Muscat: A strong earthquake with a preliminary magnitude of 6.8 has hit southwestern Japan, the country's Meteorological Agency said today. Tsunami advisories were issued for Miyazaki Prefecture, where the temblor was centered, in the southwestern island of Kyushu, as well as nearby Kochi Prefecture, shortly after the quake struck at 9:19 p.m. local time, according to the agency. According to Oman News Agency, the JMA urged the public to stay away from coastal waters. 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.