Tokyo: A strong earthquake jolted on Sunday the same area of northeastern Japan that was hit by a massive quake in March, but there was no sign of further damage along the coast or to the crippled Fukushima nuclear power plant, officials said.
The Japan Meteorological Agency lifted a tsunami alert for the region before noon after initially urging residents in the disaster area to stay clear of the coast.
The US Geological Survey estimated the magnitude of the earthquake at 7.0 and said it had occurred at a depth of 18 km (11 miles) off the northeastern coast of Japan just before 10 am local time.
Four months ago, the same area was hit by a massive earthquake and tsunami that left at least 21,000 dead and missing. The March 11 disaster cut power to the Fukushima power plant and triggered a radiation crisis.
"It started as a small side-way tremble, then it grew gradually stronger," said Nobuyuki Midorikawa, an official at Iwaki City, Fukushima prefecture.
"Having experienced that much devastation in March, this latest earthquake and tsunami alert made me feel we cannot let our guard down against tsunami," Midorikawa said.
Tokyo Electric Power said workers closest to the coast at the Fukushima power plant were briefly evacuated to higher ground before returning to work.
The utility said there was no immediate sign of further damage at the nuclear plant where workers have been struggling to keep an improvised cooling system operating to stabilize the reactors and control radiation. The cooling system was not interrupted by the quake, the company added.
Tokyo Electric said there was also no damage to the massive barge moored just offshore from the Fukushima nuclear power plant that has been used as a temporary storage depot for radiated water for any damage.
The March 11 earthquake that struck off the coast of northeastern Japan had a magnitude of 9.0 and caused a tsunami that caused extensive damage along the coast and measured about 14 meters at the Fukushima nuclear plant.
The resulting loss of power at the Fukushima nuclear plant took out cooling systems and caused fuel in three of the plant`s six reactors to melt down. Subsequent hydrogen explosions scattered radioactive debris over a wide area.
About 80,000 nearby residents have been forced to evacuate because of the radiation and Japan`s government has come under fire for its handling of the disaster, putting pressure on unpopular Prime Minister Naoto Kan to resign.
One concern has been the strength of the building supporting what remains of the No. 4 reactor at Fukushima, and a Tokyo Electric spokesman said the utility expects that the structure would hold up in an earthquake stronger than the one that struck Sunday.