Banda Aceh, Indonesia ? After the devastation wreaked by the seas, a deluge from the skies deepened the misery for tsunami-stricken areas Saturday, triggering flash floods in Sri Lanka that sent evacuees fleeing and increasing the threat of deadly disease. U.S. forces began one of their biggest relief missions ever with the death toll likely to hit 150,000.

A 5.9 quake rocked Sumatra on Sunday, the second strong aftershock on the hard-hit island in two days. But there were no reports of further damage or injury.

The world’s efforts shifted into high gear in ways big and small: elephant convoys working in Thailand, global assistance reaching $2 billion with a fresh pledge from Tokyo, and aid-bearing American helicopters touching down in Indonesia to the joy of tsunami survivors.

The confirmed death toll from the quake and tsunamis that hit a week ago Sunday passed 123,000, and the United Nations has said the estimated number was approaching 150,000.

U.N. Secretary-General Kofi Annan decided to visit Indonesia, the hardest-hit nation, where the official death toll stood at more than 80,000, but officials said it could reach 100,000.

Annan will attend a conference Thursday in Jakarta on organizing relief.

“We mourn, we cry and our hearts weep to witness thousands of victims sprawled everywhere,” said Indonesian President Susilo Bambang Yudhoyono, touring the damage on Sumatra island, which bore the brunt of both the quake and the waves.

In eastern Sri Lanka, flash floods forced the evacuation of about 2,000 people already displaced by a tsunami that killed nearly 29,000 people on the tropical island.

Several roads leading to Ampara — one of the hardest hit towns — were flooded, preventing relief trucks from arriving, said Neville Wijesinghe, a senior police officer. Bureaucratic delays, fuel shortages, impassable roads and long distances also blocked supplies.

In addition to the deaths, 5 million people were homeless.