# Kawah Ijen (DD-600) > Kawah Ijen is the crater of the Ijen volcano in East Java, Indonesia. It holds a turquoise lake rich in sulfuric and hydrochloric acid. Its famous 'blue fire' (locally api biru) isn't lava. Photographer Olivier Grunewald, who documented it for years, told National Geographic and Smithsonian that the glow comes from burning sulfur-rich gases. These leave cracks at high pressure and temperatures up to 600 °C and ignite in air above about 360 °C, with flames up to about 5 m high. Some of the gas condenses into liquid sulfur that keeps burning as it runs downhill, which looks like flowing blue lava. The flames are faint, so they show only at night. USGS geologist John Pallister told National Geographic that miners sometimes light the sulfur themselves, which adds to the flames in night photos. Ijen is also a working sulfur mine. Ceramic pipes channel gas from a vent by the lake, and it condenses into molten sulfur that hardens yellow. Miners break off chunks and carry them out in baskets. Wikipedia, citing several reports, puts typical loads at 75 to 90 kg, carried up about 300 m to the crater rim and then about 3 km down, often twice a day. A 2024 study measured sulfur dioxide along the miners' path at 3.14 to 18.24 mg/m³, above the US EPA's 1.97 mg/m³ guideline. Miners reported eye irritation, coughing, headaches and shortness of breath. The footage shows bright blue flames and burning streams against the dark night slopes. - Department: Nature (also Locations) - First published: 2025-06-19 - Last updated: 2025-06-19 - Permalink: https://detailenjoyer.com/case/kawah-ijen/ - Author: Marcus Easterling (DetailEnjoyer), The Detail Department ## Quick facts - **DD-600-F01**: Kawah Ijen's blue glow is burning sulfur, not lava. _(Write-up · Exhibit A (Not lava))_ - **DD-600-F02**: Ijen's sulfur miners carry loads of about 75 to 90 kg. _(Write-up · Exhibit D (A working mine))_ ## Write-up Blue fire, not blue lava. Burning sulfur gas glows blue at night in East Java. 1. **Not lava**: The blue glow is burning sulfur-rich gas, not blue lava. 2. **Hot gas meets air**: Gas emerges at up to 600 °C and ignites in air, with flames up to about 5 m high. 3. **Burning rivers**: Some gas condenses into liquid sulfur that keeps burning as it flows downhill. 4. **A working mine**: Miners carry loads of about 75 to 90 kg up to the crater rim, often twice a day. 5. **Toxic air**: A 2024 study measured sulfur dioxide on the miners' path above the US EPA guideline. ## Related case files - [Danakil Depression (DD-055)](https://detailenjoyer.com/case/danakil-depression/): Dallol, in the Danakil, also has blue sulfur fire - [Fissure Flames (DD-645)](https://detailenjoyer.com/case/fissure-flames/): Another volcano case - [Ayam Cemani (DD-576)](https://detailenjoyer.com/case/ayam-cemani/): Another case from Java ## Reel vs. record - **Note**: 'Renowned for its striking blue lava': the Reel itself corrects this. The lava isn't blue; the color comes from burning sulfur gas and liquid sulfur. - **Note**: 'Combustion of sulphuric gases': more precisely, sulfur-rich volcanic gases and sulfur vapor. Sulfuric acid is in the crater lake, not what burns. - **Note**: 'Visible only at night': the flames are there by day but too faint to see in daylight. - **Note**: 'A rare geological phenomenon': Ijen is the largest known blue-flame area. Blue sulfur fire has also been reported at Dallol in Ethiopia. - **Missing**: Ijen is a working sulfur mine. Miners haul sulfur out by hand through sulfur dioxide levels a 2024 study found above the US EPA guideline. ## Video: Kawah Ijen: Blue Fire, Not Blue Lava - Duration: 27.5 s · Published: 2025-06-19 - File: https://detailenjoyer.com/assets/videos/DLFhsI_R7ll.mp4 ### Transcript DID YOU KNOW? Kawah Ijen volcano in East Java, Indonesia, is renowned for its striking blue lava, a rare geological phenomenon. This electric blue glow, visible only at night, is not true lava, but results from the combustion of sulphuric gases. These gases, released at high pressures and temperatures up to 600 °C, ignite upon contact with oxygen-rich air, producing vibrant blue flames. As the sulfur burns, some condenses into molten form, flowing down the volcano and creating the illusion of blue lava. NOW YOU KNOW! ## Questions & answers **Q: What makes Kawah Ijen's blue glow?** A: Sulfur-rich gas burns blue. _(Source: Write-up · Exhibit A (Not lava) · National Geographic: Stunning electric-blue flames erupt from volcanoes; Smithsonian Magazine: Why does this Indonesian volcano burn bright blue?)_ **Q: Up to what temperature does the gas emerge?** A: It ignites on contact with air. _(Source: Write-up · Exhibit B (Hot gas meets air) · National Geographic: Stunning electric-blue flames erupt from volcanoes; Wikipedia: Ijen)_ **Q: How high can the flames reach?** A: Per Grunewald, via National Geographic. _(Source: Write-up · Exhibit B (Hot gas meets air) · National Geographic: Stunning electric-blue flames erupt from volcanoes; Wikipedia: Ijen)_ **Q: On which island is Kawah Ijen?** A: East Java, Indonesia. _(Source: Write-up · Exhibit A (Not lava) · National Geographic: Stunning electric-blue flames erupt from volcanoes; Smithsonian Magazine: Why does this Indonesian volcano burn bright blue?)_ **Q: How heavy are typical miners' loads?** A: Carried up to the crater rim and down the mountain. _(Source: Write-up · Exhibit E (Toxic air) · Environmental health risk assessment and acute effects of SO2 exposure on traditional sulfur miners at Ijen Crater (2024, PMC))_ ## Sources - [National Geographic: Stunning electric-blue flames erupt from volcanoes](https://www.nationalgeographic.com/science/article/140130-kawah-ijen-blue-flame-volcanoes-sulfur-indonesia-pictures) - [Smithsonian Magazine: Why does this Indonesian volcano burn bright blue?](https://www.smithsonianmag.com/science-nature/why-does-indonesian-volcano-burn-bright-blue-180949576/) - [Wikipedia: Ijen](https://en.wikipedia.org/wiki/Ijen) - [Environmental health risk assessment and acute effects of SO2 exposure on traditional sulfur miners at Ijen Crater (2024, PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11533650/) ## Cite this case file Easterling, Marcus. "Kawah Ijen." The Detail Department (DetailEnjoyer), case file DD-600, last updated Jun 19, 2025. https://detailenjoyer.com/case/kawah-ijen/