TOKYO (December 7, 2012)--Several people along Japan's northeastern coast were reported injured after a strong earthquake hit off the same Japanese coast that was devastated by last year's massive quake and tsunami.
The quake generated small waves, but there were no reports of heavy damage.
Buildings in Tokyo and elsewhere swayed for several minutes.
Japan's Meteorological Agency said the quake had a preliminary magnitude of 7.3.
The epicenter was 150 miles offshore, and more than six miles below the seabed.
The agency said there were repeated, smaller aftershocks.
After the quake, authorities warned that a tsunami as high as six feet could hit, and people ran for higher ground, but the tsunami warning has been canceled.
Japan has barely begun to rebuild from last year's magnitude-9.0 quake, which triggered a tsunami that ravaged dozens of coastal communities.
Residents had a warning, shortly before the quake Friday.
Public television broadcaster NHK broke off regular programming to warn that a strong quake was due to hit.
The country's Meteorological Agency has an early warning system that uses data from seismographs scattered across the country.
It allows the agency to provide advance warning of the estimated intensity and timing of a major quake.
According to an agency official, Friday’s warning was issued six minutes before the quake struck.
After the warning was broadcast, an announcer repeatedly urged everyone living near the coast to flee to higher ground.