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20 years on: remembering the disaster -

The 20th anniversary of the Indian Ocean tsunami will be marked by a number of memorials and religious ceremonies across the affected regions.

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20 years on: Sri Lanka -

In Sri Lanka, a rebuilt express train which was hit by the tsunami will ride from Colombo to the same spot at Peraliya where the giant waves hit it. More than 35,000 people died in the country in 2004.

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20 years on: Thailand -

In Thailand, a government memorial ceremony will take place on December 26. More than 5,000 people were killed by the tsunami in the country.

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20 years on: Thailand -

A tsunami exhibition, a documentary screening, and talks by government and UN bodies on tsunami preparedness will also be held in a hotel in Phang Nga province.

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20 years on: Thailand -

Another event includes a "walk-run" which will take place on December 27 at the Ban Nam Khem Tsunami Memorial Park.

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Museum Tsunami Aceh -

The Aceh Tsunami Museum, located on Jalan Iskandar Muda Street, in Banda Aceh, is a reminder of the impact of the tsunami in Indonesia.

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Tsunami Victims Cemetery -

The Tsunami Victims Cemetery is the final resting place for many unidentified victims of the Indian Ocean Tsunami. It’s located in Khao Lak district, Phang Nga province of southern Thailand.