Incandescent lava is visible on the cooling surface of an advancing lava flow from Cerro Negro volcano in 1968. The flow front, which advanced at a rate of about 5 m/hr during the first day of the eruption. The flow originated from a horseshoe-shaped flank vent south of Cerro Negro.

Photo by William Melson, 1968 (Smithsonian Institution).

Cerro Negro