Understanding of the Sumatran subduction zone and its hazards has increased since the 2004 Indian Ocean earthquake and tsunami.

The powerful earthquake off the coast of the Indonesian island of Sumatra on Dec. 26, 2004, triggered a tsunami that impacted a dozen countries, reaching as far as East Africa.

On Dec. 26, 2004, an earthquake-triggered tsunami raced across the Indian Ocean with 40-foot-high waves slamming into India, Thailand, Indonesia and several other countries, killing at least 225,000 people and leaving thousands injured.