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.

Understanding of the Sumatran subduction zone and its hazards has increased since the 2004 Indian Ocean earthquake and tsunami.

Survivors and families of victims visited mass graves, lit candles and comforted one another across Southeast and South Asia in ceremonies to mark the disaster that killed some 230,000 people.

At one in Ulee Lheue village, where 14,000 unidentified victims are buried, families of those killed by the tsunami wept and placed flowers. There were similar memorial ceremonies in Ban Nam Khem, a small fishing town in Thailand that was among those most devastated by the tsunami in the country,

People started gathering in prayer today and visiting mass graves in Aceh, one of the worst-hit areas by the Boxing Day Indian Ocean tsunami which killed an estimated 230,000 people across a dozen countries.