An earthquake with a preliminary magnitude of 5.5 jolted the southern part of Ibaraki Prefecture on Sunday morning, the Japan Meteorological Agency said.
No abnormalities have been reported at nuclear facilities in the prefecture. No tsunami warning was issued.
The 7:38 a.m. quake registered lower 5 on the Japanese seismic intensity scale of 7 in Chikusei in Ibaraki and 4 in other areas in the prefecture, as well as some areas in Tochigi, Saitama and Chiba prefectures and in Tokyo.
The focus was about 70 km underground in the southern part of Ibaraki Prefecture, the agency said.