A strong earthquake has struck off Japan's east coast but caused no apparent damage.

The Japan Meteorological Agency said an undersea earthquake with a preliminary magnitude of 6.5 hit Friday morning at a depth of about 10 kilometers. It did not issue a tsunami warning. The agency said there may be slight changes in coastal sea levels, but not enough to cause any damage.

The U.S. Geological Survey, which measured the magnitude at 6.3, said the quake hit about 150 kilometers (90 miles) off the coast of Chiba prefecture, a suburb of Tokyo. The epicenter was about 230 kilometers (140 miles) southeast of the Japanese capital. It caused minor shaking in the Tokyo region, though many said they didn't feel it.