Japan, the Volcanic Archipelago: A Grand Story of Awe and Blessings

The Stage of “Life” Woven by Fire and Water

The Japanese archipelago is a volcanic country situated on the Pacific Ring of Fire, one of the world’s most active volcanic belts.
This geological characteristic not only shaped Japan’s landscape but also spun a narrative deeply rooted in the spiritual world, history, culture, and daily lives of its people.
The presence of volcanoes, embodying the dichotomy of fire and water, destruction and creation, is more than a mere geographical feature for the Japanese people.
It’s the very stage of “life” itself, a constant companion that has, from ancient times to the present day, simultaneously been a source of dreaded disasters and a blessing that brings abundance and healing.

This article will explore this magnificent history of coexistence with volcanoes from multiple perspectives: faith, science, history, and economics.
We will examine in detail how the Japanese people have confronted volcanoes, from the deities of volcanoes recounted in mythology to the modern scientific technology supporting disaster prevention, the lessons learned from historical eruptions that caused immense damage, and the utilization of volcanic blessings like hot springs and geothermal power generation.

Volcanoes as Sacred Lands Where Deities Reside

The Origins of Animism and Volcanic Faith: How Awe Created Belief

Faith in volcanoes on the Japanese archipelago finds its roots in the ancient animistic belief system that deified the forces of nature.
Volcanic activity – the upheaval of the earth, the thunderous roars, and the flames and smoke scorching the sky – was seen as a manifestation of the gods, a power humans could not possibly control.
A prime example of this is Mount Mihara on Izu Oshima (an island off the coast of the Izu Peninsula), which has long been revered and feared as “Goshinka-sama” (Lord Sacred Fire) or “Mihara-daimyojin.”

At Mount Aso, in particular, the crater itself is considered a sacred object where a deity resides, making it the central object of worship for Aso Shrine, which is said to have been founded in 282 BCE.
Aso Shrine consists of a lower shrine on the caldera floor and an upper shrine (Aso Sanjo Shrine) located just over a hundred meters from the crater.
This unique structure, where both shrines venerate the crater as a sacred object, is a testament to the deep-seated belief that the volcano is not just a mountain but the “living earth” itself, harboring life.
This belief system is thought to have been a way of holistically understanding the contradictory phenomena of abundant blessings and destructive disasters brought by volcanic activity.
The deities of Aso Shrine were believed to have both a benevolent and a malevolent side, a clear reflection of the dual nature of volcanoes.

A History of Coexistence Etched in Mythology and Rituals

Mount Aso has a grand myth that tells of its formation.
Takeiwatatsu-no-mikoto, the main deity of Aso Shrine, was a grandson of Emperor Jimmu.
He was said to have been ordered to cultivate the land of Aso.
The legend of “Tateno-Keppari” tells how Takeiwatatsu-no-mikoto broke a part of the somma (the outer rim of the caldera) to drain the huge lake that was Aso Valley, creating the vast plains that exist today.
This suggests that the magnificent plains within the caldera were brought about by the power of a god.
I’ve visited the area many times, and the somma of Aso is so magnificent and beautiful that one can’t help but feel a divine presence.

This faith was not limited to mere rituals; it functioned as a concrete code of conduct deeply connected to people’s lives.
The rituals and festivals held at Aso Shrine have two crucial roles: to prevent eruptions and to ensure a bountiful harvest.
For example, priests of Aso Shrine have, since ancient times, meticulously monitored the water level at the bottom of the crater and reported any changes to the imperial court.
If a change was interpreted as a bad omen, the court would order fervent prayers at shrines nationwide to prevent a disaster for the entire country.
This fact shows that the signs of volcanic activity were not only seen as a matter of survival for one region but also as a serious issue affecting the security of the entire nation.
The idea that appeasing a god’s anger would lead to national stability functioned as a governing principle in a society coexisting with volcanoes.

Furthermore, rituals to calm eruptions are still carried on today.
The chief priest of Saiganden-ji Temple, located at the foot of Mount Aso, chants sutras to pray for the mountain’s tranquility, and the priests of Aso Shrine still perform the “Crater Calming Ritual” every June, where they throw offerings into the crater.

Pilgrimage and Shugendo: Deepening Faith at Mount Fuji and Mount Ontake

Faith in volcanoes deepened from collective rituals into the personal spiritual world of individuals who sought to confront themselves through rigorous training. When volcanic activity settled in the 11th century, Mount Fuji became a training ground for Shugenja (ascetics). By the 15th century, ordinary pilgrims also began “tohai” (worshipper’s ascent). This ascent was a spiritual journey to understand one’s limits, likened to the arduous journey of life itself.

That’s right, climbing mountains in Japan was not just a leisure activity; it was a form of sacred ritual.

Mount Ontake faith, established with Shugendo as its foundation, saw ordinary people forming “Ontake-ko” groups to climb the mountain. In the Shugendo of Mount Ontake, there is a belief that human souls are born from the mountain and return to it. Over 20,000 stone monuments called “reijin-hi” (spirit god monuments) have been erected on the mountain to appease the souls of the deceased. This shows that faith in volcanoes diversified its forms over time, evolving from collective rituals to individual spiritual quests and even influencing the formation of views on life and death.

The Reality of Active Volcanoes: Their Number and Warnings

The Number of “Active Volcanoes” in Japan

While volcanic faith has deep roots, modern society uses scientific knowledge to objectively understand volcanic activity and apply it to disaster prevention. The Japan Meteorological Agency (JMA) defines an “active volcano” as “a volcano that has erupted within approximately the last 10,000 years or is currently showing active fumarolic activity.” This definition was changed from the previous “volcano that has erupted within approximately the last 2,000 years” to reflect the improvement in modern disaster prevention awareness. By including a broader range of volcanic activity, it allows for a scientific assessment of potential risks, as records of past large-scale eruptions have become geologically apparent.

Based on this definition, there are currently 111 active volcanoes in Japan. This fact shows that the Japanese archipelago, where about 70% of the land is mountainous, is always on the verge of volcanic threats. It could be said that Japan is a country with a very risky landmass.

Modern Volcanic Monitoring and Eruption Alert Levels

The ancient approach of “gauging the gods’ mood” has been replaced by the scientific indicator of “Eruption Alert Levels” in modern times. However, the underlying purpose of “protecting people’s safety” remains the same.
The JMA classifies dangerous zones and appropriate disaster response measures into five levels based on the status of volcanic activity, which are announced along with an “Eruption Warning.”
This is a crucial piece of social infrastructure that uses scientific technology to visualize volcanic activity and enable residents to take specific evacuation actions.

The eruption alert level system is used for 49 of the 50 volcanoes under constant observation (as of August 2025).
The following table shows the major volcanoes currently under alert.

Major Active Volcanoes and Eruption Alert Levels in Japan (as of 2025)

For volcanoes like Mount Aso and Sakurajima, which have historically erupted repeatedly, volcanic activity is constantly monitored, and levels are changed promptly.
This system symbolizes modern wisdom, which has transformed volcanoes from objects of awe into objects that can be understood and whose risks can be managed by science.

Lessons from History That Shook the Earth

Kikai Caldera: The World’s Largest Eruption in the Jomon Period

The volcanic archipelago of Japan is etched with a history of unimaginable, super-volcanic eruptions.
Approximately 7,300 years ago, the Kikai Caldera, located about 100km south of Kagoshima City on the seabed, experienced the world’s largest caldera eruption in the last 10,000 years.
This eruption occurred during the Jomon period, when there were no written records, and its specific impact has been revealed only through geological stratum surveys.

The pyroclastic flow generated by the eruption crossed the sea and struck the Satsuma and Osumi Peninsulas in southern Kagoshima Prefecture, annihilating the lives of Jomon people over a wide area.
According to research reports, it took a long period of 600 to 900 years for the laurel forests to recover after the eruption.
Furthermore, volcanic ash reached the stratosphere and was carried by the westerlies, with centimeter-thick deposits found as far away as the southern Tohoku region.
This fact indicates that the eruption was a global event that affected the entire Japanese archipelago.
The Kikai Caldera eruption is not just a record of a past disaster but a crucial case study that concretely suggests the potential risk of a super-volcanic eruption that the Japanese archipelago faces.
It’s even been pointed out that magma may still be accumulating beneath the caldera.

This is a very frightening story.

The Taisho Eruption of Sakurajima: Modern Japan’s Greatest Volcanic Disaster

If the Kikai Caldera was an ancient threat, the greatest volcanic disaster modern Japan faced was the Taisho Eruption of Sakurajima in 1914. At the time, Sakurajima was considered a dormant volcano, and people were barely aware of the danger of an eruption.
However, various precursor phenomena occurred before the eruption, such as a drop in well water levels and felt earthquakes, which prompted many islanders to start evacuating on their own.
This voluntary evacuation was successful in limiting human casualties on the island.
However, the Kagoshima Meteorological Observatory at the time had announced “no danger of eruption,” and the gap between the experts’ judgment and the residents’ experience served as a lesson about the difficulty of information transmission and evacuation decisions during a disaster.

The eruption, which began on January 12, 1914, generated lava flows.
The lava that flowed from the western flank buried Karasujima, an island off the coast, and the lava from the eastern flank filled the Seto Strait, connecting Sakurajima to the Osumi Peninsula.
This eruption is not just a record of a natural disaster but also a record of a social disaster that highlighted the importance of community knowledge and mutual aid organizations.
After the eruption, roads and rivers were quickly restored, but large-scale restoration work called “tenchi-gaeshi” (turning the earth over) was necessary for the farmlands covered in thick layers of ash.
Residents who lost their homes were forced to relocate to the Osumi Peninsula, Miyazaki Prefecture, and even as far as the Korean Peninsula with support from the government and prefecture.

Mount Aso: Records of Eruptions Etched in History and Modern Times

Mount Aso is characterized by its vast caldera, formed by four large-scale eruptions, including a gigantic eruption approximately 90,000 years ago.
The pyroclastic flow from the eruption 90,000 years ago was so massive that its deposits were found in Yamaguchi Prefecture, separated by the sea.

Since the Showa era, Mount Aso has erupted every few years to a decade, affecting people and agriculture.
In 1958, an explosive eruption near the crater resulted in 12 deaths and 28 injuries, and in 1979, another eruption with volcanic bombs and pyroclastic surges killed 3 people and injured 11.
These records show that not only large-scale eruptions but also small-scale ones and volcanic gas are a constant threat to people’s lives.
The people of Mount Aso have established a lifestyle that assumes the possibility of damage from eruptions, learning from past disasters.
This demonstrates an attitude of accepting volcanoes not as a “silent threat” but as a “constantly active force of nature” and responding accordingly.

The following table summarizes the records of major large-scale volcanic disasters in Japan.

Records of Major Large-Scale Volcanic Disasters in Japan

Volcanoes as Blessings: The Land That Brings Abundance and Healing

The Onsen Culture Fostered by Volcanoes: From Healing Spas to Tourist Resources

While volcanic activity brings destruction, it has also bestowed many blessings essential to our lives.
The most prominent example is “onsen” (hot springs).
The heat from the magma chamber beneath the volcano warms up groundwater, which then erupts to the surface as high-temperature steam or hot spring water.
Volcanic gases and underground minerals dissolve into the water, creating hot springs with diverse water qualities and benefits.
This gave rise to famous hot springs that represent Japan, such as Kusatsu Onsen and the Beppu Onsen-kyo.

In Japan, a culture of “toji” (therapeutic bathing) has long been practiced, where people stay at hot springs for extended periods to cure illnesses and injuries.
Before the development of modern medicine, hot springs were an important treatment method.
Spas were equipped with self-catering facilities and were valued as places for people to heal their bodies and minds.
Even today, hot springs have gone beyond being a mere treatment method and have become deeply rooted in Japanese culture as a crucial resource for healing and tourism.

Geothermal Power: A Clean Energy That Opens Up the Future

Another blessing from the volcanic heat source, alongside hot springs, is geothermal power.
Geothermal power is a form of clean energy that uses high-temperature steam or hot water heated by a volcano to turn a turbine and generate electricity.
Japan, with its numerous volcanoes, is said to have the third-largest geothermal resource potential in the world.

Currently, Japan’s geothermal power plants are concentrated in regions with active volcanic activity, such as Kyushu (Oita, Kagoshima, Kumamoto, etc.) and Tohoku (Iwate, Akita, etc.).
There are concerns that geothermal development could affect the volume and quality of hot springs, and there are also environmental concerns such as landscape destruction and air pollution from hydrogen sulfide emissions.
To address these issues, Kirishima City in Kagoshima Prefecture has created ordinances and guidelines to protect and appropriately use hot spring resources, aiming for the sustainable coexistence of geothermal power generation and tourist areas.
Furthermore, there are examples like the Waita Onsen-kyo in Kumamoto Prefecture, where local residents take the lead in operating a geothermal power plant and contributing to regional revitalization.

List of Major Geothermal Power Plants in Japan

Volcanic Ash Soil That Fosters Rich Crops

Volcanic activity also brings great blessings to agriculture.
The “volcanic ash soil” that forms over a long period from the accumulation of ejected clastic materials (rock fragments, ash, pumice, etc.) is a very important type of soil for agriculture.

Volcanic ash soil has a well-developed soil structure, which allows for good water and air permeability and excellent water retention capacity.
It’s also light with many pores, making it easy to till and suitable for field cultivation.
On the other hand, it also has chemical challenges, especially its property of strongly adsorbing phosphoric acid.
Although phosphoric acid is a nutrient essential for plant growth, when it’s adsorbed by the soil, it becomes difficult for plants to use.
Therefore, it was once considered unsuitable for crop production.

However, Japanese agricultural technology has overcome this challenge through the application of fertilizers and soil improvement.
The fact that regions with volcanic ash soil, such as the field cultivation areas in Hokkaido and southern Kyushu, have high productivity on par with the rice paddies of Asia and the prairies of America is a testament to the wisdom and effort of the Japanese people, who have maximized the natural blessings and overcome their challenges.
Today, these regions are a crucial foundation for Japan’s food production.

Characteristics of Volcanic Ash Soil and Its Impact on Agriculture

Conclusion: Toward a Future of Living with Volcanoes

Volcanoes on the Japanese archipelago have been deeply involved in our lives, from ancient times to the present.
They have been objects of awe where gods reside, destroyers that reshape the land, and at the same time, sources of blessings that bring abundance and healing.

Ancient people saw volcanic activity as the will of the gods and sought to appease their anger through prayers and rituals.
This wisdom and faith have transformed into a modern scientific system of “Eruption Alert Levels,” but the universal goal of protecting people’s safety remains unchanged.
The lessons from history, such as the Kikai Caldera and the Taisho Eruption of Sakurajima, are an indispensable foundation for shaping modern disaster prevention awareness.

Volcanoes are also the narrators of an endless story that continues to shape the identity and future of the people living on the Japanese archipelago.
The Japanese way of life, which has deeply embraced both awe and blessings, will continue.
What is required of us in the modern era is to learn from the past, strengthen scientific monitoring systems, and sustainably use the blessings of volcanoes while being mindful of the environment.

References

• Aso City: Mount Aso and Volcanic Worship
• Aso volcano crater restrictions information: The formation of Aso volcano
• National Archives of Japan: Sakurajima eruption
• JAMSTEC Base: The past and present of the gigantic undersea volcano “Kikai Caldera”
• government public relations: Volcanoes with a history of eruptions and volcanoes that may erupt in the future

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