While volcanic activity can create a blue glow, it is not molten rock. This phenomenon involves a unique chemical reaction, distinct from incandescent lava flow. The blue color arises from specific gases that ignite upon contact with air, producing a display that often appears to flow like molten rock.
The Blue Phenomenon Explained
The blue light during volcanic events originates not from lava, but from the combustion of highly sulfuric gases. These gases, superheated and under intense pressure, emerge from cracks within the volcano. Upon reaching the open air, they spontaneously ignite. This ignition creates electric-blue flames that can reach heights of up to five meters, illuminating the night sky.
Conditions for this combustion include gas temperatures exceeding 360°C, or up to 600°C. As these burning gases move, some sulfur condenses into a liquid state while still aflame. This burning liquid sulfur can then flow down the volcano’s slopes, creating the illusion of blue lava rivers. This spectacle is primarily visible after sunset, as daylight obscures the blue flames.
The Kawah Ijen Volcano
The Kawah Ijen volcano complex in Indonesia is known for its consistent display of this blue fire phenomenon. Its geological characteristics create the ideal environment for sulfuric combustion. The volcano emits unusually high concentrations of sulfur-rich gases from its active vents.
Within the caldera of Kawah Ijen lies the world’s largest highly acidic crater lake. This turquoise-colored lake has an extremely low pH, with measurements as low as 0.13 to 0.5, similar to battery acid. The combination of abundant sulfur deposits and the intense heat from underground volcanic activity ensures a continuous supply of the gases that fuel the blue flames.
Clarifying “Blue Lava”
Distinguishing between the blue flames and molten lava is key. Traditional lava, molten rock, typically glows in shades of red, orange, or sometimes black, depending on its temperature and composition. The blue light at Kawah Ijen is a surface phenomenon from burning volcanic gases, not incandescent molten rock.
True lava underneath the blue flames, if visible, would be reddish. The term “blue lava” is a misnomer, describing the visual effect of burning sulfur that appears to flow like molten rock. This distinction clarifies the unique chemical process, not a change in lava’s fundamental nature.