The government released its annual update to Japan's earthquake probability map on Tuesday, indicating an increased likelihood of strong earthquakes occurring within the next 30 years across a wide area of the Pacific coast including parts of Hokkaido.

The map showed a sharp increase in the probability of a powerful earthquake, measuring lower 6 or stronger on the Japanese seismic intensity scale of 7, in Kushiro, Hokkaido, in the next 30 years, jumping 22 percentage points to 69 percent.

The sharp rise reflected research suggesting major earthquakes accompanying massive tsunami have repeatedly occurred along Chishima Trench, off eastern Hokkaido, in the past.