Part of central Japan could suffer a magnitude 8.1 earthquake if a temblor occurs near the Itoi River-Shizuoka fault line, a government panel said in a report Friday.
The quake, if it happens, would be between magnitude 7.8 and 8.1, a subcommittee of the Earthquake Research Committee said, adding that its intensity on the Japanese intensity scale would be a maximum 7 in Matsumoto, 6 in Hotaka and 5 in Azumi, all in Nagano Prefecture.
The forecast supposes that the northern and central parts of the tectonic plate, stretching about 120 km, move simultaneously and that the focus of the quake is about 10 km below ground in the northern tip of the Gofukuji zone in Matsumoto.
The committee made its strength prediction by considering the movement of the fault line and the structure of the ground, saying this is the first such prediction in the world.
The panel predicted the maximum value of acceleration, which measures the strength of a quake, could be up to 2,041 gals, exceeding the 818 gals in the Great Hanshin Earthquake and the 1,584 gals in the Tottori Prefecture earthquake.
Both the Hanshin quake that devastated Kobe in January 1995 and left more than 6,400 dead and the Tottori quake in October, which injured about 50 people, were magnitude 7.3.
The panel had earlier said that areas around the fault line have a 14 percent likelihood of being hit by an magnitude 8 quake sometime in the next 30 years.
The committee intends to draw a nationwide map of possible quakes with their estimated strengths by the end of fiscal 2004, after calculating the likelihood of their occurrence near 98 active zones and ocean trenches near Japan.