Southeast Asian countries are marking the fifth anniversary of the Indian Ocean tsunami that killed more than 220,000 people from Indonesia to Sri Lanka. In Indonesia's Aceh province, which lost almost 170,000 people, a day of prayers and remembrance marked one of the world's worst natural disasters. Memorial services are also underway in Thailand where more than 50,000 people were killed as the wall of water smashed into coastal communities. The 2004 tsunami was triggered by a 9.3-magnitude earthquake off the coast of Sumatra. Seismologists say a similar disaster is almost certain to strike the region again. Experts warn that many countries remain ill-prepared.
