Tokyo - An earthquake with a preliminary magnitude of 6.7 struck off the Pacific coast of northern Japan early Thursday, Japanese and U.S. seismologists reported.

The Japan Meteorological Agency warned that a tsunami about one-half meter (19.5 inches) could be generated by the temblor, but there was no immediate report of damage or injuries.

The quake struck shortly before 7 a.m. (6 p.m. Wednesday ET) and was centered 530 kilometers (330 miles) north-northeast of Tokyo. The epicenter was off the northern prefecture of Iwate, about 175 kilometers (109 miles) north of where the magnitude 9 quake that devastated northern Japan struck in March.