Tuesday, May 6, 2014
Blue flame from sulfur burning at the Kawah Ijen volcano in Indonesia.
The electric-blue fire is often mistakenly called "blue lava", but it is in fact sulfur fumes igniting in the hot air above the lava.
Sometimes the gas cools some but not much, and condenses into liquid sulfur. It continues to burn as it flows down the side of the mountain, leading those who don't know what's happening to conclude that it is blue lava.
This blue sulfuric fire has been seen lots of times, particularly in Yellowstone National Park and at Vesuvius. But the Kawah Ijen volcano contains extremely high levels of sulfur, so the blue fire is almost constantly visible there.