A major earthquake measuring 6.5 on the Richter Scale struck off the coast of eastern Japan on Monday, according to media reports.
The earthquake caused no apparent damage but the Japan Meteorological Agency declared a tsunami alert in Miyagi Prefecture.
The quake struck near the east coast of Honshu, said authorities.
Japan is struggling to cope with the aftermath of an earthquake and a tsunami that struck on March 11, leaving 18,000 people dead and thousands missing.