A powerful earthquake hit Japan's southernmost main island of Kyushu on Sunday, injuring at least 155 people, causing some houses to collapse and halting trains, media and officials said.

The meteorological agency issued tsunami warnings, but the advisories were lifted about an hour later.

Authorities, however, advised people to stay away from the coast and warned that aftershocks with magnitude of up to 6 were possible.

The focus of the magnitude 7.0 quake was off the western coast of Fukuoka Prefecture, about 900 km (550 miles) southwest of Tokyo on the island of Kyushu, and the depth was shallow, the meteorological agency said.

The quake was felt as far away as Seoul, the capital of South Korea. NHK showed footage of office buildings swaying in Fukuoka city, broken windows and cracks in pavements, and walls of buildings leaning to one side in Kyushu.

"It was so strong that I thought my house would collapse. I rushed to turn off the stove and evacuated. I felt uneasy because it was my first experience." Toshiyuki Yasukawa, an official in the town of Sue in Fukuoka, told NHK.

At least 155 people were injured in the earthquake, NHK said. It did not give details but several of the injured did not appear to need more than first aid.

A 26-year-old woman at an electric appliance store in Imari city in Saga prefecture cut her hand on shards of glass from a cracked TV screen, it said.

There were reports of broken water and gas mains, and high speed bullet trains and other trains and subways suspended operations. Bullet trains later resumed running, media said.

NHK showed footage of collapsed houses on Genkaijima, a small island not far from Fukuoka City on the main island of Kyushu.

Around 20 houses in Genkaijima have collapsed and 100 people evacuated to a community center on the island, NHK said, adding that 100 troops have been dispatched to the island to help with relief efforts.

"Aftershocks are continuing. We're all still nervous," said Shishida Yoshihisa, a school teacher in Genkaijima.

Kyodo said Fukuoka prefecture has asked for military helicopters to be sent to the island to transport injured people.

POWER OUTAGES

Fukuoka Airport suspended operations for checks but there were no reports of damage and it later reopened.

Some power outages were reported, but Kyushu Electric Power Co. said neither of its two nuclear power plants in Saga and Kagoshima prefectures were affected by the earthquake.

The earthquake, which hit at around 10:53 a.m. (0153 GMT) was recorded at magnitude 7.0 according to a technique similar to the Richter scale but adjusted for Japan's geological characteristics.

The quake registered a maximum intensity of lower six on the Japanese seismic scale of seven.

A quake measuring a lower six on the Japanese scale can make it difficult to stand. Sometimes, less quake resistant houses may collapse and gas pipes or water mains can be damaged.

"It shook from side to side, as if a big truck were passing by, and things fell off the shelves," said one woman in Fukuoka.

Officials gathered at the prime minister's official residence in Tokyo to monitor the situation, Kyodo said.

"I've received reports about the earthquake. Since there have been tsunami warnings, I have issued instructions to watch the situation closely," Prime Minister Junichiro Koizumi was quoted by NHK as telling reporters.

Katsuyuki Abe, a seismologist at the University of Tokyo, told NHK that an earthquake of magnitude 7 had hit the area about 300 years ago, but there were no records of other major quakes there since.

"This is a rare earthquake hitting the area," he said.

Earthquakes are common in Japan, one of the world's most seismically active areas. The country accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.

In October 2004, an earthquake with a magnitude of 6.8 struck the Niigata region in northern Japan, killing more than 40 people and injuring more than 3,000.

That was the deadliest quake since a magnitude 7.3 tremor hit the city of Kobe in 1995, killing more than 6,400.

PHOTO CAPTION

Rescue workers inspect a damaged house on tiny island of Genkai in Fukuoka after a powerful earthquake rattled southern Japan Sunday, March 20, 2005. (AP)