Efforts are continuing in Japan to locate and rescue thousands of people still unaccounted for after Friday's earthquake and tsunami.
One-hundred thousand Japanese troops are now involved in rescue and relief efforts. They are using helicopters to reach many trapped after a massive tsunami washed away wooden homes and buildings in several coastal communities.
Japan has received offers of aid from 69 countries. Teams from South Korea and the U.S. military are on the ground and a 15-member team from the China Earthquake Administration arrived midday Sunday. U.S. Ambassador to Japan John Roos said the United States is ready to offer help.
"The United States is absolutely committed to helping Japan in anyway possible to respond to and recover from the tragedy of the past few days," he said.
In areas near the quake zone, food and gasoline are in short supply. Even in central Tokyo, the shelves of many convenience stores are empty of fresh food.
On Sunday the government warned that rolling blackouts would begin on Monday because electricity supply is not expected to keep up with demand.
Speaking at a Tokyo news conference, Chief Cabinet Secretary Yukio Edano explained the reasons for the blackouts.
Edano said the government will begin coordinating with power companies on the black outs, which are necessary because several nuclear power stations have been shutdown by the quake. He asked companies and individuals to do all they can to conserve power.
As Japan comes to terms with the scale of disaster, the government has revised its estimates of the size of the earthquake.
At a news conference, Japan's Meteorological Agency said the trembler that struck Friday was actually three large earthquakes in quick succession. Agency officials raised the magnitude to 9, making it the world's fourth largest recorded earthquake. They also warned of more strong aftershocks to come.
The agency said there is a 70 percent chance of a magnitude 7-class earthquake in the next three days.