Survivors and families of victims of the Indian Ocean tsunami 20 years ago visited mass graves, lit candles and comforted one another across Southeast and South Asia in ceremonies on Thursday to mark the disaster that killed some 230,000 people. The tsunami on Dec. 26, 2004 was triggered by a 9.1 magnitude quake off the coast of Indonesia’s Aceh province, sending waves as high as 17.4 meters (57 feet) slamming into coastlines of Indonesia, Thailand, Sri Lanka, India and nine other countries.