Aid workers in Indonesia are finding things are much worse than they thought after the earthquake on 26 December.
In some villages in the Aceh province 80% of the people living there before the quake and the tsunami that followed it have been killed.
Of the 140,000 people killed in the region it's thought as many as 94,000 Indonesians lost their lives.
Earlier on Tuesday a blocked runway at an airport made it difficult to get aid into Indonesia until it was cleared.
The airport is very important in getting water, food and medicine to areas in Indonesia struck by the 26 December earthquake and waves.
The UK Government said that up to 200 Britons may have died in the tragedy, including 25 children.
Getting food, water and medicine to people is very important
It said that 40 Brits had been confirmed dead and a further 159 were "highly likely" to have been killed.
A three-minute silence for the victims of the disaster is being held in Britain on Wednesday.
Sumatra was near to the centre of the earthquake which sent giant waves crashing into 11 countries.
Around 5m people have been made homeless after the disaster nine days ago.