Nearly 250,000 people have been told to leave their homes amid fears of further quakes in Japan, Japan media reports.
Naoki Kokoawai, advisor to the Japanese Red Cross Society, told foreign media that more medical teams were being dispatched to evacuation centers.
Two powerful earthquakes hit the south-western island of Kyushu last week killing at least 42 people.
Japan's meteorological agency has also warned that more tremors are likely to hit in the coming days.
More than 1,000 people are injured and there has been widespread damage to buildings, houses, roads and bridges.
About 30,000 rescue workers are looking for survivors. Police said 11 people are still missing, public broadcaster NHK reported.