A magnitude-6.8 earthquake struck off Japan's northeastern coast Friday, triggering a tsunami advisory that was later lifted. There were no immediate reports of damage or injuries in the temblor, which rattled the area devastated earlier this year by a massive quake and tsunami.
The 2:36 p.m. (0536 GMT) quake was centered about 185 miles (300 kilometers) northeast of Tokyo and at a depth of 12 miles (20 kilometers), slightly south of where the magnitude-9.0 temblor struck March 11, Japan's Meteorological Agency said.
The agency issued a tsunami advisory, predicting waves of 20 inches (50 centimeters) along the coast of Miyagi and Fukushima prefectures, where a nuclear plant crippled by March's quake-spawned tsunami is located. The agency lifted the advisory about 30 minutes later.
There were no abnormalities in key equipment at the Fukushima Dai-ichi nuclear power plant, said Chie Hosoda, an official with Tokyo Electric Power Co., the plant's operator. She said some of the plant's workers assigned to the coastal side of the facility temporarily retreated inside the building.
This was the first sizeable quake in the area in over a month. In the weeks following the huge March quake, Japan was frequently rocked by aftershocks, including several stronger than magnitude 7.0. Their frequency and size have declined considerably.
In Onagawa, about 210 miles (340 kilometers) north of Tokyo, town official Hironori Suzuki said there were no immediate reports of damage or injuries. There was no visible swelling of the ocean, he said.
"It was a rather big one, perhaps it was because we are still in a makeshift office," Suzuki told public broadcaster NHK. Suzuki said the town has urged all residents via community broadcast to stay away from the coast and evacuate to higher ground.
The quake caused buildings in Tokyo to sway. Bullet trains and several other local train services in the region were temporarily suspended for safety checks.
Just over 20,000 people died or disappeared across Japan's northeastern coastline after the March earthquake and tsunami. Some 100,000 others were forced to evacuate their homes because of the threat of radiation from the crippled Fukushima Dai-ichi nuclear plant.
March's tsunami destroyed cooling systems at that plant, sending its reactors to core meltdowns that caused massive amount of radiation to leak out of the complex. The radiation leaking has since dramatically declined.
The government has since ordered nuclear plant operators to take additional safety measures in case of a major quake and tsunami.