June 23, 2026
TOKYO – The government’s Headquarters for Volcano Research Promotion has decided to rank the country’s active volcanoes individually based on their future eruption risks.
A new subcommittee, which will be composed of experts to assess eruption risks and other factors, will be established by the summer. By providing rankings grounded in scientific evidence, the headquarters aims to strengthen observation systems and raise public awareness of disaster management during and after volcanic eruptions.
The headquarters was launched in April 2024 to serve as a command center for the centralized management of volcano observation and research. It is currently drafting its comprehensive basic policy, which will outline observation and research strategies for the next 10 years. The headquarters has decided to include the establishment of the new subcommittee and the risk ranking system in this policy.
The new subcommittee is expected to consist of about a dozen members, including volcanologists. They will assess each volcano’s probability of erupting over the coming decades based on scientific evidence, such as observational data on crustal deformation, the scale and style of past eruptions and the condition of magma. The headquarters plans to complete the rankings over a period of about five years, hoping that local governments will reflect the results in their regional disaster management plans.
Japan’s 111 active volcanoes are currently categorized into groups based on definitions such as “volcanoes that have erupted within about the past 10,000 years.”
However, recent studies have identified other mountains that could potentially be active. The new subcommittee plans to utilize the latest findings to select additional active volcanoes to be included in the ranking process. Specifically, Mt. Mitsudake in Nikko, Tochigi Prefecture, and Yokoatejima Island in the Tokara Islands in Kagoshima Prefecture are likely to be considered.
Regarding natural disaster risk assessments, the government’s Headquarters for Earthquake Research Promotion, which was established following the 1995 Great Hanshin Earthquake, has evaluated the scale and probability of trench-type earthquakes and those caused by active faults. These evaluations have been utilized in local disaster management plans.
The volcano headquarters’ ranking of active volcanoes is likewise expected to be used by local governments in drafting evacuation plans for residents and setting up off-limits zones during eruptions.
“Compared to earthquakes, Japan is lagging behind in its preparedness for volcanic eruptions,” said Prof. Toshitsugu Fujii, professor emeritus at the University of Tokyo, who is involved in drafting the headquarters’ basic policy. “The characteristics of volcanoes are not uniform; the expected scale of an eruption and the course of events following it vary widely. We need to implement tailored measures for each active volcano, and this ranking system will be the starting point.”