Lava fountain of the Pu'u O'o cinder and spatter cone on Kilauea Volcano, Hawaii. Credit: J. D. Griggs, U.S. Geological Survey.
A lava fountain is an eruption of molten material from a fissure, vent, or active lava lakes. Lava fountains form when gas bubbles in molten rock rapidly expand as they reach the surface, forcing the lava to be erupted high into the air. Most lava fountains rise to about 10 to 100 meters (30 feet to 330 feet) in height, although they occasionally reach even greater heights.
The highest lava fountain ever recorded occurred in 1986 on the Izu-Oshima volcano in Japan. It reached a height of 1,600 meters (5,200 feet). The world's longest continuous lava fountain in historical time was erupted from the 25-kilometer long Laki Fissure in southern Iceland in 1783.
Lava fountains have also been observed beyond Earth, in the Tvashtar region of Jupiter's volcanically active moon Io. The Tvashtar fountains have been seen to reach a height of more than 1.5 kilometers and involve lava at a temperature of 1,000 K to 1,600 K.