Banda Aceh, Indonesia ? Mourners returned to battered shorelines today to mark one year since the Indian Ocean tsunami crashed ashore in a dozen countries, laying waste to coastal communities and killing at least 216,000.

Under a clear sky and before a gentle sea, survivors, friends and relatives of those who died and world leaders commemorated those lost in one of the worst natural disasters the modern world has experienced.

In Indonesia’s Aceh province, which was closest to the earthquake that spawned the waves and bore the brunt of the disaster, President Susilo Bambang Yudhoyono led hundreds of other officials in a minute’s silence at a ceremony held on a jetty overlooking the sea.

“It was under the same blue sky, exactly one year ago that mother earth unleashed her most destructive power upon us,” Yudhoyono told the gathering.

Similar periods of silence were to be observed at official ceremonies in Thailand and Sri Lanka, where flags would be lowered to half-staff and bells rung in remembrance. Muslim, Christian, Buddhist and Hindu prayers services were being held across the tsunami zone.

Some preferred more personal reflection.

An Acehnese woman weeps with her relatives at a mass grave in Banda Aceh, Indonesia. Banda Aceh was ground zero for the deadly tsunami that surged across the Indian Ocean one year ago today.

In Thailand, one man sat in the sand, a bouquet of white roses laying in front of him. The man, who declined to talk to a reporter, was among scores of Westerners who traveled to sites along Thailand’s world famous beachfront where their loved ones disappeared into the waves.

Ulrika Landgren, 37, of Malmoe, Sweden, brought her 9-year-old son to Patong beach where nine friends died.

“Somehow it’s good to see this place,” she said, tears falling from behind her sunglasses.

Massive forces

One year ago today, a magnitude 9 earthquake – the most powerful in 40 years – ruptured the sea floor off Sumatra island, sending waves 33 feet high across the Indian Ocean.

They crashed ashore in a dozen countries, sweeping entire villages away in Aceh and Sri Lanka, swamping resorts in Thailand and surging into coastal communities from India to east Africa.

At least 216,000 people were killed or disappeared, The Associated Press found in an assessment of government and credible relief agency figures in each country hit. The United Nations puts the number at least 223,000, though it says some countries are still updating their figures.

The true toll will probably never be known – many bodies were lost at sea and in some cases the populations of places struck were not accurately recorded.

In Aceh, Yudhoyono set off a siren at 8:16 a.m. to mark the moment the first wave struck. The siren is part of a tsunami warning system that did not exist last year.

An unidentified Australian family tosses flowers into the surf on Patong Beach, in Phuket, Thailand, today following memorial services. Mourners returned to battered shorelines today to mark one year since the Indian Ocean tsunami crashed ashore in a dozen countries, laying waste to coastal communities and sweeping away at least 216,000 lives. More than 25 Australians were killed in the tsunami.

He later scattered petals over a grave holding almost 47,000 bodies that were hastily buried in the days after the disaster to clear the streets of the provincial capital, Banda Aceh, of corpses.

Hundreds of people gathered at a mosque in Kajhu village for one of scores of prayer ceremonies in Aceh.

“It is important for me to come here to pray for my family, may they rest in peace,” said Darmawati, 39, who lost her husband, two daughters and both parents in the disaster. “I pray that God will give me strength to raise my only son who survived.

Relief and recovery

The tsunami generated one of the most generous outpourings of foreign aid ever known. Some $13 billion was pledged to relief and recovery efforts, the U.N. says, of which 75 percent has already been secured.

But the pace of relief and reconstruction has been criticized, and frustration has grown among some of the 80 percent of refugees who are still living in tents, plywood barracks or the homes of family and friends.

Margareta Wahlstrom, the U.N. assistant secretary-general for humanitarian affairs, said people have to be patient.

“If you don’t do things well they will collapse in a couple of years,” she told AP on Sunday. “If you don’t take time to do proper planning, and ask people what they want … then you are going to create new problems along the way.”

Holiday mood

It was a somber Christmas for many of those who decided to hold private ceremonies Sunday.

Sigi Gsteu, of Feldkirch, Austria, wiped away tears as he told of three close friends who died when the torrents flooded their Thai resort bungalow.

“When a person is missing and you don’t have (a body), you cannot say goodbye,” he said as he set two simple wooden plaques engraved with his friends’ names beneath a lone pine tree where the resort once stood.

Not everyone was thinking of the past, though. Holiday revelers partied with bar staff dressed in Christmas hats in Patong’s notorious nightclub district.