Rescue efforts were under way in southwestern Japan on April 16 after two powerful earthquakes hit the area, killing at least 39 people.
Hundreds of people were believed trapped and authorities briefly issued a tsunami warning after a magnitude 7.1 temblor was followed by a strong aftershock that measured 7.4.
On April 14, a magnitude 6.5 earthquake struck the area at a depth of 11 kilometers.
The epicenter was near the city of Kumamoto, a city of 740,000 inhabitants on Kyushu, the southernmost of Japan's four main islands.
Some 20,000 soldiers were being deployed to the area over the weekend to help rescue efforts.
More than 1,000 people were injured, with about 190 of them in serious condition, the government said. Dozens of others are feared trapped in the rubble of collapsed buildings.
The authorities say some 200,000 households remain without electricity and more than 420,000 homes are left without running water.
Some 1,000 buildings have been damaged in the quakes and many roads have cracked. Big landslides have blocked roads in the area and there are fears that forecast heavy rain could set off more landslides.
The Japanese Meteorological Agency, meanwhile, reported a small eruption on Mt. Aso, which is volcanic, with smoke rising about 100 meters into the air.
But the agency said it was keeping its alert level at 2 on a scale of 5.
The epicenters for both temblors have been relatively shallow -- about 10 kilometers deep -- and close to the surface, resulting in more severe shaking and damage.
Japan is one of the most seismically active countries in the world.
A massive undersea quake on March 11, 2011, sent a tsunami slamming into the country's northeast coast that resulted in about 18,500 people being killed or missing.
Several nuclear reactors went into meltdown at the Fukushima plant, which became the world’s worst atomic accident in a generation.
A government spokesman said a nuclear plant on Kyushu was unaffected by the April 15 quake.