Millions of people were reported homeless in a wide swath from Indonesia to the Indian subcontinent. Whole villages were missing and the wreckage was too extensive for any reasonable estimate of the cost beyond many of billions of dollars. It will likely take years to rebuild.
Children and the young were believed to be the largest group of victims, creating the likelihood that the quake's woes could spread to future generations. Because Asia has a large number of children, many of whom work with their parents, United Nations officials estimated that perhaps half of the dead were children. The young will be an especially high proportion of those who will die from hunger and disease in coming days and weeks, officials said.
At least 27 aftershocks have been reported from the 9.0 Sunday quake in the waters off Indonesia.
Experts warned that the aftereffects were likely to be even more deadly. Disease, spread from rotting corpses, starvation and lack of drinkable water all threaten to keep killing for weeks.
Officials across the region increased the death toll as each grim minute brought new discoveries. Sri Lanka reported more than 12,000 dead; Indonesia put the number of bodies at more than 5,000. India said more than 7,000 had died. Thailand reported almost 1,000 bodies; while Malaysia, Maldives and Myanmar all reported initial death tolls in the hundreds.
Even 3,000 miles away in Africa, Somalia reported hundreds had been killed.
The disaster was an equal opportunity killer, claiming rich Western tourists, impoverished native fishermen and revelers seeking a holiday beach break. The 21-year-old grandson of Thailand's King Bhumibol Adulyadej was among those killed when the motorized ski he was riding on the ocean was overwhelmed by the towers of water.
The catastrophe began when the earthquake, the world's biggest in 40 years, struck just before 7 a.m. Sunday beneath the Indian Ocean, 155 miles southeast of Banda Aceh on the Indonesian island of Sumatra.
The quake spawned tsunami waves, some traveling at 500 mph and rising 30 feet into the air. Television images captured the unrelenting sea pouring across deserted beaches, smashing everything from huts to hotels.
The U.S. and the European Union immediately pledged millions of dollars of aid to relief agencies, but it was unclear how quickly any group could deal with the needs.
It will take "many billions of dollars" and a number of years to bury the dead, battle disease and recover, said Jan Egeland, who heads the U.N. Office for the Coordination of Humanitarian Affairs.
The deadly wave probably will have the biggest impact of any natural disaster in the five decades that the United Nations has been coordinating the global response, because it struck so many heavily populated areas, Egeland told reporters.
The tsunami struck a year to the day after an earthquake killed 31,000 and left 100,000 homeless in the Iranian city of Bam. That disaster led to an outpouring of aid.
Officials began organizing airlifts to devastated Asian countries, and in some areas the military was mobilized to bring in supplies.
More than 100 foreigners from 23 countries were reported killed, and perhaps four or five times that number were believed missing, officials said.
For parts of the United States and Europe, the impact was as profound as if it had happened on local streets. People in Asian communities desperately sought information about missing relatives and collected money to send abroad.
The tsunami waves traveled through a region that lacks any warning system. Ocean buoys in a tsunami warning network can alert people to a lethal wave's approach hours before it hits, giving them time to move to higher ground.
Tsunamis hold a special fear for the West Coast of the U.S. In Oregon, Washington, Alaska and Hawaii, blue-and-white tsunami evacuation route signs remind coastal residents of the danger of gigantic earthquake-driven waves, but California officials have yet to install road signs to show millions of Southern Californians the best routes to refuge.