Feature Article

Is Mt. Fuji Still Only 10 Years Old!?
Understanding Volcanoes and Their Gifts
Through the "Cola" Analogy

The last time Mt. Fuji erupted was approximately 300 years ago, in the "Hōei Eruption." Because it has been silent for so long, many assume it will never erupt again — but Mr. Yoshimoto offered a unique lifecycle analogy to put it in perspective.

"A volcano's lifespan is about one million years. Mt. Fuji is only 100,000 years old — the equivalent of a 10-year-old child in human terms. When you think of it that way, 300 years without an eruption is really just Mt. Fuji holding its breath for a moment."

Mr. Yoshimoto also uses a cola analogy to explain how such different materials — "flowing lava" and "falling volcanic ash and pumice" — can come from the same magma.

This Is Where It Differs from Earthquakes!
The Reality of "Informed Fear" Disaster Preparedness on Mt. Fuji

Volcanic disaster preparedness is fundamentally different from earthquake preparedness, which deals with sudden, unpredictable events. While earthquake damage is primarily caused by shaking, volcanic eruptions produce lava flows, pyroclastic flows, mudflows, volcanic projectiles, volcanic gases, and more — according to the Cabinet Office, at least 16 separate hazard categories. Each of these hazards differs in temperature, speed (ranging from over 100 km/h to the pace of a walking human), and the distance they can reach.

Mt. Fuji adds another layer of complexity: eruptions can occur anywhere along a 28-kilometer span on both flanks, not just at the summit. This makes it impossible to simply copy the disaster preparedness plans of neighboring municipalities. Towns close to the mountain must prepare for projectiles and pyroclastic flows; towns farther away must think about lava flows and volcanic ash. Understanding which hazards apply to your specific location is essential.

"That's precisely why it's important not to panic or flee all at once, but to understand and 'fear correctly,'" says Mr. Yoshimoto. Just as understanding how a virus works and how to protect yourself expanded people's options during the pandemic, knowing your specific hazards allows you to evacuate calmly and effectively.

Making a habit of staying informed through real-time data tools like "Imafuji" — checking what's happening on the mountain right now — is itself a meaningful disaster preparedness action.

From Hands-On Teaching Materials to a Free Weekend Exhibition Hall!
Get Connected with Your Community —
Visit the Accessible Yamanashi Prefectural Mt. Fuji Research Institute

The Yamanashi Prefectural Mt. Fuji Research Institute studies Mt. Fuji's volcanic activity and natural environment day and night. While "research institute" might conjure images of a closed-off, strictly academic facility, it is in fact deeply committed to public outreach and education — helping local residents and children feel a personal connection to Mt. Fuji.

Mr. Yoshimoto's passion for children's education stems from a personal experience. "When I was in elementary school, a teacher was always in the science room — no matter what question I had, they always gave me a hint or an answer. That made learning fun and sparked my love of science. I want today's children to experience that same joy of having an adult nearby who can answer their questions."

As a result, the institute actively hosts field trips, volcanic lectures, and hands-on experiment classes for local elementary school students. One standout example is their original "experiment kit" for 6th-grade elementary and 1st-year junior high students studying volcanology. Using 3D topographic models, students are asked: "Lava flows downward, just like water — so if it erupted here, where would it flow?" and then pour liquids themselves to find out. Teachers report that students love it because "they can think through it and understand it themselves."

And perhaps most surprisingly — it's not widely known that the Yamanashi Prefectural Mt. Fuji Research Institute is open to the general public free of charge, including on weekends. Inside, you'll find an abundance of handcrafted displays painstakingly created by resident researchers specializing in birds, deer, volcanology, and more — working together with the education staff.

"I don't just want people to look — I want them to drop by casually, see and touch things in person, and feel what Mt. Fuji is really like. It would make me so happy if that made them fall in love with Mt. Fuji even more," says Mr. Yoshimoto. Come experience up close how real researchers keep watch over Mt. Fuji — this hidden "wonderland of knowledge" in the Fuji area is waiting for you.