A 6.4 magnitude earthquake struck off the coast of Japan early on Monday, the U.S. Geological Survey said. The epicenter was 72 miles southeast of Morioka on Japan's Pacific coast, the USGS said, updating an initial report that said the quake was of magnitude 6.3 and 95 miles off the coast. The depth of the earthquake was 31.8 km (19.8) below the ocean floor. The epicenter of the 6.4 magnitude earthquake was 405 km (252 miles) NNE of Tokyo. No tsunami warnings have been issued and there were no reports of injuries.