Indian Ocean Earthquake of 2004

The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia.

The quake itself is known by the scientific community as the Sumatra-Andaman earthquake. The resulting tsunami is given various names, including the 2004 Indian Ocean tsunami, Asian Tsunami, Indonesian Tsunami, and Boxing Day Tsunami.

The earthquake was caused by subduction and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 meters (100 feet) high. It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest hit, followed by Sri Lanka, India, and Thailand.

"Normally, a small earthquake might last less than a second; a moderate sized earthquake might last a few seconds. This earthquake lasted between 500 and 600 seconds," said Charles Ammon, associate professor of geosciences at Penn State University.

The quake released an amount of energy equal to a 100 gigaton bomb, according to Roger Bilham, professor of geological sciences at the University of Colorado.

And that power lasted longer than any quake ever recorded.

The earthquake that created the devastating Asian tsunami on 26 December 2004 was three times more powerful than first thought, say researchers analysing long-period seismic waves.

The finding could upgrade the quake to the second strongest ever recorded and explain why the tsunami caused such great damage across the ocean in Sri Lanka and India.

Earthquakes are classified on the Richter scale by their largest-amplitude seismic wave. These seismic waves come in a variety of periods, or wavelengths - but only the most powerful quakes pack a lot of energy into long-period waves.

The earthquake that generated the great Indian Ocean tsunami of 2004 is estimated to have released the energy of 23,000 Hiroshima-type atomic bombs, according to the U.S. Geological Survey (USGS).

Giant forces that had been building up deep in the Earth for hundreds of years were released suddenly on December 26, shaking the ground violently and unleashing a series of killer waves that sped across the Indian Ocean at the speed of a jet airliner.