How Volcanoes Work

 Image Described in Caption
 The November 13, 1985 lahar from Nevado del Ruiz, Colombia -- After travelling over 70 kilometers from the summit of the Nevado del Ruiz volcano, this destructive lahar buried the village of Armero at the mouth of the River Lagunillas canyon, which was located in the center of this photograph. The lahar killed over 23,000 people, most of which were from Armero. Courtesy of J. Marso, USGS.