An earthquake with a magnitude of 5.2 struck the north of Nagano Prefecture on Saturday morning, according to the Meteorological Agency. A tsunami warning was not issued.
The quake, which occurred at 10:29 a.m. at a depth of around 11 kilometers, registered a lower 5 on the Japanese seismic intensity scale of 7. It measured a lower 5 in the cities of Nagano and Omachi, as well as in the village of Ogawa.
No abnormalities were reported at the Kashiwazaki-Kariwa nuclear power plant in neighboring Kashiwazaki, Niigata Prefecture, where the quake registered a 2 on the Japanese scale, according to operator Tokyo Electric Power Company Holdings Inc.
There have been no reports of injury or property damage, prefectural and police officials said.