The miners sell the sulfur for about 600 Indonesian rupiah per kilo (less than 25 U.S. 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. Miners have been extracting sulfur here for more than 40 years. 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." These are collected and sold to tourists." "Sulfur stalactites sometimes form from the liquid sulfur dripping from the pipes. "I have also seen the miners spraying water from a small pump onto the pipes to promote cooling and condensation," said Pallister via email. When the gases cool, they condense into liquid sulfur, which then flows or drips from the pipes and solidifies into hard sulfur mats.Īfter the solid sulfur cools, the miners break it up and haul it off the mountain on their backs. The pipes route the sulfur gases down the vent's sloping mound. 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. Unauthorized use is prohibited.Īs the burning gases cool, they deposit sulfur around the lake. 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. The burning happens day and night, but it's visible only in darkness. Grunewald did not use any filters to capture his images of the blue fire. "Blue flames may also be observed at the base of the plume of erupting volcanoes, when ash explosions occur," he added. The mineral has a relatively low melting point of 239☏ (115☌), and the temperature at the hot vents often exceeds that.īlue volcanic fire was described in antiquity in Italy on the south slope of Mount Vesuvius and on the island of Vulcano, Grunewald said. "When you go to Yellowstone, you can see their traces as black lines," she said.Īccording to Werner, it's relatively common to find molten sulfur around volcanic fumaroles (hot vents). Werner noted that forest fires in Yellowstone National Park have caused similar "rivers," as heat from the blazes melted the sulfur around hydrothermal vents. "I've never seen this much sulfur flowing at a volcano," she said. Geological Survey (USGS) at the Alaska Volcano Observatory, told National Geographic that Grunewald's photos show an unusual phenomenon. 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."Ĭynthia Werner, a research geologist with the U.S. When they come in contact with the air, they ignite, sending flames up to 16 feet (5 meters) high. Those gases emerge from cracks in the volcano at high pressure and temperature-up to 1,112☏ (600☌). The glow is actually the light from the combustion of sulfuric gases, Grunewald explained. "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. 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.
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