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A government panel is warning of a “high possibility” that an earthquake the size of the 2011 Great East Japan Earthquake will strike the area south of Hokkaido within the next 30 years.
The Headquarters for Earthquake Research Promotion, announcing the first revision in 13 years of quake predictions along the Chishima trench, said Dec. 19 that heightened disaster preparations should be made because the area appears long overdue for a gigantic quake.
The panel said the possibility was between 7 and 40 percent of an earthquake with a magnitude exceeding 8.8 occurring in an offshore focus area extending from Tokachi in south-central Hokkaido to Etorofu, one of the four islands making up the disputed Northern Territories.
The panel said quakes of that scale have stricken the area at average intervals of 340 to 380 years, with the most recent one believed to have hit about 400 years ago. Panel members said the end of the average cycle had already been exceeded.