By Minami Funakoshi and Kaori Kaneko
TOKYO (Reuters) - The desperate search for survivors intensified on Sunday in the splintered remains of buildings destroyed by Japan's deadly earthquake and authorities ordered nearly a quarter of a million people from their homes amid fears of further quakes.
A 7.3 magnitude tremor struck early on Saturday morning, killing at least 32 people, injuring about a thousand more and causing widespread damage to houses, roads and bridges.
It was the second major quake to hit Kumamoto province on the island of Kyushu in just over 24 hours. The first, late on Thursday, killed nine people.
Rescuers on Sunday searched for dozens of people feared trapped or buried alive, while survivors queued for scarce supplies of food and water.
In the village of Minami Aso, eight people remain "out of contact", said public broadcaster NHK. Rescuers pulled 10 students out of a collapsed university apartment in the town of Minami on Saturday.
Overnight, rescuers digging with their bare hands dragged some elderly survivors, still in their pyjamas, out of the rubble and onto makeshift stretchers made of tatami mats.
Prime Minister Shinzo Abe said the United States had offered to send in troops to help, but Japan was coping with the disaster.
"The Self Defense Force, police and fire-fighters have been working to rescue people but there are still missing people. The government will further deploy all possible means by expanding the troop size to 25,000," Abe told reporters.
Heavy rains fueled worries of more landslides and with fears of more quakes, thousands spent the night in evacuation centers. Firefighters handed out tarpaulins to residents so they could cover damaged roofs, but many homes were simply deserted.
The indiscriminate nature of the destruction saw some houses reduced to piles of splintered timber and smashed roof tiles while neighboring homes were left standing.
"I felt strong shaking at first, then I was thrown about like I was in a washing machine," said a Tokai University student who remains isolated in the village of Minamiaso.
About 422,000 households were without water and 100,000 without electricity, the government said.
NHK said around 240,000 people had received evacuation orders across the affected region amid fears of landslides.
NHK showed footage of people stranded after the fall of a bridge being rescued by helicopters.
Troops set up tents for evacuees and water trucks were being sent to the area.
The National Police Agency said 32 people had been confirmed dead in Saturday's quake. The government said about 190 of those injured were in a serious condition.
"RING OF FIRE"
Japan is on the seismically active "ring of fire" around the Pacific Ocean and has building codes aimed at helping structures withstand earthquakes.
A magnitude 9 quake in March 2011 north of Tokyo touched off a massive tsunami and nuclear meltdowns at Fukushima, contaminating water, food and air for miles around. Nearly 20,000 people were killed in the tsunami.
The epicenter of Saturday's quake was near the city of Kumamoto and measured at a shallow depth of 10 km (six miles), the United States Geological Survey (USGS) said. The shallower a quake, the more likely it is to cause damage.
However, no irregularities were reported at three nuclear power plants in the area, a senior government official said.
The city's 400-year-old Kumamoto Castle was badly damaged, with its walls breached after having withstood bombardment and fire in its four centuries of existence.
Bank of Japan Governor Haruhiko Kuroda, speaking at a G20 event in Washington, said it was too early to assess the economic impact but bank operations in Kumamoto were normal.
The USGS estimated there was a 72 percent likelihood of economic damage exceeding $10 billion, adding that it was too early to be specific. Major insurers are yet to release estimates.
Electronics giant Sony Corp said a plant producing image sensors for smartphone makers would remain closed while it assessed the damage from the quakes. One of its major customers is Apple which uses the sensors in iPhones.
Operations at Toyota Motor Corp and Nissan Motor Co Ltd were also disrupted.
The region's transport network suffered considerable damage with one tunnel caved in, a highway bridge damaged, roads cut or blocked by landslips and train services halted, media reported. Kumamoto airport was closed.
There have been 378 aftershocks of at least level 1 on the Japanese scale since Thursday's shock, NHK reported.
(Additional reporting by Linda Sieg, Elaine Lies, William Mallard, Shinichi Soashiro, Chris Gallagher, Kiyoshi Takenaka, Jon Herskovitz and Jack Kim in Seoul; Writing by Mike Collett-White and Michael Perry; Editing by Lincoln Feast)