The massive tsunami that crashed into Sumatra island in December ripped Ibu Yusniar's home from its concrete foundation. But while the stout woman survived, wrapping her arms around a column in a nearby mosque to ride out the surging waters, nature was not through.

Three months later, the sea gobbled up part of her land when another huge earthquake struck. Then, the full-moon tides in July completed the job, reducing the balance of her property in Lhok Bubon village to salty swamp.

"The tide came in and it didn't go out," recounted her cousin, Suharman.

More than half a year after the tsunami devastated Aceh province, killing at least 150,000 Indonesians, dramatic shifts in topography are continuing to reshape Sumatra, hampering efforts to conduct the gargantuan task of reconstruction.

The Dec. 26 tsunami submerged swaths of seafront and inundated thousands of acres of rice paddies. The March 28 earthquake, measuring 8.9 on the Richter scale, then lowered the elevation of the island's western coast, dipping much of Aceh's rim into the Indian Ocean. Rain, high tides, westerly winds and erosion have further recast the shoreline and rerouted rivers.

"Things that usually happen over hundreds of years are happening here over three to six months," said Kevin Austin, who completed his tour this month as the U.N. Development Program's chief officer in western Aceh. "This is really a unique situation."

Combined with the herculean labor of carting away millions of tons of tsunami rubble and the Indonesian government's initial confusion over how to allocate resources, the ordeal of mapping villages and assigning land ownership has impaired new housing construction. Officials have estimated that more than 500,000 people in Aceh are still homeless as a result of the tsunami.

Relief agency officials and local activists agree that the pace of activity has accelerated in the last three months after the government set up an authority to streamline reconstruction. The move cleared up much of the earlier disarray caused by overlapping proposals from the scores of agencies working in Aceh and helped secure faster funding from both the Indonesian parliament and abroad.

But none of the major undertakings, such as primary roads, ports and power plants, are close to completion, and smaller projects, including houses and schools, remain relatively few and scattered. Of the more than 200,000 new homes required in the province, Indonesian officials have reported, barely 3,000 have been finished.

Among the areas hardest hit by the tsunami were the villages and towns of Aceh's western coast. In Lhok Bubon, a remote fishing hamlet about 10 miles from the main west coast town of Meulaboh, more than a third of the villagers were killed and about 95 homes destroyed. Half of those were in a neighborhood that has since become uninhabitable marsh.

Most of the survivors have settled in worn, sun-bleached tents pitched, whenever possible, on the razed foundations of their old homes or in shanties cobbled together from scavenged bits of wood, tarp and corrugated metal.

"I had intended to rebuild in the same place, on the existing foundation," said Ibu Yusniar, 43, crouching among a small knot of women beneath a tarp. "But now my land is just water and sand. The land keeps changing. The coast keeps coming. Every tide makes it worse."

She flashed a sad smile. The tsunami had killed many of her relatives but fortunately spared her cousin Suharman, who, like many Indonesians, uses one name. He had agreed to live on a corner of his village property, at a safer distance from the sea, and let her rebuild there.

Suharman, won the approval of the village elders for his plan. But the process of officially registering the titles and starting construction seemed endless, he complained.

Across this damaged village, he and other survivors fretted that it now appeared their new homes would not be ready in time for the start of the Muslim holiday of Ramadan, in October.

"We have no idea when we'll move out of this tent," said Sapuan, 35, a squat woman, her hands clasped tensely in her lap. "It's so hard. Sometimes there are storms. There's rain and wind. Maybe we'll have to stay here."

Two of Sapuan's three daughters were swept away in the tsunami. Her surviving daughter, 10, floated to safety by clutching a bamboo branch.

Beginning next month, World Vision, a Christian nonprofit organization, plans to build 83 new dwellings in Lhok Bubon and complete them by the end of the year, according to Geno Teofilo, a spokesman.

In anticipation, Sapuan and her husband have bought a new lot farther from the beach, paying for the land by working as laborers to clear debris from the village. They daydream about moving to a house in time for Ramadan.

"I really hope we can celebrate the festival in our own home," Sapuan added weakly.

So far, however, there are few signs of progress in Lhok Bubon. Working without heavy equipment, the villagers have excavated the mountains of rubble left by the tsunami and lugged it to the edge of the village. The only new construction is the mosque. Its recently repaired black onion dome rises near the beach.

The most noticeable changes are the topography itself. The waters have recently begun lapping at the mosque's front steps, and coconut palms, decapitated by the tsunami, now jut out from the sea several dozen yards beyond the beach. Fishermen, who once caught snapper and tuna, complain that they are no longer sure where to dock their few remaining boats because the shoreline seems to change daily. The cemetery, where some of Lhok Bubon's 120 tsunami victims are buried, is now underwater.

The shifting shoreline has affected reconstruction all along the west coast, including a U.S.-funded initiative to rebuild the 150-mile highway between Meulaboh and the provincial capital, Banda Aceh, scheduled to start later this month. In the meantime, U.N. officials warn that the province's only major infrastructure project already underway -- the Singapore-funded reconstruction of Meulaboh's port -- could also be jeopardized by the changes.

When disaster struck Lhok Bubon in December, its village chief was killed. A lanky fisherman named Husseini inherited the post. But the fisherman, 33, had lost everything else.

Husseini, at sea during the tsunami, recalled returning in the evening to discover that his house had vanished. He grabbed a tire and floated into the churning waters in a vain search for his wife and 2-year-old daughter. His wife's body later surfaced in a nearby hamlet. His daughter's was never recovered.

Though the villagers fled for higher ground, Husseini returned to Lhok Bubon three days later, almost alone, and erected a tent. There, among the flies, he began to chart the village's revival, soon enlisting the guidance of the Regional Development Foundation, an Indonesian environmental group.

"This situation is so difficult," Husseini said, sitting on a plastic chair inside his tent, his dark eyes sunken and cheeks hollow. Dark stubble cast shadows across his face. "Everything was destroyed. People had nothing left. But people have the spirit to rebuild."

Lost land records pose another problem. International officials are attempting to remap and establish ownership. But months earlier, the villagers of Lhok Bubon began to demarcate the land on their own under the direction of a dour fisherman named Cut Rahman.

"We can't live on tears," said Rahman, 37, turning away as he spoke through a cloud of cigarette smoke. "We don't have the capacity to build houses, but at least we can prepare the groundwork."

Very few of the villagers have managed to salvage their original property. Marzuki, 45, who once owned a kiosk peddling basic household wares, plans to build a new home on upland property where he once grew banana and coconut palms. But, like most villagers, he no longer has the documents to prove his claim. They vanished, along with his wife and son, as he clambered up a palm tree to flee the crush of water.

"My papers? How could I save my land title and certificate?" he asked as his eyes reddened. "I could only save my life. Even my child I couldn't save."

Special correspondent Yayu Yuniar contributed to this report.

Only a few tents stand in a field in Meulaboh. Since the tsunami, an earthquake and high tides have changed Indonesia's coastal topography.Construction workers build a school in Meulaboh. Reconstruction activity in Aceh has accelerated in recent months, but few projects have been completed.A boy fishes in a ditch near the seafront in Meulaboh, on Aceh's west coast. Before the tsunami, the area was crowded with middle-class housing.