Global Volcanism Program | Image GVP-04382
Galeras, one of the most active volcanoes of Colombia, rises west of the city of Pasto. The high point is the eastern rim of a large caldera that is breached to the west and serves to funnel most of the eruptive products of the volcano away from the city. Larger explosive eruptions during historical time have produced pyroclastic flows that overtopped the caldera rim.
Photo by John Ewert, 1989 (U.S. Geological Survey).