Japan Meteorological Agency blows volcano eruption forecasts over 80% of the time


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.

  • altamaiz

    Volcanology is a rather new science tasked with attempting to understand a little understood area of geology. To put things into perspective, the concept of plate tectonics, directly relevant to volcanism, has only been generally accepted science for 30 years. The JMA is as good as any other association studying this field. What is important at this point in time is that the field continues to be studied. Since volcanic eruptions are so dangerous, any knowledge we gain in this field is really vital. That is why I dislike antithetical stories such as this that miss this point so badly.

    • phu

      In my opinion, the important thing to take away from this is that such “forecasts” should be presented for exactly what they are: Attempts to predict complex and poorly-understood phenomena that, based on current methods, have a significant chance of being incorrect.

      I’m not suggesting the study or effort should be abandoned; if anything, this is a great reason to give it more time and attention, to improve our understanding of the processes at work and attempt to build and refine more accurate predictive models.

  • rossdorn


    “Volcanology is a rather new science…”

    Stop insultiung our intelligence… Vulcanology is NOT a science. You know NOTHING!

    This only works in Japan, where the people have gotten used to live in fear.

    • phu

      You’re right; the rest of the world struts around confidently and suffers from absolutely no fearmongering from government or media.

      Back in the real world, though, volcanology is indeed a valid branch of geology. The fact that it can’t provide for perfect timetables of eruptions says nothing about its scientific validity, only its maturity; all fields start from a position of poor understanding. Scientific research is the process of creating and refining models that define the world around us; that necessarily means we start off not knowing how everything works.

      Not that you’re going to accept that, of course. I just figured I’d put it out there so no one else has to refute the basis of your strangely passionate (and ignorant) dismissal if they don’t feel like it.