In the demonstration above, recorded in 2010 but only recently posted on YouTube, a safety-indifferent soul places his foot on the leading edge of a lava flow from the island’s Kilauea volcano. Not surprisingly, his shoe briefly catches fire.
Darcy Bevens, education specialist at the University of Hawaii’s Center for the Study of Active Volcanoes, told The Huffington Post the boot ignites because the molten lava is about 2,000 degrees fahrenheit. It does not stay lit because the shoe’s material does not burn efficiently, “which is why you build a campfire with wood and not boots,” she added.
The boot is quickly removed from the lava, and the indentation left behind slowly disappears, returning that portion of the lava to its original bulbous shape and showing the viscosity of the substance. “The lava begins to form a solid outer ‘skin’ where it contacts the relatively cold air and ground,” Bevens said of this property, “but the lava skin is still flexible for awhile, until it cools further and becomes a solid crust of glassy rock.”