A moderate earthquake measuring 5.9 on the Richter scale hit sea off Japan's Fukushima prefecture on the Honshu island Sunday, said Japan Meteorological Agency(JMA).
The epicentre of the temblor, which struck at 11.04 p.m. (local time), was initially determined at 37.1 degrees north latitude, 141.3 degrees east longitude with a depth of 50 km, Xinhua reported.
Though tremors were felt in Tokyo, no alert for tsunami was issued.