Global Volcanism Program | Image GVP-04341
Two weeks after the November 13, 1985 eruption, steam rises from Las Arenas, the summit crater of Nevado del Ruiz. This view from the NNW shows pyroclastic-surge and pyroclastic-flow deposits mantling the summit icecap. Radial grooves descending the upper glacier surface were scoured by pyroclastic surges, which reached 5.5 km NW and NE of the summit. Melting of the summit icecap led to the formation of devastating lahars that traveled as far as 100 km from the volcano and caused 23,000 fatalities.
Photo by Norm Banks, 1985 (U.S. Geological Survey).