Two years after a devastating tsunami crashed into coastlines, villagers in hardest-hit Indonesia were preparing for future disasters, with thousands expected to flee their homes by foot and car in an early warning drill.

Elsewhere across the tsunami disaster zone, survivors and other mourners will visit mass graves, light candles along beaches and listen to temple bells chiming to mark the moment the waves hit two years ago Tuesday.

"We hope this will be part of the healing process for those who lost loved ones," said Chamroen Tankasem, a government official in southern Thailand, a tropical paradise that was turned into a graveyard in a matter of minutes.

"It will also help us remember what happened, what we have learned since ... and what more needs to be done for the people affected."

The magnitude-9.0 earthquake that ripped apart the ocean floor off Indonesia's Sumatra island on Dec. 26, 2004, spawned giant waves that fanned out across the Indian Ocean at jetliner speeds, killing an estimated 230,000 people in a dozen nations.

Walls of water two stories high swept entire villages to sea in Indonesia and Sri Lanka, submerged luxury resorts and fishing communities in Thailand and destroyed thousands of homes in India.

Indonesia, which is prone to seismic upheaval due to its location on an arc of fault lines, accounted for nearly two-thirds of those killed. It will mark Tuesday's anniversary by preparing for future deadly waves.

Ten thousand people are scheduled to take part in an evacuation drill on the resort island of Bali, which was unaffected by the 2004 tsunami, fleeing homes in four villages after authorities set off sirens, said Pari Atmono, a Ministry of Research and Technology official.

A smaller drill will be held in the Sumatran town of Padang, which geologists warn could be hit by another massive tsunami within 30 years. Mourners in devastated Aceh province will visit mosques and mass graves.

In Thailand, ceremonies will be held along the Andaman coast with Buddhist prayers to remember the more than 8,200 killed. Balloons will be launched and candles lit along beaches once again filled with sun-seeking tourists.

Authorities also will open a cemetery for hundreds of unidentified tsunami victims.

In Sri Lanka, where the resurgence of a civil war has added to the misery of survivors, Hindu and Buddhist temples will ring bells to mark the time the first wave hit. Two minutes of silence will follow to remember the 35,000 killed there and interfaith ceremonies will be held in India, where another 18,000 are believed to have died.

The 2004 tsunami generated an unprecedented outpouring of generosity, with donor pledges reaching some $13.6 billion, but many of the 2 million made homeless complain they still do not have adequate places to live.

Some survivors say they are stuck with poorly built structures that leak, are termite-infested or located in flood zones. Several aid agencies, meanwhile, have been forced to delay projects or rebuild homes after contractors and suppliers ran off with the funds.