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In the eastern end of Indonesia’s island of Java, the Kawah Ijen volcano (which comprises the Ijen crater and the crater lake) rises 9,183 feet into the sky. The peak is part of the Ijen stratovolcano complex, and all around noxious gases billow up from the harsh terrain. Throughout the past few millennia, enormous eruptions have produced a sprawling landscape of craters that stretches on for more than 45 miles. And that’s not all. Without interruption, the volcano spews out tons of sulfur to the surface from cracks in the rock (fumaroles)— and the gas is 1,100°F. The sulfur reacts with oxygen in the air and burns. The portion of sulfur fumes that condenses surges down the mountainside in the form of a steaming luminous blue river. This burning river of liquid sulfur eventually flows right into the crater lake of Kawah Ijen. This 2,950-foot-long, 1,970-foot-wide, and 656-foot-deep basin is recognized by experts for containing the largest lake of acid in the world. The ph value of the bubbling lake is 0.2— which is even more acidic than battery acid. In order to protect surrounding land from this toxic mix, in 1921 engineers constructed a huge lock on the rim of the crater that prevents uncontrolled outflow of the seething sulfurous solution. Special feature: The lock was made of blocks of pure sulfur, as no other material could withstand the corrosive fluid. Nowadays workers collect sulfur from Kawah Ijen: Volcanic gases are channeled through a series of ceramic pipes, allowing the sulfur to condense. When the runoff cools it is broken into pieces and carried away.
CAN A RIVER SPIT OUT FIRE?
Not only does a spectacular burning river of sulfur flow from Kawah Ijen, the eruption is also accompanied by a fireworks display. And it’s quite unpredictable: Without warning, 16-foot-high pillars of flames can shoot out of the blue river with explosive force.
WHAT MAKES THE LAVA BLUE?
The discharged sulfur is so hot (up to 1,100°F) that it reacts with the oxygen in the air and in the process is ignited. The result is that the sulfur begins to burn with its characteristic blue flame.
HOW DOES A VOLCANO SIMULATE LAVA?
The blue river does not actually consist of lava in the strict sense— i.e., molten rock. Instead, sulfur fumes that have condensed into liquid sulfur flow down the mountain above Kawah Ijen’s crater lake.