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.

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.