Officials issued a tsunami warning for as far away as Sri Lanka.

The US Geological Survey said the temblor, which occurred at 11:09 pm local time (11:09 am EST), measured a magnitude of 8.2. A later reading put the magnitude at 8.7, said Paul Earle, a USGS research geophysicist.

Tsunami warnings were issued in Thailand, Japan and Sri Lanka, although officials in Thailand later called it off for that country. The only tsunami reported within four hours was a tiny one - less than 4 inches - at the Cocos Islands, 1,400 miles west of Australia, meteorologists in Sydney said.

The worst damage was reported on Nias Island, off the Sumatran coast, close to the epicenter of the earthquake, and dozens may be buried in the rubble, said Agus Mendrofa, deputy district head on the island.

"Hundreds of buildings have been damaged or have collapsed. People who were standing fell over", Mendrofa said. "We're not sure about casualties, but there may be dozens of people buried in the rubble."

UN disaster relief coordinator Jan Egeland said there were unconfirmed reports of deaths. "The hard-hit population of western Sumatra have been again struck by a very large earthquake," Egeland said.

Nias, a renowned surfing spot, was badly hit by the December 26 earthquake and subsequent tsunami that killed at least 175,000 people in 12 Indian Ocean nations and left another 106,000 missing. At least 340 residents of Nias perished and 10,000 were left homeless.

Indonesian officials said the quake's epicenter was 56 miles south of the island of Simeulu, off of Sumatra's western coast, and just north of Nias. It was described by one of the agency's geologists as an aftershock of the devastating December 26 quake.

An aftershock measuring 6.0 was reported in the same region nearly 30 minutes later, the USGS said.

Addressing thousands in St Peter's Square, the pope said people of the 21st Century risked becoming "victims of their intellectual achievements". He decried the "menace" of terrorism, the "humiliation" of worldwide poverty and said pandemics and environmental destruction were dangerous new threats.

The Pope followed in the footsteps of his predecessor who died in April. Thousands of pilgrims, tourists and Romans gathered at a rain-soaked Vatican to hear Pope Benedict speak.

Fairness and wisdom: He urged the crowd not focus entirely on the "immense progress" made in science and technology during the previous millennium. "The men and women in our technical age risk becoming victims of their own intellectual and technical achievements, ending up in spiritual barrenness and emptiness of heart," the Pope said.

His warnings about the series of dangers facing humanity today came ahead of traditional prayer calls for peace and goodwill around the world. He prayed for those working for peace and against conflict in Africa and Asia, and for harmony in Latin America. In the Holy Land, Iraq and Lebanon, the pope said, signs of hope need to be confirmed by action inspired by "fairness and wisdom".

As Christmas began, the head of Iraq's Chaldean Christian church prayed for peace in Iraq and elsewhere. Ceremonies in Baghdad were held before dusk on Saturday in advance of a curfew. "I do not want to make a distinction between Christians and Muslims, we are all Iraqis," said Emmanuel II Delly. "A car bomb kills without distinguishing between Christians and Muslims."

In Bethlehem, revered as the birthplace of Jesus, Latin Patriarch Michel Sabbah, the senior Catholic cleric in the Holy Land, said the region was "thirsting for peace". "God created you not to fear or to kill each other but to love each other, to build and to cooperate together," he told crowds in Bethlehem, where Palestinian leader Mahmoud Abbas was attending his first Christmas Eve service.

August's Hurricane Katrina in the US alone is expected to cost $45 billion in claims, the world's second-biggest reinsurance company said. This will make it the most expensive ever insured single event.

Total economic losses caused by hurricanes, earthquakes and floods in 2005 reached $225 billion in 2005, it said.

Hurricane Andrew in 1992 was previously the most expensive single catastrophe, causing losses of $22 billion, Swiss Re said.

This was followed by the 11 September 2001 attacks on the US, costing nearly $21 billion.

Two other expensive storms in the US came in the wake of Katrina. Hurricane Rita cost $10 billion in insured losses and Wilma claimed $8 billion.

"The ongoing warm phase that has been measurable since the 1990s and the recent high hurricane frequency inspire little hope of the trend being reversed any time soon," Swiss Re warned.