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.

Thursday marks the 20 th anniversary of the 2004 Indian Ocean tsunami, one of the deadliest natural disasters in modern history. The Boxing Day quake was one of the largest ever recorded. “This earthquake didn’t just break all the records, it also brok ...