A magnitude 6.9 quake struck off Miyazaki Prefecture, southern Japan, on Monday evening local time. Tsunami have already reached parts of Miyazaki and Kochi prefectures.

The magnitude 6.9 quake occurred in Miyazaki Prefecture, and in the hardest-hit areas had an intensity of lower 5 on the Japanese scale of 0 to 7.

The Japan Meteorological Agency has issued a tsunami advisory for Miyazaki and Kochi prefectures.

Tsunami have already reached the regions. In Miyazaki, 20-centimeter tsunami were seen, while Kochi reported 10-centimeter tsunami.

Officials are urging people to stay away from coastal areas.

The agency says an expert panel is investigating possible links between the strong tremor and a megaquake that is expected to strike the Nankai Trough in the seas off central through southwestern Japan.

The latest government estimate says that in the worst-case scenario, a Nankai Trough quake could claim more than 230,000 lives, and about 2 million buildings would be destroyed.