An earthquake with a preliminary magnitude of 6.1 struck off Aomori Prefecture in northeastern Japan on Tuesday evening, possibly causing slight fluctuations in coastal waters, the Japan Meteorological Agency said.

The 6:18 p.m. quake registered 4 in parts of Hokkaido, Aomori and Iwate prefectures on the Japanese seismic intensity scale of 7. The temblor originated off Aomori's eastern coast at a depth of around 20 kilometers.

Any fluctuations on the surface of the sea caused by the quake are unlikely to cause harm or damage, according to the agency.