Photo/Illutration Mount Fuji as seen from the direction of Yamanashi Prefecture on March 26 (Wataru Sekita)

A revised hazard map for volcanic Mount Fuji in central Japan suggests the volume of lava flow from a major eruption would likely be double that of previous estimates.

The updated finding was put together by an organization made up of the three prefectures considered most at risk. They are Yamanashi, Shizuoka and Kanagawa.

The hazard map was first compiled in June 2004. Discussions on a revision got under way in fiscal 2018 in light of new research.

One finding was that the volume of lava flow from a Mount Fuji eruption would likely reach 1.3 billion cubic meters, not 700 million cubic meters as previously projected.

Seven cities and five towns in the three prefectures are now included in areas at risk of a lava flow. They include Sagamihara city in Kanagawa Prefecture, Shizuoka city and Otsuki in Yamanashi Prefecture.

The first hazard map was based on a study of Mount Fuji's eruptions over 32 million years. The revised hazard map pushed the date back to 56 million years ago. The range of possible craters was also expanded.

Under the revised hazard map, which also reflects topographical details, there are now 27 municipalities at risk of a lava flow from the 3,776-meter peak. The volume of a possible pyroclastic flow rose about fourfold from the previous estimate of 2.4 million cubic meters to 10 million cubic meters.

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