Global Volcanism Program | Image GVP-03836
A steaming blocky lava flow from El Brujo, the westernmost of the Santiaguito vents, advances down a SW-flank valley in November 1973. Santiaguito has grown during a series of several-year-long extrusive spurts separated by longer periods of slower extrusion lasting about a decade. The fifth of Santiaguito's effusive cycles took place in 1972-75. This eruptive cycle produced six lava flow units and a small lava dome. It was unusual in that extrusion took place simultaneously from two vents at the western and eastern ends of Santiaguito.
Photo by William Melson, 1973 (Smithsonian Institution).