A huge earthquake off northwest Indonesia killed at least 400 people, and possibly several thousand, and triggered tsunami warnings which caused panic across the Indian Ocean. The epicenter of the quake measuring 8.7 on the Richter scale was just 200 miles from that of the December 26 quake which sent giant waves crashing into 12 nations, killing over 273,000 people.
Indonesian officials said at least 400 people had been confirmed dead on Nias and Simeulue islands off Sumatra. But Vice President Yusuf Kalla told the BBC that reports from Nias indicated 1,000 to 2,000 people had been killed.
The undersea quake struck about 200 kilometers off the west coast of Sumatra and prompted Indonesia, India, Malaysia, Sri Lanka and Thailand, among others, to issue warnings of imminent tsunamis.
Alerts rang out on television and radio, while police and local residents tried to shepherd people to safety away from the coast towards high ground.
But the giant tsunamis never materialised and three hours after the quake Indonesia and Thailand gave the all-clear. Sri Lanka and India followed several hours later.
"There have been tsunamis recorded as a result of the quake but apparently they were not destructive," said Dr. Laura Kong, director of the Hawaii-based International Tsunami Information Center which sent tsunami warnings to Asian countries.
While the region was spared a new tsunami horror, the earthquake caused widespread destruction on Nias, an island of 700,000 people which is popular with surfers.
Agus Mendrofa, a district official, said at least 80 percent of all multi-storey buildings in the main city of Gunung Sitoli had been destroyed, leaving many people feared trapped under rubble.
He said many victims had not received medical treatment as the main hospital had been hit by a blackout and many doctors had fled to nearby hills.
"Power poles fell and roads were broken. Electricity and fixed telephone lines are dead. Thousands of people have fled to the hills," Herman Laia, an environment official in the south of Nias, told Elshinta radio.
However T.B. Silalahi, an envoy sent by President Susilo Bambang Yudhoyono to assess the destruction, said after flying over Nias that earlier reports may have overestimated the impact.
"I think the devastation is not as massive as previously reported by local officials because they made their report during the night while we have had the opportunity to witness the damage from the air," said Silalahi.
An AFP reporter who flew with the envoy in the chartered aircraft as it passed over Gunung Sitoli said damaged buildings with collapsed roofs were clearly visible.
But he said the level of destruction was nowhere near the scale wrought on the Sumatra coastline by the December 26 tsunamis.
Mar'ie Muhammad, chairman of the Indonesian Red Cross, said the first aid teams landed on Nias and the nearby island of Simeulue in light aircraft.
A military official said a three-metre wave had smashed into a port on Simeulue, causing extensive damage and unconfirmed reports of casualties.
Indonesian President Susilo Bambang Yudhoyono delayed a planned trip to Australia and was making plans to visit Nias. Canberra promised one million dollars (774,000 US) in aid.
The earthquake evoked bitter memories of the December disaster in which a 9.0-magnitude quake triggered waves 15 metres high that roared across the Indian Ocean at speeds of up to 700 kilometres per hour.
Those waves killed more than 273,000 people including over 220,000 in Indonesia, 30,000 in Sri Lanka, 10,000 in India and 5,000 in Thailand.
Some 10 billion dollars in aid was pledged to affected countries, and governments promised to create a high-tech tsunami early warning system for the Indian Ocean by mid-2006.
Although no formal warning system was yet in place, the Japan Meteorological Agency and the International Tsunami Information Center contacted countries around the Indian Ocean immediately after detecting the huge quake.
Thai Prime Minister Thaksin Shinawatra said the makeshift warning system had worked well. "Although our warning system is not yet complete, we managed to alert people in enough time for them to seek safety," he said.
Kerry Sieh, a seismologist with the United States Geological Survey, said the quake was one of the top 10 most powerful in the last century.
Tremors shook many parts of Sumatra for three minutes and rocked the neighbouring countries of Malaysia and Singapore where people fled high-rise buildings.
"When the earthquake happened, I rode my motorcycle to the airport because I was very afraid the tsunami would hit again," said university student Heri in Banda Aceh, the capital of Indonesia's devastated Aceh province.
In northwestern Sri Lanka people ran to temples and churches where bells were rung to warn people to run to high ground. In the resorts of southwest Thailand holidaymakers fled hotels as television flashed warnings.
Hundreds of people, with children yanked from their beds and still wearing pyjamas, gathered at the town hall on the Thai resort island of Phuket.
Thai television showed people mounting motorcycles and climbing into pickup trucks as traffic clogged the streets leaving Phuket's Patong beach.
In India's Tamil Nadu state radio stations warned people to move away from the ocean. "People are very tense as they fear that another tsunami is going to hit our coasts. Many of our fishermen have gone to the sea and we are praying for their safe return," Xavier Lawrence, a priest in the town of Kanyakumari, told AFP.
The quake caused tsunami alerts as far away as the Indian Ocean islands of Mauritius and Madagascar, which is over 4,000 kilometres from the epicenter.