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Photo of rivers of blue flames from the Kawah Ijen crater on Java Island in Indonesia.

Sulfur combusts on contact with air to create stunning blue lava-like rivers of light in the Kawah Ijen crater on the island of Java.

Photograph by Olivier Grunewald

A locator map showing the island off Japan with a volcano that spews blue lava.

NG Staff

Brian Clark Howard

National Geographic

Published January 30, 2014

For several years Paris-based photographer Olivier Grunewald has been documenting the Kawah Ijen volcano in Indonesia, where dazzling, electric-blue fire can often be seen streaming down the mountain at night.

"This blue glow—unusual for a volcano—isn't, of course, lava, as unfortunately can be read on many websites," Grunewald told National Geographic in an email about Kawah Ijen, a volcano on the island of Java.

The glow is actually the light from the combustion of sulfuric gases, Grunewald explained.

Those gases emerge from cracks in the volcano at high pressure and temperature—up to 1,112°F (600°C). When they come in contact with the air, they ignite, sending flames up to 16 feet (5 meters) high.

Some of the gases condense into liquid sulfur, "which continues to burn as it flows down the slopes," said Grunewald, "giving the feeling of lava flowing."

Cynthia Werner, a research geologist with the U.S. Geological Survey (USGS) at the Alaska Volcano Observatory, told National Geographic that Grunewald's photos show an unusual phenomenon.

"I've never seen this much sulfur flowing at a volcano," she said.

Werner noted that forest fires in Yellowstone National Park have caused similar "rivers," as heat from the blazes melted the sulfur around hydrothermal vents.

"When you go to Yellowstone, you can see their traces as black lines," she said.

According to Werner, it's relatively common to find molten sulfur around volcanic fumaroles (hot vents). The mineral has a relatively low melting point of 239°F (115°C), and the temperature at the hot vents often exceeds that.

Blue volcanic fire was described in antiquity in Italy on the south slope of Mount Vesuvius and on the island of Vulcano, Grunewald said.

"Blue flames may also be observed at the base of the plume of erupting volcanoes, when ash explosions occur," he added.

Grunewald did not use any filters to capture his images of the blue fire. The burning happens day and night, but it's visible only in darkness.

Kawah Ijen volcano is the subject of a new documentary released earlier this month that was produced by Grunewald and Régis Etienne, the president of Geneva's Society of Volcanology.

Photo of Kawah Ijen Crater Lake on Java Island.
Photograph by Olivier Grunewald
Kawah Ijen Crater Lake is green because of the hydrochloric acid in the water.

Kawah Ijen Crater Lake, at the top of the volcano, is the world's largest such body of water filled with hydrochloric acid. In fact, it's the acid that makes the water green.

Werner explained how the lake became so acidic: The volcano emitted hydrogen chloride gas, which reacted with the water and formed a highly condensed hydrochloric acid with a pH of almost 0.

The lake has a volume of 1.3 billion cubic feet (36 million cubic meters), or about 1/320 of the volume of Oregon's Crater Lake.

Photo of blue flames coming from the Kawah Ijen crater on the island of Java in Indonesia.
Photograph by Olivier Grunewald
In the Kawah Ijen crater, sulfuric gases escaping from cracks ignite as they come in contact with the air.

As the burning gases cool, they deposit sulfur around the lake.

To speed up the formation of the mineral, a mining company installed ceramic pipes on an active vent near the edge of the lake, said John Pallister, a USGS geologist who has studied the volcano.

The pipes route the sulfur gases down the vent's sloping mound. When the gases cool, they condense into liquid sulfur, which then flows or drips from the pipes and solidifies into hard sulfur mats.

After the solid sulfur cools, the miners break it up and haul it off the mountain on their backs.

"I have also seen the miners spraying water from a small pump onto the pipes to promote cooling and condensation," said Pallister via email. "Sulfur stalactites sometimes form from the liquid sulfur dripping from the pipes. These are collected and sold to tourists."

Pallister added, "I have been told that the miners sometimes ignite the sulfur and/or sulfur gases to produce the blue flames that are so prominent in nighttime photographs."

Miners have been extracting sulfur here for more than 40 years. At times they work at night under the eerie blue light to escape the heat of the sun, and to earn extra income, Grunewald said.

The miners sell the sulfur for about 600 Indonesian rupiah per kilo (less than 25 U.S. cents per pound), said Grunewald. They can carry loads of 176 to 220 pounds (80 to 100 kilos) once a day—or twice if they work into the night.

Photo of a river of sulphur near the acid lake of the Kawah Ijen volcano in Indonesia.
Photograph by Olivier Grunewald
A river of sulfur flows near Kawah Ijen's acid lake.

When Grunewald photographs Kawah Ijen, he wears a gas mask as protection against toxic gases, including sulfur dioxide. "It is impossible to stay a long time close to a dense acid gas without a mask," he said.

Pallister described the miners' daily routine as "tough duty." He has seen many of them using only wet cloths as gas masks.

Some of the miners do have gas masks that visitors have given them, said Grunewald, but they "have no money and no opportunity to change the filters."

"I feel bad for these miners," Werner said. When she and her colleagues work in Indonesia, "we usually bring gas masks and leave them there with the people we work with, because sometimes they don't know that what they are breathing is harmful."

Photo of electric blue flames at the hydrothermal site of Dallol in Ethiopia.
Photograph by Olivier Grunewald
In Ethiopia's Danakil Depression, the sulfur dust in the soil of a hydrothermal vent ignites to form blue flames.

Grunewald has also documented the blue glow on the Dallol volcano in the Danakil Depression, in the Afar region of Ethiopia near the borders of Eritrea and Djibouti.

The heat of magma sometimes ignites the sulfur dust in the soil, forming flames of electric blue.

"It is very rare to see that," said Grunewald. "The powder of sulfur could burn for a few days."

The depression is geologically active, with hydrothermal vents and sulfur springs, some of which are tourist attractions.

The Afar region is famous for having the world's highest average temperature of 93°F (34°C), thanks in part to the volcanic activity.

81 comments
King Richard
King Richard

I always thought the lake was filled with Sulfuric Acid. Am I wrong or is it really Hydrochloric Acid?

Bonnie Jameson
Bonnie Jameson

This is a little old, but I just found this. There are some amazing photos in here.

Jeremy Daker
Jeremy Daker

I know alien terraforming when I see...  SCIENCE they say.. bah

Subrata Sarkar
Subrata Sarkar

There are so many wonders of nature!We are grateful to those who are exploring deeper to reveal them.

Ronice Awudu
Ronice Awudu

This was the reason why I joined, just to grab this picture - beautiful!

mbanx trivisia
mbanx trivisia

poor me ..... I live in a nearby town only 70 miles from the site but I have never been there even for once . I am so very jealous to you guys

thanks for bring me those amazing pictures

mbanx trivisia
mbanx trivisia

poor me .... I live in a town only 70 miles from the site but never come to this place even for once , I am so very jealous to you guys

Anna Jean
Anna Jean

truly amazing and to the person who brought us these wonderful shots... thank you :)

LuVitas Young
LuVitas Young

不是修圖的!!電子藍的噴焰~!看起來更夢幻了!!!

rut brea
rut brea

These are all beautiful photographs. How blessed are those who can travel around the world and create their own art in Photography. I love to paint and am always drawing around my neighborhood, and the park. I have never been able to travel the world, but sometimes take a photograph and create another painting of my own. Thank you National Geographic for your mail. I wish I could donate for the great job you are doing, but am unable at present. Again thank you for all these beautiful work!

Russell Coleman
Russell Coleman

These examples are what blow the environmentalists BS right out of the water. Lakes of naturally occurring hydrochloric acid. Rivers of sulfur and natural plumes of sulfur dioxide that are trillions of times more than all the output of all the diesel trucks on the road. 450 million gallons of oil that leaks into the floors of all the oceans naturally. These are all natural phenomenon and they are only a fraction of all the things naturally occurring that environmentalists would lose there minds over if  a company was to store in open containers. The hypocrisy and lack of education is destroying the lives of good people and yet the green crusaders march on convinced of there green cause and striking down all of those who dare think for themselves or point out the simple obvious truth's.

Aaron Medlock
Aaron Medlock

happy belated birthday to my cousins on 1/31 

John Boardman
John Boardman

Incredible nature at work and what an opportunity for photo work, brilliant piece of work here.

Karisa Keahey
Karisa Keahey

I didn't know that there was blue lava flow. This is an amazing phenomenon.

S. Sirgany
S. Sirgany

Fascinating! We live on such an incredible planet.

Alejandro Roman
Alejandro Roman

It's like the color of our blood before it hits oxygen

John Clutter
John Clutter

Convergence of physical forces in dynamic expression!

King Hu
King Hu

Like the flame comes from the devils.

Ned G.
Ned G.

This picture is amazing!

Maggie Stevenson
Maggie Stevenson

Stunning photos. Great, informative article - sounds like a rough job for those miners.


-Maggie

maggiefinejewelry.com

mark tresise
mark tresise

@Russell Coleman

I am guessing that if I point out the irony of your comments particularly, 'BS', 'hypocrisy' and certainly 'lack of education' it would be lost upon you?

mark tresise
mark tresise

@Russell Coleman

I am guessing that if I point out the irony of your comments particularly, 'BS', 'hypocrisy' and certainly 'lack of education' it would be lost upon you?

Chris Mason
Chris Mason

@Y Q  Either I’m completely misunderstanding what you are trying to say (in which case I am sorry), or you are way off the mark with this statement. It clearly states in the above article that it is Sulphur (in liquid form) that is combusting on contact with the atmosphere which is producing the blue colour.

Your initial statement “When the carbon condenses with the oxygen and overheats making hydrogen” is an absolute gem.

Grey 155
Grey 155

@Alejandro Roman  That is actually a myth. Our blood is red when it is in our , but it turns a brighter red when it hits oxygen.

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