As the people of West Sumatra gather the ruins of their lives around them and slowly start again, forced to accept there are bodies that will never be recovered from last week's earthquake and landslides, residents of Aceh can only watch with sorrow and understanding.

They have seen it all before – only far, far worse – and they know there is no point giving up or looking back. Banda Aceh storekeeper Radiah Abdullah puts it as well as anyone: "We just have to accept what Allah gives us."

Mrs Abdullah survived the 2004 Indian Ocean tsunami by sheer good luck. Seven months pregnant, she climbed to the top floor of a neighbour's three-storey house as the ocean roared towards her at 300km/h, and then on to a nearby giant electricity company generator barge driven 5km inland by the raging waters.

Her husband, at a popular recreational angling spot at the time, perished. His body was never found. Their now four-year-old son, when asked what he understands of his disappearance, says simply: "My father is fishing. He's not coming home."

The barge on which Mrs Abdullah took refuge that day remains where it came to rest on top of an unknown number of bodies, a monument to the massive toll – 126,000 died in Sumatra alone, and about 350,000 in all the affected countries – and the random nature of fate.

The land around it has been reserved, never to be built on. A peace park winds its way along one side, children playing on monkey bars among neatly arranged gardens and, at one end, a small kiosk houses a display of the horrors of that Boxing Day morning and the days that followed.

It is not possible to sanitise the past when the past is this bloody. An exhibition of explicit photographs, slowly fading reddish from the sun but still all too clear, is reminder enough of what everyone here lived through.

Four dead infants, lined up alongside each other, faces undamaged, beatific. Row upon row of bloated humans, arms sticking straight up at wrong angles in the death rigor, laid out in the sun as the living peer desperately across, searching for the missing. Piles of bodies stacked in disorder on the backs of trucks, waiting to be disposed of.

A visitor from Lhokseumawe, more than 300km to the south, clicks her tongue, muttering as she moves from one photo to the next. "It's just sad, so sad." Her young daughter is with her, silent.

And still these pictures do not tell of the awful stench that hung in the air across Banda Aceh in those days, the greasy death perspiration that trickled down the skin, the putrid, rancid mud that was in everything, the sight of dogs feeding on human corpses by the side of the road. These things were all real.

Council worker Mohammad Kasim supervised the burial of 46,718 people in a mass grave in Ingin Jaya district. He knows exactly how many went into the ground "because I made a note of every one that came here, each time new ones came, and we dug holes, 8m deep, and into each hole went as many as 300 bodies". He paces out a space 4m by 4m to illustrate. "That's how big each hole was. For 300 bodies. We dug them with backhoes."

The Ingin Jaya mass grave has become a memorial park, with a concrete wave sculpture more than 12m tall rearing up in one corner. Visitors are constant. A small group of men and women sits in the shade of a hut, singing verses from the Koran in low voices. Prayer here is the order of the day.

During the just-finished Muslim holy period of Idul Fitri, the joyous climax to Ramadan when wrongs are forgiven and peace made with the past, this park swarms with people.

Few can be sure if they're at the right spot, the place where their father or mother or sister or brother or next-door neighbour is buried. It's not the only mass grave in Banda Aceh – just the biggest. And in those early days of the crisis, when civil administration was wiped out and public health a far greater priority than social nicety, if you couldn't find a loved one quickly, you weren't likely to ever discover which hole they'd been shovelled into.

Memorials to the disaster are dotted across the worst-hit parts of Banda Aceh, some of them remarkably reminiscent of the war memorials of country Australian towns, with names chiselled on marble to remember those who never returned.

Everywhere, across a city that was in places wiped out, buildings have sprung up again, all bright red-and-blue tiled and corrugated zinc roofs. In the first days of the emergency you could see clear to the coast from kilometres away, because the trees and houses that had been there no longer stood.

Now they are back, each construction proudly declaring which part of the world sponsored its return to life, as billions of dollars in aid and reconstruction money flowed in to Aceh.

A madrasah – a Muslim school run by the Religion Department, under the two-tier Indonesian education system – has been built by Islamic Relief and Austcare, and funded by the Wollongong Community, according to its foundation stone.

But the death memories never go away. Everything in Aceh now is measured by a new scale, one whose starting point is piles of bodies scattered across the city and the countryside, and across dreams. Across nightmares.

The labourers at the Lhokgna memorial park want to know how the bodies produced by West Sumatra's disaster last week compare to those of Aceh.

"There, they are crushed or they are buried. You don't even see them. Here, they were carried on the water, scattered, left wherever they fell," says one. "They were everywhere."

For Mrs Abdullah, the news from Padang and the hillside areas of Pariaman and even further north, where hundreds died in landslides triggered by the earthquake, was like a spear through the heart.

"I cried, I couldn't say a thing; I cried remembering what happened to me back then," she says. "Now it's our neighbours and our brothers and sisters who are experiencing it."

Retired civil servant Syamsuddin Mahmud says that even though his own tsunami trauma is over, watching the grief of Padang over the past week and a half brought back much of the pain.

"We saw it on TV, for a week people who couldn't get out (of ruined buildings), trapped people crying for help; this is what was so sad," he says. "For Acehnese, the suffering lasted 15 minutes and then you were dead."

And as the shock and pain recede, West Sumatra will begin facing its huge reconstruction challenge.