World Natural Heritage in Japan: Mt.Fuji

Mount Fuji, the mountain that captivates the world

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Thoughts on Mount Fuji (1)

A must-see for foreign climbers: Mount Fuji, the world’s envy

Amid the recent surge in inbound tourism to Japan, an increasing number of international hikers are visiting the revered peak of Mount Fuji, which is a designated World Cultural Heritage site.
Mount Fuji is more than just Japan’s tallest mountain; behind its majestic facade lies a profound narrative woven from a spectacular natural history and the spiritual culture of the Japanese people.
However, despite its allure, a growing number of people are attempting to climb it without adequate knowledge or preparation, leading to an increase in accidents.

Table of Contents

This article delves into the multifaceted aspects of Mount Fuji to help you enjoy it safely. We provide a comprehensive overview, from the geological history of how Mount Fuji came to be, to the deep-seated reverence the Japanese people have held for it since ancient times, and even disaster preparedness for the future. Additionally, we will explain the specific dangers of high-altitude climbing and offer practical guidance for a safe ascent, ensuring all climbers can genuinely engage with Mount Fuji.

The Epic History of Mount Fuji: How It Came to Be

Mount Fuji was not formed by a single volcanic event.
Its elegant conical shape was created through the layered activities of multiple volcanoes, which underwent cycles of destruction and renewal.
Understanding this multi-layered formation process is essential to grasping the root of Mount Fuji’s beauty.

Three Volcanoes That Built the Famous Mount Fuji

The formation of Mount Fuji can be divided into three major volcanic periods.
The first stage began approximately 700,000 years ago with the activity of the Komitake Volcano.
The summit of this volcano is exposed at an altitude of 2,300 meters on the northern slope of the present-day Mount Fuji, around the 5th station.
This period coincided with the active phases of nearby volcanoes such as Mount Ashitaka and Mount Hakone.

After the Komitake Volcano became dormant, a new active period began approximately 100,000 years ago with the Ko-Fuji Volcano (Old Fuji).
The Ko-Fuji Volcano was characterized by explosive eruptions, spewing out vast quantities of volcanic ash, scoria, and lava.
The ash from this period was so widespread that it formed a major part of the Kanto Loam Layer.
Through repeated eruptions and collapses, this volcano built a massive mountain body that reached an altitude of 3,000 meters.

Then, starting around 10,000 years ago, the Shin-Fuji Volcano (New Fuji) began its activity, shaping the Mount Fuji we know today.
Repeated eruptions from the Shin-Fuji Volcano covered the scars left by the collapse of Ko-Fuji, completing the beautiful, conical mountain recognized worldwide.
The iconic beauty of Mount Fuji is, in fact, built upon a history of violent volcanic activity involving destruction and renewal, showing that its graceful appearance and its potential danger as an active volcano are two sides of the same coin.

The Eruptive History of Mount Fuji: The Jogan and Hoei Eruptions

Since recorded history, Mount Fuji has erupted many times, with records preserved in ancient documents and sediment layers.
Among them, the Jogan eruption during the Heian period and the Hoei eruption during the Edo period are two major events that are indispensable to the history of Mount Fuji.
These eruptions are not merely historical events; they continue to directly influence the current landscape of Mount Fuji and people’s awareness of disaster preparedness.

The Great Jogan Eruption (864 AD) occurred five years after the Jogan Earthquake.
A massive amount of lava flowed from a fissure on the northern slope, splitting a lake in two. This lava flow covered a wide area, and a new forest grew over it, eventually becoming what is now known as the Aokigahara Jukai (Sea of Trees).
Today’s mystical forest is a landscape born from a past cataclysm.

The Great Hoei Eruption (1707 AD) was an explosive eruption second only in scale to the Jogan eruption.
It occurred on the southeastern flank about 49 days after the Hoei Tokai and Nankai earthquakes of the previous year and continued intermittently for 16 days.
The volcanic plumes reached a height of 15 kilometers, and volcanic ash, carried by prevailing westerly winds, fell as far as the city of Edo (modern-day Tokyo).
This eruption created three or more craters on the southeastern flank of Mount Fuji, forming Hoeizan, a distinctive peak on the side of the main volcano.

Although the chemical composition of the ejecta from the Jogan and Hoei eruptions was similar basalt, the eruption styles were vastly different.
The Jogan eruption was dominated by lava flows, while the Hoei eruption was explosive.
This is thought to be due to differences in the dehydration process of the magma underground and the eruption mechanisms.
The fact that past major eruptions shaped today’s landscape and ecosystem and that widespread ash damage formed the basis for modern hazard maps and disaster plans demonstrates how Mount Fuji has shifted from being a “religious object” to a “disaster preparedness object” based on scientific observation.

Mount Fuji Eruption History Timeline

By organizing the history of Mount Fuji’s eruptions chronologically, it becomes clear that its activity has been frequent even in recorded history.
In particular, the Heian period saw a high frequency of eruptions recorded in historical documents.

Date	Event / Notable Fact
Approx. 100,000+ years ago	Komitake Volcano begins its activity.
Approx. 100,000–10,000 years ago	Ko-Fuji Volcano active, with repeated explosive eruptions.
Approx. 10,000 years ago–Present	Shin-Fuji Volcano becomes active, forming the current conical shape of Mount Fuji.
781 AD	Eruption recorded in Shoku Nihongi: “Ash falls on the foothills, withering tree leaves.”
800 AD	Enryaku Eruption. The Ashigara Road is blocked, and the Hakone Road is opened.
864 AD	Jogan Eruption. A lava flow from the northern slope forms the Aokigahara Jukai.
937 AD	Eruption. The Takamaruo-Hinokimaruo lava flow dams Lake Yamanaka.
999 AD	Eruption recorded in Honchō Seiki: “The mountain of Fujiyama burns.”
1083 AD	Eruption recorded in Fusō Ryakki: “Mount Fuji burns.”
1707 AD	Hoei Eruption. Explosive eruption from the southeastern flank, forming the Hoei Crater and Hoeizan.
1923 AD	Fumarolic activity is recorded.
1987 AD	A perceptible earthquake is felt near the summit.

A Symbol of Awe and Worship: The Special Reverence for Mount Fuji in Japan

Mount Fuji has long been an object of worship for the Japanese people, not only for its beauty but also for the terror of its active volcanic nature.
Facing the threat of eruptions, people believed that a god resided within Mount Fuji and approached it with both awe and respect.

A Faith to Appease Eruptions: Fujisan Hongū Sengen Taisha

In ancient Japan, people worshipped Mount Fuji as a sacred mountain from afar, feeling a sense of awe at its eruptions.
To appease the fear of these eruptions, the Sengen Shrine was founded to enshrine Mount Fuji as a god.
The Fujisan Hongū Sengen Taisha, in particular, is said to have been established at the base of Mount Fuji during the reign of Emperor Suinin and serves as the head shrine for over 1,300 Sengen shrines nationwide.

The main deity, Konohanasakuya-hime no Mikoto, is revered as a goddess who can avert disaster by fire, and also as a deity of safe childbirth and raising children.
The myth of her safely giving birth to an imperial prince in a fire led to her being worshipped as a fire-appeasing god and a water-controlling deity.
During periods of active volcanism, people would perform Yōhai (worshipping from a distance), offering prayers from afar to quell the eruptions.
This form of worship has changed in direct correspondence with the geological changes of Mount Fuji.

From Distant Worship to Ascetic Climbing: The Spread of Shugendō and Fuji-kō

As volcanic activity on Mount Fuji subsided in the late Heian period, it became a site for Shugendō – a syncretic spiritual practice – and climbing the mountain (Tōhai) for spiritual training became popular.
This shift indicates that Mount Fuji was no longer seen as merely an object of fear but as a sacred site for achieving enlightenment through rigorous training.

During the Edo period, faith in Mount Fuji spread widely among the common people, leading to the formation of religious groups known as Fuji-kō.
Members of Fuji-kō not only climbed Mount Fuji to pray for a peaceful afterlife but also built Fujizuka (miniature replicas of Mount Fuji) for those who could not make the actual climb, believing that ascending these mounds would grant the same blessings as climbing the real mountain.
These religious groups served a social function beyond their spiritual goals, fostering fellowship and recreation among their members.

Mount Fuji as a Source of Art

Mount Fuji has long inspired countless artists with its magnificent form.
The Man’yōshū, Japan’s oldest existing collection of poetry, contains verses about Mount Fuji, including a poem by Takahashi Mushimaro.
In the Tale of the Bamboo Cutter, Princess Kaguya gives the Emperor a potion of immortality, which the Emperor orders to be burned on the mountain closest to heaven.
This legend is said to be the origin of the name “Fuji” (which can be written with characters meaning “not two” or “immortal”).

During the Edo period, Mount Fuji was a frequent subject of ukiyo-e woodblock prints, as seen in Katsushika Hokusai’s Thirty-six Views of Mount Fuji and Utagawa Hiroshige’s The Fifty-three Stations of the Tōkaidō.
Its beautiful form became widely known both in Japan and abroad.
When Mount Fuji was registered as a World Cultural Heritage site in 2013, its intangible cultural values as a “religious object” and “source of art” were highly praised as having universal significance.

The Present and Future of Mount Fuji: Eruption Potential and Disaster Preparedness

Mount Fuji remains an active volcano. Its most recent eruption was the Hoei eruption in 1707, and it has been dormant since then. However, this period of calm will not last forever.

Mount Fuji as an Active Volcano: What Are the Chances of the Next Eruption?

Currently, Mount Fuji is at the lowest eruption alert level, Level 1 (“Be mindful that it is an active volcano”).
While there is no immediate cause for concern at this stage, it’s crucial not to be complacent.
Historical records show that Mount Fuji has erupted 100 times in the last 3,200 years, which, based on a simple calculation, averages out to one eruption approximately every 30 years.
The fact that it has not erupted for over 300 years since the Hoei eruption is a geologically long period of dormancy, suggesting that another eruption could occur at any time.

While 96% of the eruptions over the past 5,600 years were small to moderate in scale, there is no guarantee that the next eruption will be of the same magnitude.
The possibility of a large-scale eruption remains.
The current state of Mount Fuji is a delicate balance between reassurance and vigilance, and it is vital to be prepared for the day an eruption does occur.

Signs of Increased Activity and Alert Levels

The Japan Meteorological Agency monitors Mount Fuji’s volcanic activity 24/7.
Should any signs of an eruption be detected, the agency will promptly announce the appropriate eruption alert level.
Possible signs of increased activity include a cluster of perceptible earthquakes in the area or ground rumbling.

If the eruption alert level is raised, national and local governments will implement measures such as evacuation preparations and climbing restrictions.
This requires broad cooperation not only among local municipalities but also between prefectural and national governments.
This is because a potential eruption of Mount Fuji would not only produce lava flows but also cause widespread ashfall, which could affect major transportation networks and socioeconomic activities over a vast area.

Hazard Maps and Action Plans for Eruptions

Local governments around Mount Fuji have created hazard maps to minimize damage during an eruption.
These maps outline the potential spread of lava flows, mudflows, and volcanic ashfall and indicate what actions residents and tourists should take.

A report published by a Cabinet Office committee concluded that a full evacuation of residents is not realistic, given the potential for widespread ashfall over the Tokyo metropolitan area during a large-scale eruption.
Therefore, the basic policy recommends that people in ashfall areas continue to live in their homes, with a call to prepare at least a one-week supply of food and other essentials, and ideally a two-week supply.
This clearly shows that a Mount Fuji eruption is a wide-area disaster that would affect not just climbers and residents at the base of the mountain, but the entire social and economic fabric of Japan.

For Those Aiming for the 3,700m Summit: A Complete Safety Guide

While Mount Fuji is Japan’s tallest and most beautiful mountain, it presents a severe natural environment unique to its 3,776-meter altitude.
Given the increasing number of accidents, especially involving international hikers, knowledge and preparation for a safe climb are essential.

Why Accidents Happen on Mount Fuji: Causes and Countermeasures

The main causes of accidents on Mount Fuji are overconfidence in physical ability or skills, and a lack of knowledge or experience.
The increase in accidents involving international climbers is often attributed to a tendency for “casual climbing” – where the climb is an impromptu add-on to a trip – and a lack of understanding of Japanese hiking culture and rules.

The specific dangers to be aware of when climbing Mount Fuji:

Type of Danger	Main Cause and Background	Prevention and Countermeasures
Altitude Sickness	Decreased oxygen concentration with rising altitude, fatigue, dehydration, rapid changes in altitude.	Acclimatize at the 5th station for 1-2 hours before starting the ascent. Stay hydrated with frequent sips of water. Maintain a slow, steady pace and focus on deep breathing. Stay overnight at a mountain hut to let your body rest.
Hypothermia/Heatstroke	The summit has sub-zero temperatures. Exposure to wind and rain can cause a rapid drop in body temperature. Sunny days carry a risk of heatstroke due to direct sunlight.	Wear multiple layers of clothing, including moisture-wicking base layers, a fleece, and waterproof outerwear, to regulate body temperature. Change out of wet clothes. Wear a hat and frequently replenish fluids and electrolytes.
Falling Rocks	Loose rocks dislodged by increased hikers, or ground instability from melting snow or rain.	Walk on the inner (mountain side) of the trail. Avoid resting in areas with “Beware of Falling Rocks” signs. If you accidentally dislodge a rock, shout loudly to warn others.
Getting Lost	Misreading a trail fork in poor visibility. Getting separated from your group.	Check your route on a map and do not stray from the trail. Always stay with your group.

The 3,700m World: Unpredictable Weather and Effects on the Body

At 3,776 meters, Mount Fuji has an environment completely different from the lowlands.
The temperature drops by approximately 0.6°C for every 100 meters of altitude gain, meaning summit temperatures can be below freezing even in mid-summer.
Additionally, strong winds and sudden weather changes are common.

The most significant effect of this harsh environment on the human body is altitude sickness.
At high altitudes, the lower oxygen concentration can lead to headaches, nausea, and fatigue. Preventing altitude sickness requires not only knowledge but also conscious action and judgment during the climb.
For example, it is recommended to acclimatize for about an hour at a mountain hut before sleeping, as sleeping immediately can shallow breathing and increase the risk of altitude sickness.
It is also important not to rely too heavily on canned oxygen but to practice deep breathing to aid acclimatization.

The “Three Golden Rules” All Climbers Must Follow

To prevent accidents involving international climbers, it is essential to understand both Japanese climbing culture and the risks of climbing Mount Fuji as a high-altitude peak.
All climbers should follow these three golden rules:

Avoid “Bullet Climbing.”

Bullet climbing – attempting to reach the summit in a single push without staying overnight at a mountain hut – dramatically increases the risk of accidents from altitude sickness and exhaustion.
It does not allow for enough sleep or time for acclimatization.
The safe climbing principle is to stay overnight at a mountain hut, allowing your body to acclimatize to the altitude as you ascend slowly.

Prepare with the Right Gear.

The weather on Mount Fuji is unpredictable, and low-altitude standards do not apply.
You need a waterproof and windproof rain suit, a warm fleece, and a moisture-wicking base layer for proper layering and temperature regulation.
You must also be prepared with essential gear, including a headlamp for night hiking, a map to prevent getting lost, small change for paid toilets, and food and water with electrolytes to prevent heatstroke.

Have the Courage to Turn Back.

Prioritize “returning home safely” over reaching the summit.
If you feel any physical anomalies, such as severe headaches or nausea, it could be a sign of altitude sickness.
In such cases, the most critical decision is to descend immediately without pushing yourself.
The mountain will always be there. Having the courage to try again another time is the first step toward a safe climb.

Conclusion: Enjoying Your Conversation with Mount Fuji

Mount Fuji speaks to us through its epic history, rich culture, and the vitality of an active volcano.
Just as its past eruptions created its present landscape and ancient beliefs are still alive in modern culture, Mount Fuji is a constantly changing entity.
To truly enjoy your conversation with this mountain, meticulous preparation and respect for nature are essential.

We hope the historical background and safety information provided in this article deepen your understanding of Mount Fuji and lead to a more fulfilling experience.
With thorough preparation and a safety-first mindset, face the awesome aspects of Mount Fuji and savor the deep sense of accomplishment that comes from its summit.