Image via WikipediaTOKYO – Japan was rattled by a magnitude-7.4 aftershock Thursday night nearly a month after a devastating earthquake and tsunami flattened the northeastern coast.The strongest aftershock since the day of the magnitude-9.0 megaquake was a fresh blow to victims of that March 11 quake and subsequent tsunami that killed some 25,000 people, tore apart hundreds of thousands of homes and has sparked an ongoing crisis at a nuclear power plant.
Damage and injuries from the aftershock were not immediately clear. The Japan meteorological agency briefly issued another tsunami warning Thursday night, but later canceled it.
Officials at the tsunami-ravaged Fukushima Dai-ichi nuclear plant said there was no immediate sign of new problems caused by the aftershock. Japan's nuclear safety agency says workers there have retreated to a quake-resistant shelter in the complex. No one there was injured.
Officials say Thursday's aftershock hit 30 miles (50 kilometers) under the water and off the coast of Miyagi prefecture. The quake that preceded last month's tsunami was a 9.0-magnitude. The U.S. Geological Survey in Golden, Colo., later downgraded Thursday's quake to 7.1.
Japan Meteorological Agency said the quake was a magnitude 7.4. The U.S. Geological Survey said it was 7.1.
Workers evacuated the Fukushima Daiichi nuclear plant following the quake, the Tokyo Electric Power Company said. The company said it has communication with the plant and the power is still on there. There were no immediate reports of damage, it said.
The quake's epicenter was off the coast of Miyagi in northeastern Japan, the Japan Meteorological Agency said.
The U.S. Geological Survey said the quake was centered 41 miles (66 kilometers) from Sendai -- one of the areas worst hit by last month's 9.0-magnitude quake -- and 73 miles (118 kilometers) from Fukushima, where a crisis has been under way at the nuclear plant since last month's tsunami.
Public broadcaster NHK reported a tsunami warning for Miyagi prefecture, saying people in that area should evacuate away from the shore to a safe place.
NHK also reported tsunami advisories for the Pacific coast of Aomori Prefecture, and for the Iwate, Fukushima, and Ibaraki Prefectures.
