While the nation continues to step up its defense against earthquakes and tsunamis through the lessons learned from the 1995 Great Hanshin Earthquake and the 2011 Great East Japan Earthquake, it hasn’t made much progress in devising plans to protect people during volcanic eruptions — which could have equally or even more disastrous effects on people’s lives. The national and local governments need to urgently compile practical plans for responses, including mass evacuations, in the event of a large-scale eruption.

Of the nation’s 110 volcanoes categorized as “active,” 47 — including Mount Fuji — are under constant surveillance via seismometers and video cameras for possible eruptions. There are communities not far from many of these volcanoes, including tourism destinations for climbers and hot spring resorts.

Municipalities located near the volcanoes under surveillance are being urged to set up disaster-response councils comprising members from their own and other local governments as well as the central government, create hazard maps showing areas that may be affected by eruptions and draw up evacuation plans.

In reality, these efforts lag because many of the municipalities have little or no experience with large-scale volcanic eruptions.

Earlier this month, a council of officials from Kanagawa, Yamanashi and Shizuoka prefectures and the central government compiled an evacuation plan for areas expected to be affected by a large-scale eruption of Mount Fuji, which last erupted in 1707. The plan anticipates evacuating 470,000 people from areas where at least 30 cm of volcanic ash is expected to accumulate.

A total of 750,000 people in Shizuoka and Yamanashi prefectures live within range of forecast lava and pyroclastic flows. The plan estimates that depending on the direction of the flows, up to 200,000 people would need to evacuate these areas.

Still preliminary, the plan merely shows how many people would need to evacuate in the event of a large-scale eruption, when they need to start evacuating, and where they should go. More specifics need to be decided to ensure the safe and orderly evacuation of such a huge number of people.

It is obvious that massive traffic jams would develop if many of these people used their cars to flee. So, public transportation, including buses, would need to be mobilized to evacuate as many people as possible. It must be decided who will oversee the evacuation of tourists. A prioritized list of areas should be drawn up to allow an orderly evacuation in stages.

The evacuation plan for a Mount Fuji eruption will serve as a model that other municipalities located near volcanoes could emulate. The three prefectures must strive to come up with as practical a plan as possible. Myriad questions remain that must be answered and training exercises need to be carried out.

The central government should oversee local authorities’ efforts, guiding them in drawing up evacuation plans, dispatching experts who have firsthand experience and knowledge of eruptions, and coordinating with them on how to prepare for evacuation when signs of an imminent eruption are detected. In the event of a large-scale eruption, emergency headquarters should be established both in Tokyo and in the affected local areas.

Because it is not yet entirely clear what the central government should do in the event of an eruption, it should draw up an emergency-response plan that specifies its role and responses. The effects of volcanic ash from a large-scale eruption of Mount Fuji, for example, could extend beyond neighboring prefectures and impact much wider swaths of the country, including Tokyo.

Depending on the amount of ash that falls, the disaster could force the closure of airports, expressways and train services; cause power outages; and contaminate water supplies, resulting in serious problems for urban residents. Damage to farmland could disrupt food supplies. The central government’s emergency response plan should also address these issues.

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