TOKYO, April 18 (Xinhua) -- An earthquake with a preliminary magnitude of 5 struck Japan's Nagano Prefecture on Friday night, with no tsunami threat, according to the country's weather agency.

The temblor occurred at 8:19 p.m. local time at a depth of 10 km, registering a seismic intensity of lower 5 on Japan's scale in the cities of Omachi, Chikuhoku Village, and Ogawa Village.

The Japan Meteorological Agency confirmed there is no tsunami risk associated with the quake.

Power outages were reported in parts of Ogawa Village, but no injuries were confirmed by local fire departments as of 9:00 p.m., according to local media.

The earthquake also affected transportation. JR East temporarily halted Hokuriku Shinkansen operations between Karuizawa and Itoigawa stations immediately after the quake. ■