Survivors of Asia's 2004 tsunami and relatives of its 226,000 victims cried and prayed as they gathered along Indian Ocean shorelines on Friday for memorials to mark the 10th anniversary of a disaster that still leaves an indelible mark on the region.

When a 9.15-magnitude quake opened a faultline deep beneath the ocean on Dec. 26 a decade ago, it triggered a wave as high as 17.4 metres (57 feet) which crashed ashore in more than a dozen countries, wiping some communities off the map in seconds.

Hundreds gathered in Indonesia's Aceh province, many bursting into tears as poems and songs were heard and a montage was screened showing the devastation from a disaster that killed 126,741 people in Aceh alone.

"It seems there's no bigger lesson to Aceh than this. It is as if the souls of the dead are still with us," said provincial governor Zaini Abdullah, formerly a prominent figure in a long-running separatist conflict the tsunami helped end.

Vice President Jusuf Kalla said the memorial brought him to tears but he took solace in a peace deal that proved adversity could bring people together to reconcile differences.

Mass prayers were held late on Thursday at Banda Aceh's Grand Mosque, one of few buildings that withstood the wave.

"Allah kept his house unscathed," said Azman Ismail, the Great Imam of the Masjid Baiturrahman mosque.

Relatives of victims also prayed at the graves of loved ones in Hambantota, Sri Lanka, where 677 Muslim families were relocated after the tsunami destroyed their village. Some 40,000 people were killed in Sri Lanka, but heavy rains in Hambantota forced the cancellation of memorial events there on Friday.

VILLAGES FLATTENED

Fisherman Tuan Ilyas Idrees, who lost 10 family members, was deep in prayer after finding his dead mother close to a coconut tree by a mosque.

Idrees tearfully said his entire village was wiped out.

"I ran to my house to save my mother and others, but in just five minutes, there was no house at all," Idrees said.

"We buried hundreds of bodies here."

Crowds also gathered and laid wreaths at Thailand's tsunami memorial park in Ban Nam Khem, a southern fishing village decimated by the wave.

Some 5,395 people were killed in Thailand, among them about 2,000 foreign tourists. Almost 3,000 people remain missing.

Eighty percent of Thailand's victims were killed in the province of Phang Nga, where experts from 39 nations quickly gathered to identify bodies in what became the world's biggest international forensics investigation.

About 700 people carrying flowers and banners marched from the beach where the wave smashed against India's southern Tamil Nadu coast to a black granite memorial, stopping by a Christian shrine to pray for the dead. An inter-faith ceremony was held for the 6,000 who died in Tamil Nadu, featuring Christian hymns and verses read from the Koran and Hindu texts

Illaycha, who lost five children, was inconsolable as she lit a candle. "I'm praying to the gods that they should take care of them in heaven," she said.

Tsunami escape drills were to be held to demonstrate the readiness of Tamil Nadu's large fishing community.

But doubts linger about how ready countries on the Indian Ocean really are for another giant wave. The past decade has seen more than $400 million spent across 28 countries on an early-warning system comprising 101 sea level gauges, 148 seismometers and nine buoys, but there are concerns about the effectiveness and maintenance of the systems in place.

Some experts say complacency is leaving millions vulnerable.

Abdullah, Aceh's governor, said lessons must be learned.

"This experience reminds us that Indonesia is a place prone to natural disasters," he said. "We have to prepare when disaster comes, so we can mitigate it fast and right."