Meanwhile, radiation rose to unusually high levels on Saturday after the quake near Japan's Fukushima Number 1 nuclear plant.
But the nuclear safety agency said the radition levels do not pose an immediate threat to the health of residents.
Radiation levels in the Number 1 plant rose to a thousand times the normal level and there are concerns that radioactive steam could spread around the facility.
The plant operator plans to release pressure from both the Number 1 and Number 2 plants in Fukushima Prefecture, in northeast Japan as the cooling system failed on Saturday at the number 2 plant.
Meanwhile, Japanese Prime Minister Naoto Kan left Tokyo by helicopter on Saturday morning and visited the Fukushima Number 1 plant and ordered the evacuation area for nearby residents to be expanded from a 3 kilometer radius to 10 kilometers.