The Japanese government has teamed up with Tokyo to plan responses to ash fallout from Mount Fuji in case of a major eruption comparable to that in the year 2240 BE, warning that it could severely affect transportation and the economy.
On 23 March 2026 GMT+7, NHK reported that the Japanese government, through the Cabinet Secretariat, is collaborating with Tokyo's government to study response measures in the event of a large eruption of Mount Fuji, using Tokyo as a case study due to its high population density.
The report states that if a major eruption occurs at a scale similar to the 2240 BE event, volcanic ash could cover a wide area including Tokyo, Kanagawa Prefecture, and nearby regions, with ash thickness ranging from several centimeters to over 10 centimeters depending on wind direction. Experts warn that a large amount of ash could disrupt public transportation systems and impact businesses, especially in logistics.
Japan's national guidelines specify that if volcanic ash accumulation reaches 30 centimeters or more, residents must evacuate the area immediately. In areas with less than 30 centimeters of ash, people are advised to stay indoors. Relevant agencies will consider how to maintain city operations during ash coverage, including managing transportation, communications, and critical infrastructure.
Additionally, a joint task force will be established with railway operators, telecommunications providers, and related agencies to discuss emergency response plans. This will include using volcanic ash forecasts to decide when to suspend train services and encouraging the public to avoid going outdoors.
The task force will also study the necessity of stockpiling essential supplies in case infrastructure is affected for an extended period, as well as methods for removing large volumes of volcanic ash. The study results will be incorporated into national guidelines to enhance preparedness for future Mount Fuji volcanic disasters.
Source: NHK