Overview of Asian Volcanoes: From Fuji to Krakatoa

Eruption of Merapi in Indonesia — *Asia is home to more than half of the planet's active volcanoes, mainly in the Pacific Ring of Fire (Japan, Indonesia, Philippines, Kamchatka). Image source: astronoo.com (new window)*

Historical Volcanic Eruptions in Asia

Krakatoa (Krakatau), 1883

The eruption of Krakatoa in Indonesia on August 26-27, 1883 is one of the most violent and famous in history. The explosion, heard as far away as Australia, destroyed the volcanic island and triggered a devastating tsunami that killed more than 36,000 people. Ash ejected into the atmosphere darkened skies worldwide, creating spectacular sunsets and global cooling for several years. This event marked the birth of modern volcanology.

Tambora, 1815

The eruption of Mount Tambora, also in Indonesia, in April 1815, is the most powerful ever recorded in human history. It caused a global "volcanic winter" in 1816, known as the "Year Without a Summer," with disastrous harvests in Europe and North America. The eruption killed more than 71,000 people, directly or indirectly, and left a 7 km wide caldera. It had a profound impact on global climate and societies.

Mount Pinatubo, 1991

The eruption of Mount Pinatubo in the Philippines on June 15, 1991 was the second-largest eruption of the 20th century. It ejected ash up to 40 km into the atmosphere, causing global temperatures to drop by nearly 0.5°C for two years. Pyroclastic flows and lahars devastated surrounding regions, killing more than 800 people and displacing thousands. This eruption also allowed for the testing and improvement of early warning systems.

Mount Unzen, 1792

The eruption of Mount Unzen in Japan in 1792 is famous for causing one of the worst volcanic disasters in the country's history. A series of explosions triggered a massive landslide that buried the city of Shimabara and caused a tsunami in Ariake Bay, killing more than 15,000 people. This event inspired literary and artistic accounts and remains a symbol of volcanic dangers in Japan.

Mount Fuji, 1707

The last major eruption of Mount Fuji in Japan occurred in December 1707. Known as the Hōei eruption, it lasted two weeks and covered Edo (modern-day Tokyo) in ash. Lava flows and ash caused significant damage to crops and infrastructure. This eruption had a deep cultural impact, influencing Japanese art and literature, and remains a reminder of the destructive power of this national symbol.

Toba, around 75,000 years ago

The eruption of the Toba supervolcano in Indonesia around 75,000 years ago is the largest known on Earth in the last 25 million years. It ejected approximately 2,800 km³ of material into the atmosphere, causing a global volcanic winter that nearly led to human extinction. Geological evidence of this eruption is still visible today, and it remains a crucial subject of study to understand the impacts of super-eruptions on climate and biodiversity.

Mount Merapi, 2010

The eruption of Mount Merapi in Indonesia in October-November 2010 was one of the most violent of the 21st century. Pyroclastic flows devastated surrounding villages, killing more than 350 people and displacing hundreds of thousands of residents. Ash disrupted air traffic in Southeast Asia and reminded the world of the constant threat posed by Indonesian volcanoes, some of the most active on the planet.

Mount Sakurajima, 1914

Mount Sakurajima in Japan is one of the world's most active volcanoes. Its major eruption in 1914 produced enormous lava flows that connected the volcanic island to the Ōsumi Peninsula. Although recent eruptions have been less destructive, Sakurajima remains under close monitoring due to its almost constant activity and proximity to the city of Kagoshima, home to more than 600,000 people.

Dynamics and Danger of Asian Volcanoes

The Pacific Ring of Fire

The Asian continent lies at the heart of the Pacific Ring of Fire, a subduction zone where oceanic plates sink beneath continental plates. This gives rise to volcanic arcs of exceptional intensity: Japan, Indonesia, the Philippines, the Kurils, and Kamchatka. Most of these volcanoes are of the gray type, explosive, with spectacular and sometimes cataclysmic eruptions.

Indonesian Island Volcanoes

Indonesia is the country with the largest number of active volcanoes (over 120). They result from the subduction of the Indo-Australian Plate under the Eurasian Plate. Among them, Merapi, Krakatoa, and Tambora are sadly famous for their deadly eruptions. These volcanoes are rich in dissolved gases and regularly produce pyroclastic flows and volcanic tsunamis.

Volcanoes of Japan

In Japan, more than a hundred volcanoes are active, including Fuji, Aso, and Sakurajima. These volcanic structures directly threaten densely populated megacities (Tokyo, Kagoshima). The combination of a high explosive hazard and high urban vulnerability makes Japan one of the countries most exposed to volcanic risk.

The Philippines and the Sunda Arc

The Philippines is home to iconic volcanoes such as Pinatubo, whose 1991 eruption was one of the most powerful of the 20th century, injecting millions of tons of sulfur into the stratosphere. Further south, the Sunda Arc (Krakatoa, Tambora) has produced some of the most destructive eruptions in human history.

Kamchatka and the Kurils

The Kamchatka Peninsula (Russian Far East) is a region of exceptional volcanic density, listed as a UNESCO World Heritage Site. Stratovolcanoes such as Klyuchevskoy and Bezymianny are in almost constant activity. Further south, the Kuril Islands also have many active volcanoes, often isolated but powerful.

Red and Gray Volcanoes of Asia

While Asia is best known for its explosive gray volcanoes, it also has effusive red volcanoes, such as some basaltic cones in the Philippines and Java. These volcanoes produce spectacular fluid lava flows, but they are generally less deadly than explosive eruptions.

Table of Main Asian Volcanoes

Main Active and Dormant Volcanoes of Asia
Volcano	Color	Location	Type	Altitude (m)	Last Eruption	Status	Comment
Merapi	Gray	Indonesia, Java	Stratovolcano	2911	2021	Active	Very active, frequent threat to Yogyakarta.
Mayon	Gray	Philippines, Luzon	Stratovolcano	2463	2023	Active	Near-perfect cone, frequent eruptions.
Sakurajima	Gray	Japan, Kyushu	Stratovolcano	1117	2023	Active	One of Japan's most active volcanoes, close to Kagoshima.
Klyuchevskoy	Gray	Russia, Kamchatka	Stratovolcano	4750	2022	Active	Highest active volcano in Eurasia, continuous activity.
Sinabung	Gray	Indonesia, Sumatra	Stratovolcano	2460	2021	Active	Awakened in 2010 after 400 years of dormancy.
Anak Krakatau	Gray	Indonesia, Sunda Strait	Caldera / Stratovolcano	813	2018	Active	Major historical eruption in 1883, Anak Krakatau is growing.
Unzen	Gray	Japan, Kyushu	Volcanic Complex	1500	1995	Active	Unstable lava domes, deadly eruption in 1991.
Aso Volcano	Gray	Japan, Kyushu	Caldera	1592	2020	Active	Large caldera, fumarolic activity and occasional explosions.
Lokon-Empung	Gray	Indonesia, Sulawesi	Stratovolcano	1580	2023	Active	Double volcano, frequent activity with pyroclastic flows.
Taal	Gray	Philippines, Luzon	Caldera	311	2020	Active	Volcano in a lake, frequent explosive eruptions.
Mount Fuji	Gray	Japan, Honshu	Stratovolcano	3776	1707	Dormant	Symbol of Japan, potentially active but currently dormant.
Pinatubo	Gray	Philippines, Luzon	Stratovolcano	1486	1991	Dormant	One of the largest eruptions of the 20th century.
Mount Ararat	Gray	Turkey	Stratovolcano	5137	Non-historical	Dormant	Biblical volcano, probably extinct but monitored.
Damavand	Gray	Iran, Elburz	Stratovolcano	5610	~5350 BC	Dormant	Highest peak in the Middle East, fumarolic activity.
Baekdu	Gray	North Korea / China	Caldera	2744	1903	Dormant	Major volcanic caldera, historical eruption in 946 AD.
Kunlun	Gray	China, Tibet	Stratovolcano	6500	Holocene	Dormant	Rarely active, high summit in the Tibetan mountains.
Tengger (Bromo)	Gray	Indonesia, Java	Caldera / Stratovolcano	2329	2023	Active	Famous for its tourist landscapes, moderate activity.
Gamalama	Gray	Indonesia, Halmahera	Stratovolcano	1715	2023	Active	Very active, threat to the city of Ternate.
Semeru	Gray	Indonesia, Java	Stratovolcano	3676	2023	Active	Highest volcano in Java, frequent eruptions.
Rinjani	Gray	Indonesia, Lombok	Stratovolcano / Caldera	3726	2016	Active	Large caldera with a crater lake, regular volcanic activity.

Red and Gray Volcanoes: Two Eruptive Dynamics

So-called red volcanoes correspond to effusive volcanoes, characterized by fluid lava flows and relatively low gas content. Their magma is basaltic, with low viscosity, allowing gases to escape easily. In Asia, they are found in certain areas of Indonesia and the Philippines.

In contrast, gray volcanoes correspond to explosive volcanoes, where the lava is more viscous, rich in silica and dissolved gases. The buildup of pressure leads to violent eruptions, with ash plumes, pyroclastic flows, and glowing avalanches. Most Asian stratovolcanoes (Merapi, Pinatubo, Sakurajima) are of this type.

Comparison Between Red and Gray Volcanoes
Characteristic	Red Volcanoes	Gray Volcanoes
Magma Type	Basaltic, low in silica (<52% SiO₂)	Andesitic to rhyolitic, rich in silica (>55% SiO₂)
Viscosity	Low \(\eta \sim 10^{1-3}\, \text{Pa·s}\)	High \(\eta \sim 10^{5-9}\, \text{Pa·s}\)
Eruptive Style	Effusive: fluid lava flows	Explosive: ash plumes, pyroclastic flows
Visible Manifestations	Incandescent red lava, gentle cones	Gray ash layers, steep stratovolcanoes
Main Risks	Slow but destructive lava flows	Pyroclastic flows, sudden explosions, ashfall
Asian Examples	Small basaltic cones of Indonesia	Merapi (Java), Pinatubo (Philippines), Sakurajima (Japan)