An earthquake with a preliminary magnitude of 5.5 jolted the Tokyo area on Friday, the Japan Meteorological Agency reported.
There were no immediate reports of damage and no tsunami alert was issued following the quake, which was centred in Ibaraki prefecture north of Tokyo, although some bullet trains were halted, public broadcaster NHK said.
Japan Atomic Power, operator of the Tokai No.2 nuclear power plant in Ibaraki prefecture, said there were no abnormalities at the single-reactor plant after the earthquake.
A Japan Atomic Power official said the plant has been shut for scheduled maintenance.
(Reporting by Yoko Kubota and Kiyoshi Takenaka; Editing by Edmund Klamann)