A powerful 7.3 magnitude earthquake struck southern Japan early on Saturday, killing at least 20 people, injuring more than 1,000 and trapping people in collapsed buildings, barely a day after a quake killed nine people in the same region.
Rescuers dug through the rubble of collapsed buildings and mud and debris on Saturday to try and reach those trapped, but continued aftershocks hindered rescue efforts and fueled fears of more powerful quakes.
"Nothing is more important than human life and it's a race against time," said Prime Minister Shinzo Abe, warning rescue efforts were critical with wet weather forecast overnight, which could further damage weakened buildings and cause landslides.
"I want rescue activities to continue with the utmost effort," Abe said at a government meeting after the disaster.
The epicenter of the quake was near the city of Kumamoto on the southern island of Kyushu and measured at a shallow depth of 10 kms, the USGS said.
Television footage of the area showed fires, power outages, collapsed bridges and gaping holes in the earth. Residents near a dam were told to leave because of fears it might crumble, broadcaster NHK said, while the 400-year-old Kumamoto Castle in the center of the city was badly damaged.
"I don't mind standing in line. I'm just thankful for some food," said a man in his 60s waiting in line for meals served by Self Defense Forces personnel in the town of Mashiki, close to the epicenter.
Factories producing auto parts and tech components for companies including Sony Corp and Honda Motor Co halted production as they assessed the damage.
The quake triggered a tsunami advisory which was later lifted and no irregularities were reported at three nuclear power plants in the area, a senior government official said. People still reeling from Thursday's 6.4 shock poured onto the streets after the Saturday earthquake
