An earthquake with a preliminary magnitude of 5.1 has struck off Japan's eastern Ibaraki prefecture, according to the Japan Meteorological Agency (JMA).
The quake originated in the Pacific at 4.13 am local time Thursday (1913GMT Wednesday) at a depth of about 50 kilometers (31 miles).
No tsunami warning was issued, the Tokyo-based Kyodo News reported.
There were no reports of casualties or infrastructural losses.
