Japan's Meteorological Agency says the quake hit at 10:36 p.m. PT and took place at a depth of 24 miles.
The earthquake was centered slightly south of where a massive magnitude 9.0 temblor struck on March 11.
The agency issued a tsunami advisory, predicting waves of 50 centimeters along the coast of Miyagi and Fukushima prefectures, where nuclear reactors were crippled in the March quake.
In Tokyo, buildings swayed only mildly. So far there are no reports of damage or injuries.
DEVELOPING- We will provide more details as they become available.
The Associated Press contributed to this story.