15 killed in Japan quake

At least 15 people were killed and 760 injured as a powerful earthquake measuring 7.3 on the Richter Scale hit Japan's Kumamoto prefecture on Saturday.

The quake comes close on the heels of tremors felt on Thursday that killed nine people, The Japan Times reported.

Authorities reported of damage over a wide area, as reports came in of scores of people trapped in collapsed buildings, fires and power outages.

The media also reported a "small-scale" eruption at Mount Aso, a large active volcano in Kumamoto. The Japanese Meteorological Agency said it was not clear how the eruption was linked to the quakes.

The powerful shaking also triggered a huge landslide that swept away homes and cut off a national highway in Minamiaso.

Thursday's quake affected old houses, and larger buildings were damaged across Kumamoto, the epicentre of both the quakes.

Local officials said the Aso Ohashi bridge in the village had also collapsed.

Heavy rain forecast for the coming days could cause more landslides and affect already damaged structures, the meteorological agency said.

Kumamoto prefecture police said they have received reports of 97 people trapped or buried under collapsed buildings.

Saturday's temblor triggered a tsunami advisory, although it 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 shock poured onto the streets as the quake struck around 1.25 a.m. (local time) on Saturday.

Prime Minister Shinzo Abe told reporters the government was making every effort to determine the extent of the damage, carry out rescue and recovery, and to get accurate information to citizens.

"It's possible that there may be damage over a wide area," Abe said.

The meteorological agency initially said the Saturday quake measured 7.1 on the Richter Scale but later revised it up to 7.3.

"We would not be surprised to see more earthquakes of this size," said John Bellini, a geophysicist with the US Geological Survey.

A magnitude-9 quake in March 2011 in the Tohoku region touched off a massive tsunami and nuclear meltdowns at Fukushima. Nearly 20,000 people were killed in the disaster.

Japan is on the seismically active "ring of fire" around the Pacific Ocean and has building codes aimed at helping structures withstand earthquakes.

Factories in the area operated by manufacturers including Honda Motor Co. and Sony Corp. halted production after Thursday's tremor but no major damage was reported.