This is the second in a series of investigative reports from the Chunichi Shimbun about how figures for the probability of a Nankai Trough earthquake were manipulated for a government expert panel report released in February 2018.
Seismologists in a subcommittee of a government panel on earthquakes had been critical of a special calculation method used only for a Nankai Trough earthquake, and minutes of discussions revealed the skepticism they had from the start.
By using the method, called the “time-predictable model,” the probability of a huge earthquake striking the region within the next 30 years was assessed to be up to 80 percent. But the figure would be lowered to 20 percent if a different method used for all other quakes in Japan was applied. The time-predictable model therefore was considered unreliable by seismologists at a subcommittee on ocean-trench quakes under the government’s Earthquake Research Committee.