A moderately strong earthquake has rattled the Tokyo region, but there are no immediate reports of damage or injuries.
The Japan Meteorological Agency (JMA) says the quake hit at midday on Sunday with a magnitude of 5.
Its epicentre was 40km underground in Ibaraki prefecture, northwest of Tokyo.
The JMA says there is no risk of tsunami from the quake.
Japan's nuclear regulator says a nuclear power plant in the area suspended operations while it checked for any problems.