But this eyecatching spectacle isn’t totally unique to the East Java volcano. After all, similar “rivers” of blue fire occur at Yellowstone National Park, Wyoming, when forest fires mix with sulfur from vents. The result, then, is a brilliant blue burst of flame.
One of the most intriguing aspects of the blue flame phenomenon, however, is that it can only be witnessed at night. During the day, even though the fires burn just the same, they’re pretty much invisible to the naked eye.