The death toll continues to rise as rescue teams reach more remote coastal communities in India, Sri Lanka, Thailand, Maldives and Indonesia.
Across the region, emergency services arescramblingto rescue the injured, and provide survivors with tents, blankets, food and clean drinking water.
Indonesian presidential spokesman Andi Mallararengeng says damaged communications are making it difficult to assess the full situation.
"So, we are waiting for more accurate information," he said.
The quake hit Sunday morning, more than 100 kilometers off Indonesia's Sumatra Island.
U.S. experts say it is the worst quake in Indonesian history.
It sent huge tidal waves more than 1,500 kilometers across the Indian Ocean, which caused most of the damage and fatalities.
Thetoweringwaves swept clean across the low-lying Maldive Islands, leaving a trail of death and destruction in their wake.
A list of the dead at one hospital in northern Indonesia showed that many children were victims: too weak to swim, and too small to climb to one of the few safe havens, they drowned.
Indonesia sits on the so-called "ring of fire," a highly active seismic band where plates of the earth'scrustcollide.