Less than 20 percent of volcanic eruption forecasts by the Meteorological Agency are accurate, the agency’s own data show.
According to the figures obtained Saturday, the agency has issued 21 eruption warnings for nine volcanos nationwide since December 2007, but got only four of them right.
Officials at the agency’s volcano division conceded that, despite the four successful forecasts, they remain unable to predict the exact location and duration of such events. Some experts attributed the findings to the difficulty of predicting near-term eruptions.
There are 110 active volcanos across Japan, and alert levels have been raised to warn of possible explosions for 10 of them since the warning system was introduced at the end of 2007. The agency’s data cover nine of those mountains; Sakurajima in Kagoshima Prefecture is excluded because it erupts with greater frequency.
Among the nine, one of two eruption forecasts proved accurate for Mount Meakan in Hokkaido, both forecasts for Mount Asama, which lies between Gunma and Nagano prefectures, and 1 in 4 for the Kirishima mountain range straddling the prefectural border between Miyazaki and Kagoshima.
The agency has never successfully predicted eruptions for the other six mountains. This includes the Mount Ontake blast on Sept. 27, the deadliest in Japan since the end of World War II.