The United Nations, which estimates 6.6 million people live in the districts affected by the earthquake, is helping to co-ordinate rescue efforts.
Many have been left homeless by the disaster and the country is already reported to be running out of water and food. There are also frequent power cuts.
The British organisation, Search and Rescue Assistance in Disasters (SARAID) has sent a team of experts with 1.5 tonnes of specialist equipment. This includes an electrical power generator and power tools for cutting through concrete and steel.
They also have their own tents and food supplies, so they will not be a drain on local resources.
India and China are among the other countries to send teams of rescuers.