A colossal earthquake begins to shake the northern part of Sumatra and the Andaman Sea to its north. Seven minutes later a stretch of the Indonesian subduction zone 1200 kilometers long had slipped by an average distance of 15 meters. A large tsunami triggered by the earthquake spread outward from off the Sumatran coast. The worst part of it washed away whole cities in Indonesia, but every country on the shore of the Indian Ocean was also affected. In Indonesia, some 240,000 people died from the quake and tsunami combined. About 47,000 more people died, from Thailand to Tanzania, when the tsunami struck without warning.