An earthquake of magnitude 7.3 struck Saturday morning off Japan's east coast, the US Geological Survey said. Japan's emergency agencies declared a tsunami warning for the region that includes the crippled Fukushima nuclear site.
Japan's Meteorological Agency raised a 1-meter (3-foot) tsunami warning for a long stretch of Japan's northeastern coast, including Fukushima. It put the magnitude of the quake at 7.1. The US Pacific Tsunami Warning Center did not post warnings for the rest of the Pacific.
There were no immediate reports of damage on land.
The quake hit at 2:10 a.m. Saturday Tokyo time (1710 GMT) about 290 kilometers (170 miles) off Fukushima. Japanese broadcaster NHK reported that Tokyo Electric Power Co., the operator of the Fukushima plant, ordered workers near the coast to move to higher ground.
The tremor was felt in Tokyo, some 300 miles (480 kilometers) away.
All but two of Japan's 50 reactors have been offline since the March 2011 magnitude-9.0 earthquake and ensuing tsunami triggered multiple meltdowns and massive radiation leaks at the Fukushima Dai-ichi nuclear power plant, about 250 kilometers (160 miles) northeast of Tokyo. About 19,000 people were killed.