VIDEO: Lava in Puna triggers blue flames
A blue-burning flame of methane gas was observed in the cracks on Kahukai Street during the overnight hours in Puna just before midnight on May 22, 2018.
When lava buries plants and shrubs, methane gas is produced as a byproduct of burning vegetation.
Methane gas can seep into subsurface voids and explode when heated, or, as shown in this video, can emerge from cracks in the ground several feet away from the lava.
When ignited, the methane produces a blue flame.