Within hours of 30-feet high waves crashing into the coastal villages and seaside resorts of the Indian Ocean on Boxing Day, the directors of UK aid agencies and the Disasters Emergency Committee were discussing how to respond. Indonesia, Sri Lanka, India, Thailand, the Maldives, Malaysia, Bangladesh and East Africa were affected.
As the scale of the disaster became apparent, the BBC and ITV agreed the next day to launch a television appeal, and phone lines were open by 2pm on 28 December.
As the money poured in, aid agencies were allocated money based on their aid spending over the previous three years (see box, right). Because of the need for urgency, they spent contingency reserves and will later claim back their share.
Outlines of relief work being conducted are submitted retrospectively, and the DEC checks that this work is not being duplicated and may ask agencies to discontinue work if it is not needed. If the agencies do not use up all their allocation, it is returned to the DEC to be distributed again.
Aid agencies face a massive task. At least 520,000 people have been injured and more than 1.72 million displaced from their homes.
An Oxfam flight carrying 55 tonnes of bottled water arrived in the Maldives at the end of last week. There are an estimated 30,000 people in the island chain in need of clean drinking water. Relief materials have arrived in Tamil Nadu, the worst-affected state in India. An assessment of 1,000 miles of coastline has found fishing communities devastated. Oxfam has given some funds to the South India Fisherman's Federation. The organisation hopes to reach 250,000 people in Sri Lanka in the next 90 days and has already begun to distribute hygiene kits to 20,000 people in 15 camps.
Four Save the Children trucks arrived in the Sri Lankan province of Matara on 3 January with food and basic medical supplies. The charity is also sending a child protection officer to the Indonesian province of Aceh Besar, where there are more than 700 unaccompanied children.
Save the Children has completed a joint health assessment with UK medical relief agency Merlin in the Ampara district of Sri Lanka, which bore the brunt of the waves. Merlin's team includes medics who responded to the earthquake in Bam, Iran last year.
"It's expected that public health will be the key issue in the aftermath of the tsunami disaster," said Merlin health director Linda Doull.
Cafod's partner in Indonesia, the Jesuit Relief Service, is setting up a tracing service to reunite friends and families. In India, the charity's work has focused on recovering the dead, clearing away the debris and transporting people to safety.
The British Red Cross has spent £9.3m so far, including £4.8m in Indonesia which has been used for tarpaulins, blankets and cooking pots. An emergency response unit has been sent to Sri Lanka and a team despatched to Thailand to help British nationals in Bangkok and Phuket.
A Christian Aid assessment mission arrived in Sri Lanka on 27 December and has been working northwards along the east coast. In the worst-hit province of Thirukovil, the populations of three whole villages are known to have drowned.
Care International has been working in Sri Lanka since 1956 and many of its 250 staff lost homes or relatives in the disaster. Working with the Sri Lankan government, it has delivered relief to more than 60,000 survivors so far.