Japan is one of the most volcanically active countries in the world, and Mount Fuji remains one of its most iconic and potentially dangerous volcanoes.
Although the last eruption of Mount Fuji was in 1707 during the Hoei eruption, Japanese authorities have stepped up efforts recently to prepare for a possible large‐scale eruption.
These preparations span government planning, public guidance, scientific simulations, infrastructure readiness, and community awareness.
Evacuation Planning and Guidelines
A panel of experts convened by Japan’s Cabinet Office has drafted detailed response plans and evacuation guidelines in the event of a major eruption of Mount Fuji. The region potentially affected includes Greater Tokyo and surrounding prefectures.
The guidelines are built around a four-tier (or four‐stage) system based on how much ashfall is expected. In areas projected to receive 30 centimeters or more of ash (Stage 4), evacuation is strongly advised, particularly because wooden structures may collapse under wet ash.
In zones with less ash accumulation, residents may be urged to shelter indoors or in evacuation centers.
The guidelines also specify thresholds at 3 centimeters and 30 centimeters of ash, with tailored responses for each level.
If ash falls reach 3 centimeters or more but remain under 30 centimeters, the advice is generally to stay at home, adapt daily life accordingly, and be ready for disruptions. If ash exceeds 30 centimeters, evacuation becomes more likely.
Authorities are also prioritizing evacuation routes in zones expected to be worst affected. This includes planning how to move people safely from danger zones, determining where evacuation centers should be established, and identifying which roads need to be kept clear.
Emergency Supplies, Shelter and Infrastructure Readiness
Preparing for a major eruption entails more than evacuation plans. The expert panel has emphasized that households and municipalities should maintain emergency supplies like food, water, masks, goggles, and other essentials sufficient for at least two weeks.
Stockpiling such supplies is considered critical because ashfall can disrupt transportation, supply chains, and services.
Municipalities are also preparing shelters and evacuation centers. Many large buildings such as school gyms are often used as evacuation sites, but they may suffer damage from ashfall.
Authorities are assessing these structures for safety under ash load and making plans for which centers can operate under severe ash conditions.
In addition, infrastructure planning includes how to manage power outages, road blockages, water supply deterioration, and disruptions to communications.
Wet ash poses hazards to electrical lines and vehicles. Authorities have begun designating which roads will receive priority in ash removal, and which facilities (e.g. hospitals, governmental offices) must be kept accessible.
Simulations and Technological Tools
Japan is using simulations and advanced technologies to prepare both authorities and the public for what a large eruption might look like. One recent measure is an AI‐generated video released by the Tokyo Metropolitan Government on Volcanic Disaster Preparedness Day.
The video simulates the effects of an eruption, showing how ash could reach Tokyo within a few hours, how infrastructure might be paralyzed, and how daily life could be severely disrupted.
The goal is not to spread panic but to give citizens a vivid sense of what might happen and what preparations are needed.
Scientific modeling has also been used to estimate the volume of ash that might be produced in worst-case scenarios.
Authorities estimate ash deposits in certain regions and impact zones for transport, buildings, and utilities. These models help in defining the staging (Stage 1‐4) and determining zones for evacuation or sheltering.
Public Awareness
Besides government‐level readiness, public awareness campaigns are underway. Residents are being told to prepare in advance, both in terms of supplies and knowledge.
Families are encouraged to keep basic items, food, water, masks, first aid kits, ready in case ashfall or other disruptions make it difficult to leave the home or get supplies.
People in regions likely to be affected are also being educated about when to stay indoors and when evacuation is necessary, depending on ash levels.
Advice includes how to protect one’s health (e.g. wearing masks or goggles), what to do to keep building roofs clear of ash, and which structures may be unsafe under heavy ash weight.
Another important part of community preparedness is ensuring that local governments have hazard maps, evacuation timelines, and coordination with regional and national agencies.
This means local agencies must know routes, centers, and resources in advance so that if things escalate, responses can be swift.
Challenges and Uncertainties
Despite growing preparation measures, there remain serious challenges. Evacuating large densely populated areas around Tokyo may be impractical; some authorities believe that sheltering in place in many cases will be more realistic than mass evacuation.
Another issue is the sheer scale of ash production in severe scenarios. Some simulations suggest that hundreds of millions of cubic meters of ash could fall over large areas.
Removing, storing, and disposing of that ash poses logistical, environmental, and financial difficulties. Many jurisdictions do not yet have sufficient public space to store the removed ash.
Communication and public response behavior are also uncertain. Even when guidelines and warnings are issued, persuading large populations to follow them correctly (wear protective equipment, prepare supplies, avoid panic) can be difficult.
Simulations and awareness videos might be helpful, but the actual behavior unfolding under crisis may vary.
