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

Christmas in 2004, a 9.1 magnitude earthquake under the Indian Ocean triggered tsunami waves that killed some 230,000 people across a dozen countries.

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.