Many houses have been severely damaged or flattened following the quake
By Alastair Leithead
BBC News, Sumatra
The earthquake on the Indonesian island of Sumatra left an estimated half a million people homeless, including many in remote areas of Sumatra, where drinking water and medicines are in particularly short supply.
Flying in an aid helicopter above a jungle scarred by landslides, I tried to imagine that moment when the mountains came tumbling down.
The children were playing marbles in the yard, the wedding party was just getting started, the local mosques were preparing for evening prayers.
In the city, two teenage girls were gossiping in the bar below the pool hall, couples were shopping, motorbikes were weaving through rush-hour traffic.
In the hotel, a swimming class was going on, as businessmen hammered out a deal in the conference room.
Nearby, judo practice was in full swing and students who had stayed after school were getting extra lessons.
Then, without warning, it all ended.
We were told over and over again by survivors how the ground shook so hard it was impossible to stand up.
The roads began to tear, the concrete began to give way, buildings started to buckle, and up in the hills the soil turned to liquid.
Unannounced, and from out to sea, a shock wave swept across western Sumatra.
The city was not levelled. One building crumbled while another stood its ground.
Whole villages have been lost, lives have been devastated
How well it was built, what it was built on and precisely how it fell determined who lived and who died - immediately, or slowly and painfully.
Can there be anything more lonely than being trapped under tonnes of rubble, crushed and in agony, hoping someone will come and pull you free?
How many hours, how many days, did some people have to wait - calling out for help, hoping someone would hear them, before their air ran out or their injuries killed them?
It was almost a week later when they heard: "Tolong, tolong, tolong" - "Help" three times in Bahasa Indonesian, coming from the rubble.
After days of pulling out bodies, there was a flicker of hope.
The military listened and heard nothing. The Australian search and rescue team rushed in their special listening equipment, but that hope drifted away.
They were perhaps that unknown woman's last words before she slipped away.
In the hours that followed, the sensors picked up no breathing, no heartbeat.
The building had collapsed in on itself.
Eliana had got out of the swimming pool with the others in her class, but had rushed back to grab something from the changing room.
The next day was to be her 20th birthday. Her mother, who came to the scene day after day clutching her passport photo, never saw her alive again.
The businessmen did not have a chance to get out when the upper floor crashed down on them.
The motorbikes swerved and crashed, some of the cars drove into their riders. The gas pipes broke and the stoves, on which dinner was being cooked when the quake hit, started fires.
Black smoke and a thick layer of crushed concrete dust rose up from the city.
The pool hall collapsed on the two teenage girls who were chatting in the bar. The after-school learners were crushed in their classroom, shoppers were hit by falling masonry.
In the seconds that followed, a young girl in her judo kit emerged from what was left of the building.
The blood flowed down her arm. She began to cry as she realised her nose was broken.
Slowly more of the class came out - some with bones crushed or broken, but they were alive.
Up in the mountains, the wedding party felt the ground shake and they all rushed out of the building, knowing it was safer outdoors.
Then the land slid away from beneath them. They were buried in the valley below, but by chance, somehow, the building was left standing.
The children in the yard playing marbles probably did not even get a chance to see it coming.
Their house, the trees around it, and the mountainside above them was swept into the valley.
We met their cousin two days later. He and the other villagers were digging.
The bodies of two of the nine adults had been found, but none of the seven children had yet been recovered.
"I will give it a week," he said, "and then I will leave them to God."
Rescue teams and soldiers are continuing their search for survivors
Flying over the scene six days on, they were still there, still digging.
Everyone up in those hills knew someone who had lost someone. Zaimar's neighbours were killed, but her family were all fine.
As we walked up to her house, along the small strip of tarmac still left after the landslides, her husband was digging into the collapsed ground floor of their house, trying to pull out a sack of rice.
We asked her to describe what happened and she began to cry uncontrollably.
"I thought the world was ending," she said, and began to pray. The mosque across the road stood ruined and abandoned.
Many terrible things happened just before prayers that Wednesday - the day the mountains came tumbling down and when chance chose who lived and who died.
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