The Japan meteorological agency issued a tsunami warning for a wave of up to one meter (3.2 feet). The warning was issued for a coastal area already torn apart by last month's tsunami.
Japan's NHK public television said those in areas where the tsunami warnings were issued should evacuate to higher ground.
Thursday's quake was 7.4-magnitude and hit 25 miles under the water, officials said. It struck off Japan's eastern coast about 60 miles from Sendai and 90 miles from Fukushima. It was about 215 miles from Tokyo, where buildings shoot for about a minute.
According to NHK, Tokyo Electric (TEPCO) says there are no additional problems at the Fukushima Dai-ichi nuclear power plant, where workers have been struggling to contain radiation since last month's quake and resulting tsunami.
Hundreds of aftershocks have shaken the northeast region devastated by the March 11 earthquake, but few have been stronger than 7.0