By Andrew North
BBC News, Meulaboh, Aceh, Indonesia
Whole communities have been wiped out
The heart of Meulaboh has been ripped out.
It is almost impossible to take in the scale of devastation in this remote town on the western coast of Aceh.
Nobody knows how many have been killed. But relief agencies are estimating that around 40,000 people in the town died.
After flying in with a Red Cross relief team, I drove into the town for about half an hour along a coastal road.
Every village that we passed - and almost every house - had been destroyed.
In many cases all you see is the outline. The foundation of the house, the walls and everything that remained has been swept away by the surge.
In some cases the road has been gouged out, bridges have been damaged and power lines are down. Everything is covered in stinking mud.
But it is believed there are possibly thousands of bodies decaying under all this debris - and in many places you can smell this decay.
Hundreds of little flags mark points in the town where bodies have been found.
There are some survivors among this scene of ruin - cooking food, sorting though the debris. I saw one family starting to build some kind of shelter, on what appeared to be the remains of their house.
But in most cases the few survivors are sitting around, looking dazed.
Officials are calling for relief efforts to be stepped up as evidence emerges of the scale of destruction.
Some have lost everything
There is serious concern about sanitation and the spread of disease, particularly because very little aid is reaching this region.
There are a few pockets of relief workers trying to distribute supplies - but one of the problems is that even the airstrip was destroyed in many places by the force of the surge.
Many people have been injured and are now suffering from infected wounds in this warm, damp climate.
Local authorities are organising the relief efforts for the survivors. But thousands are living in temporary shelter, including hundreds crammed into the town hall.
But if things are bad in the town, they are much, much worse for people in outlying villages.