By Kimimasa Mayama
Genkaijima, Japan - Nearly 3 000 people took refuge at evacuation centres on Japan's southern main island of Kyushu on Monday, a day after a magnitude 7.0 earthquake struck, killing one and injuring about 500 people.
On Genkaijima, a small island off the northern coast of Kyushu and hardest hit by the quake, about 200 buildings were either destroyed or damaged, and roads were cracked and blocked in many areas by debris.
Most of the 700 residents of the hilly island fled to the main island and spent a sleepless night in gymnasiums used as evacuation centres.
"I could not sleep because I was so worried," said one Genkaijima resident, a man in his 40s.
"I wanted to stay on the island, but the aftershocks were getting so bad, I felt it was just too dangerous," he said, sitting up on his futon mattress.
The focus of Sunday's quake was shallow and off the western coast of Fukuoka Prefecture, about 900km south-west of Tokyo.
The Meteorological Agency said aftershocks up to 6 in magnitude were possible, and one of magnitude 4.2 hit at 6:17am (21h17 GMT).
Soldiers in camouflage fatigues carried out relief operations on Genkaijima while police and government officials wearing helmets toured the island to assess the damage.
"Having seen with my own eyes, it's much worse than what I saw from the aerial photographs and other information," Fukuoka Governor Wataru Aso told reporters after touring the island.
The narrow streets running between rows of tightly packed wooden houses on the island were littered with roof tiles, rocks from landslides and bricks from collapsed walls.
Many of the damaged houses were leaning, and the roofs of others had caved in.
In Fukuoka city, the prefectural capital, buildings swayed, roads cracked and broken glass from shattered windows fell on the streets during the quake. A 75-year-old woman in the city died from injuries after a cement-block wall collapsed on her, police said.
In some areas, water and gas mains broke and bullet trains and other railway services were temporarily halted.
About 500 people were treated for injuries throughout Kyushu, with five remaining in serious condition, Kyodo news agency said.
"I think we're in for a long ordeal. It will take some time for things to get back to normal," said Fukuoka mayor Hirotaro Yamasaki said.
Officials said the number of deaths and injuries could have been much worse. Some attributed the relatively small number of casualties to the timing of the earthquake.
"Given the damage in other places from quakes of similar strength, I think it was lower than one would expect," said a Fukuoka prefectural official.
The meteorological agency briefly issued tsunami warnings after the quake hit at about 10:53am (01h53 GMT) on Sunday, but the alerts were lifted about an hour later.
The earthquake recorded at magnitude 7.0 according to a technique similar to the Richter scale but adjusted for Japan's geological characteristics.
Seismologists said that an earthquake of magnitude 7.0 had hit the area about 300 years ago, but there were no records of other major quakes there since.
Earthquakes are common in Japan, one of the world's most seismically active areas where a tremor is recorded every five minutes. 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.