( CNN ) -- A strong earthquake with a magnitude of 6.8 struck off the coast of Japan on Sunday , the U.S. Geological Survey reported . The earthquake hit 468 kilometers ( 302 miles ) south-southwest of Tokyo at a depth of 348 kilometers , according to the USGS . There were no immediate reports of injuries or damage . The Pacific Tsunami Warning Center did not issue a tsunami warning . The USGS gave the quake a preliminary magnitude of 7.0 before downgrading it to 6.8 . Ohio looks into quakes ' possible link to fracking . Japan lies along the Pacific `` ring of fire , '' an area of high seismic and volcanic activity stretching from New Zealand in the South Pacific up through Japan , across to Alaska and down the west coasts of North and South America . Last year , a devastating earthquake and tsunami hit northeastern Japan , leaving thousands of people dead or missing . The March 11 earthquake triggered powerful tsunami waves and sparked a nuclear crisis .
The earthquake occurred 468 km ( 302 mi ) south - southwest of Guam . There are no immediate reports of injuries or deaths . The Pacific Tsunami Warning Center did not issue a tsunami warning .