TOKYO — A strong earthquake with a preliminary magnitude of 6.9 has hit southwestern Japan, the country’s Meteorological Agency said Monday, while warning the public to stay away from coastal areas because of a tsunami threat.

A strong earthquake struck southwestern Japan, the U.S. Geological Survey said, prompting authorities to issue a tsunami advisory.

Japan is frequently hit by earthquakes because of its location along the “Ring of Fire,” an arc of volcanoes and fault lines in the Pacific Basin.