TOKYO -- An earthquake with a preliminary magnitude of 6.4 struck off the west coast of Japan's Shikoku island on Wednesday night, a weather agency said.

The temblor occurred at 11:14 pm local time, measuring lower 6 on the Japanese seismic intensity scale of 7 in parts of Ehime and Kochi prefectures, said the Japan Meteorological Agency (JMA).

The epicenter was located off Ehime Prefecture at a depth of 50 km in the Bungo Channel, a straight separating the islands of Kyushu and Shikoku.

With no tsunami threat from the earthquake, it was not immediately clear if the powerful quake had caused injuries or damage.