A strong earthquake has hit Japan's northernmost main island of Hokkaido, but there are no immediate reports of injuries or damage.

The quake shook a wide area of the southwestern part of Hokkaido.

The Japan Meteorological Agency says the quake hit Thursday evening at a depth of 30 kilometers (19 miles) and measured a preliminary magnitude of 5.7. It says no tsunami is expected.

Public broadcaster NHK showed images that appeared to indicate a temporary blackout in one community.

NHK warned about possible landslides. It said nuclear plants in the area were being checked but no abnormal radiation readings were reported.